Problem With Temperature

[Loe]

Hello every body.

I have a RX400H from 4 months.

It's a fantastic car.

All was working perfectly.

But...

But from few days, the hybrid system doesn't work very well.

Where I live (in Paris - France ) it started to be cold from few days. Not so cold, but let say the outside temperature is going up to 32 ° F.

Well, my Lexus stay outside during the night.

In the morning the temperature is around 46° F, and I drive it to my work during 8 miles (around 25 minutes) : the electric engine doesn't work. The batteries starts to be in the green level quickly, and as soon as I touch the pedal, the petrol engine starts. When I stop to a red light, the petrol engine doesn't stop.

Than after few hours in the garage of my company, I go to lunch and the electric engines start to work normally.

I spoke with my dealer which was very surprised. He never heard about that. Than he call someone, and told me there is a minimum required temperature for the electric engines. He spoke about 60 °. Was it Fahrenheit or Celsius ? He didn't know. FYI 60° C is equal to 140° F. (he wasn't clear, I think he didn't understand what was explained to him)

But anyway, after few minutes of driving the petrol engine is hot, and that should work.

Does any body has the same issue ?

(I don't know if it could have any links, but during summer, one or 2 times I noticed some water under the car but I did not use the air conditioning.)

Thanks in advance for your answer.

[retired00]

Hello every body.

I have a RX400H from 4 months.

It's a fantastic car.

All was working perfectly.

But...

But from few days, the hybrid system doesn't work very well.

Where I live (in Paris - France ) it started to be cold from few days. Not so cold, but let say the outside temperature is going up to 32 ° F.

Well, my Lexus stay outside during the night.

In the morning the temperature is around 46° F, and I drive it to my work during 8 miles (around 25 minutes) : the electric engine doesn't work. The batteries starts to be in the green level quickly, and as soon as I touch the pedal, the petrol engine starts. When I stop to a red light, the petrol engine doesn't stop.

Than after few hours in the garage of my company, I go to lunch and the electric engines start to work normally.

I spoke with my dealer which was very surprised. He never heard about that. Than he call someone, and told me there is a minimum required temperature for the electric engines. He spoke about 60 °. Was it Fahrenheit or Celsius ? He didn't know. FYI 60° C is equal to 140° F. (he wasn't clear, I think he didn't understand what was explained to him)

But anyway, after few minutes of driving the petrol engine is hot, and that should work.

Does any body has the same issue ?

(I don't know if it could have any links, but during summer, one or 2 times I noticed some water under the car but I did not use the air conditioning.)

Thanks in advance for your answer.

I assume you have the same catalytic converter we have in the US, and it must be maintained at a hot temperature in order to work on exhaust emissions, so it calls for the gas engine to run in order to keep the converter hot. I think that may be what you're seeing, so the colder it is and the shorter your trip, the more it would call for the gas engine. Later in the day, the outside temp will assist with the process and the converter will warm faster.

[SW03ES]

This is a downside of the hybrid system in the winter, it relies much more on the gas engine to keep the system at a normal operating temperature. You'll see economy declines in the winter.

[NeoN]

Hello every body.

I have a RX400H from 4 months.

It's a fantastic car.

All was working perfectly.

But...

But from few days, the hybrid system doesn't work very well.

Where I live (in Paris - France ) it started to be cold from few days. Not so cold, but let say the outside temperature is going up to 32 ° F.

Well, my Lexus stay outside during the night.

In the morning the temperature is around 46° F, and I drive it to my work during 8 miles (around 25 minutes) : the electric engine doesn't work. The batteries starts to be in the green level quickly, and as soon as I touch the pedal, the petrol engine starts. When I stop to a red light, the petrol engine doesn't stop.

Than after few hours in the garage of my company, I go to lunch and the electric engines start to work normally.

I spoke with my dealer which was very surprised. He never heard about that. Than he call someone, and told me there is a minimum required temperature for the electric engines. He spoke about 60 °. Was it Fahrenheit or Celsius ? He didn't know. FYI 60° C is equal to 140° F. (he wasn't clear, I think he didn't understand what was explained to him)

But anyway, after few minutes of driving the petrol engine is hot, and that should work.

Does any body has the same issue ?

(I don't know if it could have any links, but during summer, one or 2 times I noticed some water under the car but I did not use the air conditioning.)

Thanks in advance for your answer.

I have had the same issue in the winter, as I just picked up my car, but as soon as the engine is warmed up, it should NOT be running when your stopped at a light regardless of the temperature outside (32 is not too cold). Definitely speak with your lexus dealer regarding your hybrid system. My engine does run right when I start it up for a couple of mins, but once the coolant needle rises above C your engine shouldn't be running when decelerating or stopped

[itmdtr]

It seems to me that the gas engine is running to heat the water so you can get heat in the car. The electric motors don't heat the water.

[SKperformance]

Agree, it is normal as it heats the coolant and cats for emissions.

[Jim Nazium]

OK, as others have mentioned above, it is critical that if the petrol engine needs to be on, the system would like to keep and maintain the catalytic converters in the optimum temperature range in order to keep the exhaust at emmission levels required by the country you drive in.

Some little tips, to keep the engine off in winter...

1) Try to park indoors as much as possible, seeing how everything is just that much warmer.

2) Try not to drive with the Climate Control system on. If you ask for the heater core to be hot in order to blow hot air inside the car immediately, the system will obviously depend on the engine to heat the water coolant in order to generate the heat necessary by the heater core. Instead, keep it off and when you get a chance to drive at a speed where the engine is required the heat that is generated there will automatically heat the coolant. Now, if you then press on the Auto Climate Control the system will deploy "ON" and the hot coolant will be directed to the heater core. At this point, since the engine is running you can leave the system on if you wish. If you are driving in heavy traffic, or come to a complete stop then I suggest you turn off the automatic climate control system. Leave it off, and when you get back up to speed, the system will still blow hot air into the cabin due to the air that is forced through by the inertia of the vehicle being driven. Also to help the amount of air flow without the use of the fan blower, you can crack open a rear window or do what I do in the winter and tilt open the sunroof. This decreases the cabin pressure and allows for more air to enter the cabin since there is less cabin pressure due to the exit opening of the sunroof / window.

3) Invest in a block heater. It's inexpensive and if you have access to an electrical outlet it will keep your engine warm as opposed to ambient sub zero temperatures.

4) Make sure your tire temperature is set at sub zero ambient temperature to ensure you are driving at the required air pressure. Every little bit helps in keeping the ICE off.

5) Use the heat seaters instead of the Auto Climate Control. Seat heaters will not trigger the ICE to start in order to heat the engine coolant while idling or driving at non-ICE speeds where the electric motors can take over.

Cheers,

MadloR

[lexpat]

From what I understand reading this thread, the ICE will run quite a bit after starting in winter to heat up the catalytic converter and the cabin. This makes sense to me.

But I believe I have a different problem with my RX400h. I have noticed a few problems since about October 2007:

- after I started the car at low but not really cold temperatures (i.e. 30s to 40s) the regenerative braking hardly works. When I look at the power gauge at the left when I step on the brakes, it only goes about 10% or so into the blue area, pretty much no matter how hard I step on it. This percentage will increase gradually when the ICE becomes warmer, but even when the ICE is hot (after 50mls highway) it still sometimes only goes to about 50% or so. And even after this 50mls highway stretch and the batteries fully charged, the ICE kicks in right away when I step softly on the pedal to accelerate.

- I also noticed that I used to be able to drive without ICE from my parking garage door to my parking spot (about 100ft) when I return home and the engine is hot, but these days the ICE is always kicks in. Up until October I could accelerate slowly, and as long as the power gauge stayed in the center area the ICE wouldn't kick in. Nowadays it always kicks in, even when I touch the pedal very softly.

- My battery gauge always displays 6 or 7 bars. For many, many weeks I haven't seen anything else on the trip info. I only managed to run with the electric motors a little after my return from a long highway drive, and then I managed to get it to 4 bars when I accelerated very carefully. I also noticed that even though it still displayed 6bars (i.e. not green) the regenerative braking is switched off occasionally (even when I tried to brake softly on a smooth road (no bumps)). I understand that it might switch off if the battery is fully charged, but it shouldn't switch off in this case. I would also expect that the battery would then be drained a little by the electric engines to support the ICE while driving and accelerating, but when I look at the trip info it often seems to charge the battery more than it drains it.

- The mileage of the car is also pretty bad these days. If I drive in the city with fairly long stretches without braking it is probably around 20mpg or so, even if the engine is warm. I think the current reading since I picked it up from the service is 20.6mpg. I used to achieve around 26mpg before the hybrid parts started misbehaving.

I understand if these things happen, when the ICE is cold, but I can't understand why they are happening when the ICE is hot. I had told my Lexus service about this problem when I had the car in for the 20k service, but they said the car is fine and they couldn't find anything wrong with it. After reading all your posts I also tried switching the AC completely off, but that also didn't seem to make a difference.

Do you think that my battery already goes dead after 23k mls? I once had forgotten to switch off the interior light and had to jump start the car the next morning. Could it be that some engine electronics need to be reset?

I would be very happy if some of you could tell me if you experience similar behavior with your car. Any ideas of what you believe could be wrong would also be highly appreciated.

Thanks in advance for your answers.

[SOMEONE ELSE'S GOT MY NAME]

Get your self an engine block heater (EBH), and that'll be the end of it. When you try to use the cabin heater on freezing days, it causes the ICE to work more at warming YOU up, rather than working at higher effiecency. The EBH can be installed at home with simple tools that you likely have laying around in your garage. It takes a person with limited mechanicle skills, following the install directions about 3 to 4 hours at most. If you're moderately skilled, you can get it done in under 2 hours. You'll find it will increase your MPG on cold days too. That said, you need to be in a place that you can have the car pluged in for about 90 minutes to 2 hours prior to driving. They run on about 1250 watts and it'll put your temps at just over 100 degrees for instant cab warmth, as well as higher efficiency. Nice!

[08rx400h]

This is a excellent board, all members are very helpful and answers are informative.

I am lucky to live in warm (hot) weather. Still, when the temp is above 80 and I back the RX400h up from garage to the drive way, the ICE would fire up. I guess an additional EV Mode Only Button would help? I think the new Highlander H has one, when are we going to see it on the RX-h?

[Jim Clark]

This is a excellent board, all members are very helpful and answers are informative.

I am lucky to live in warm (hot) weather. Still, when the temp is above 80 and I back the RX400h up from garage to the drive way, the ICE would fire up. I guess an additional EV Mode Only Button would help? I think the new Highlander H has one, when are we going to see it on the RX-h?

I seriously doubt they would give an option of shutting down the gas engine. Some people would run their batteries down too far, possibly damaging them.

As others stated, the gas engine must warm up when first started to heat the oil, the catalytic converter, and cabin in cold weather. After it is up to operating temperature, the electric motors will do more of the work but the gas engine is still running most of the time. It will shut down when stopped, when coasting downhill, or when driving slowly such as a parking lot.

These are not electric cars, they are "hybrid" gas/electric cars. They have excellent gas mileage and super low emissions for a big SUV. We have been averaging 26 mpg during the winter.

[SOMEONE ELSE'S GOT MY NAME]

This is a excellent board, all members are very helpful and answers are informative.

I am lucky to live in warm (hot) weather. Still, when the temp is above 80 and I back the RX400h up from garage to the drive way, the ICE would fire up. I guess an additional EV Mode Only Button would help? I think the new Highlander H has one, when are we going to see it on the RX-h?

I seriously doubt they would give an option of shutting down the gas engine. Some people would run their batteries down too far, possibly damaging them.

As others stated, the gas engine must warm up when first started to heat the oil, the catalytic converter, and cabin in cold weather.

snip . . .

Hi Jim Clark,

Actually we have installed the EV switch in our Prius, and it has NO effect of battery run down, so there is no danger of messing things up. The on board computers (called ECU's) take into acount how far the batteries are run down. Even w/ the EV switch installed, we notice that when the battery display gets down to the pink bars (the bottom 2), the ICE will come back on. So the HSD cars have engineered that safety feature into the system already. Basically the EV switch allows you to turn the ICE off the last block or 2 before you get to your destination ... or move the car out of the garage, or go move & park around somewhere else, without the ICE kicking on ... or it lets you get up to speed (30-35mph or so) on your early morning commute, before the ICE kicks on. That's all. All this pure EV driving pre-supposes your battery SOC is up nice and high, like up in the green zone, or at least the top of the blue bars.

[08rx400h]

Hi, everyone:

Either with or without EV function, I simply love this vehicle. More importantly, my wife loves it, too!

The auto-awake of the ICE doesn't bother me too much. But, it's louder than my previous RX330. Anyone else feels the same way? I also heard the hybrid system on the new models (LS, GS or even Highlander) has quiter operations, I believe the same will go to the new RX-h.

We got ours about 4 months ago, still under 5K miles, average MPG is between 26 and 27. Hopefully, it will improve even more after total break-in like others claim.

Cheers.

[lexpat]

From what I understand reading this thread, the ICE will run quite a bit after starting in winter to heat up the catalytic converter and the cabin. This makes sense to me.

But I believe I have a different problem with my RX400h. I have noticed a few problems since about October 2007:

- after I started the car at low but not really cold temperatures (i.e. 30s to 40s) the regenerative braking hardly works. When I look at the power gauge at the left when I step on the brakes, it only goes about 10% or so into the blue area, pretty much no matter how hard I step on it. This percentage will increase gradually when the ICE becomes warmer, but even when the ICE is hot (after 50mls highway) it still sometimes only goes to about 50% or so. And even after this 50mls highway stretch and the batteries fully charged, the ICE kicks in right away when I step softly on the pedal to accelerate.

- I also noticed that I used to be able to drive without ICE from my parking garage door to my parking spot (about 100ft) when I return home and the engine is hot, but these days the ICE is always kicks in. Up until October I could accelerate slowly, and as long as the power gauge stayed in the center area the ICE wouldn't kick in. Nowadays it always kicks in, even when I touch the pedal very softly.

- My battery gauge always displays 6 or 7 bars. For many, many weeks I haven't seen anything else on the trip info. I only managed to run with the electric motors a little after my return from a long highway drive, and then I managed to get it to 4 bars when I accelerated very carefully. I also noticed that even though it still displayed 6bars (i.e. not green) the regenerative braking is switched off occasionally (even when I tried to brake softly on a smooth road (no bumps)). I understand that it might switch off if the battery is fully charged, but it shouldn't switch off in this case. I would also expect that the battery would then be drained a little by the electric engines to support the ICE while driving and accelerating, but when I look at the trip info it often seems to charge the battery more than it drains it.

- The mileage of the car is also pretty bad these days. If I drive in the city with fairly long stretches without braking it is probably around 20mpg or so, even if the engine is warm. I think the current reading since I picked it up from the service is 20.6mpg. I used to achieve around 26mpg before the hybrid parts started misbehaving.

I understand if these things happen, when the ICE is cold, but I can't understand why they are happening when the ICE is hot. I had told my Lexus service about this problem when I had the car in for the 20k service, but they said the car is fine and they couldn't find anything wrong with it. After reading all your posts I also tried switching the AC completely off, but that also didn't seem to make a difference.

Do you think that my battery already goes dead after 23k mls? I once had forgotten to switch off the interior light and had to jump start the car the next morning. Could it be that some engine electronics need to be reset?

I would be very happy if some of you could tell me if you experience similar behavior with your car. Any ideas of what you believe could be wrong would also be highly appreciated.

Thanks in advance for your answers.

Just a quick update on my problems, which now seem to be solved.

I went back to the service department of my Lexus dealer and asked them for a road test with the foreman of the shop floor. When I arrived there and explained what I believe the problem was, the foreman said that he probably already knows what's wrong with the car and we even don't have to go for the road test. He asked if my battery was dead at some point in the past, and I confirmed it (I once left the interior light on over night, and the next day I couldn't start the car anymore and had to jumpstart it). So he said that the ECM was most likely the problem and he wanted to reset it so that it starts learning again. He also showed me a printout in which one item (I believe it was the ECM) was incomplete when I brought the car in, and complete after they fixed it. He also showed me a service document that listed some of the symptoms that I experienced, and the remedy for it (resetting of or relearning for the ECM). Since then my Lexus is performing well again, and the mileage is up to 28 to 29mpg from 21 to 22. I am very, very happy again with the car, and believe me, I was pretty upset before.

I was really happy with the service this time, but I am pretty disappointed with my last 20k service where I had already complained about the same problems, and they told me that they read back the diagnostics and couldn't find anything wrong with the car. I wonder what diagnostics they checked this time. Also last time when I picked up the car after the service and got into the car in the pickup garage, a service reminder popped up on the center display informing that a service (don't remember which one) is due. That also made me think how thorough the service was performed in the first place, and how serious they had taken my complaint that the hybrid doesn't work properly anymore.

Does any of you know if I always have to get the ECM reset if I drain my battery? If it has to be done, can it be done by the user or do I always have to take it to the Lexus service?

[Jim Clark]

From what I understand reading this thread, the ICE will run quite a bit after starting in winter to heat up the catalytic converter and the cabin. This makes sense to me.

But I believe I have a different problem with my RX400h. I have noticed a few problems since about October 2007:

- after I started the car at low but not really cold temperatures (i.e. 30s to 40s) the regenerative braking hardly works. When I look at the power gauge at the left when I step on the brakes, it only goes about 10% or so into the blue area, pretty much no matter how hard I step on it. This percentage will increase gradually when the ICE becomes warmer, but even when the ICE is hot (after 50mls highway) it still sometimes only goes to about 50% or so. And even after this 50mls highway stretch and the batteries fully charged, the ICE kicks in right away when I step softly on the pedal to accelerate.

- I also noticed that I used to be able to drive without ICE from my parking garage door to my parking spot (about 100ft) when I return home and the engine is hot, but these days the ICE is always kicks in. Up until October I could accelerate slowly, and as long as the power gauge stayed in the center area the ICE wouldn't kick in. Nowadays it always kicks in, even when I touch the pedal very softly.

- My battery gauge always displays 6 or 7 bars. For many, many weeks I haven't seen anything else on the trip info. I only managed to run with the electric motors a little after my return from a long highway drive, and then I managed to get it to 4 bars when I accelerated very carefully. I also noticed that even though it still displayed 6bars (i.e. not green) the regenerative braking is switched off occasionally (even when I tried to brake softly on a smooth road (no bumps)). I understand that it might switch off if the battery is fully charged, but it shouldn't switch off in this case. I would also expect that the battery would then be drained a little by the electric engines to support the ICE while driving and accelerating, but when I look at the trip info it often seems to charge the battery more than it drains it.

- The mileage of the car is also pretty bad these days. If I drive in the city with fairly long stretches without braking it is probably around 20mpg or so, even if the engine is warm. I think the current reading since I picked it up from the service is 20.6mpg. I used to achieve around 26mpg before the hybrid parts started misbehaving.

I understand if these things happen, when the ICE is cold, but I can't understand why they are happening when the ICE is hot. I had told my Lexus service about this problem when I had the car in for the 20k service, but they said the car is fine and they couldn't find anything wrong with it. After reading all your posts I also tried switching the AC completely off, but that also didn't seem to make a difference.

Do you think that my battery already goes dead after 23k mls? I once had forgotten to switch off the interior light and had to jump start the car the next morning. Could it be that some engine electronics need to be reset?

I would be very happy if some of you could tell me if you experience similar behavior with your car. Any ideas of what you believe could be wrong would also be highly appreciated.

Thanks in advance for your answers.

Just a quick update on my problems, which now seem to be solved.

I went back to the service department of my Lexus dealer and asked them for a road test with the foreman of the shop floor. When I arrived there and explained what I believe the problem was, the foreman said that he probably already knows what's wrong with the car and we even don't have to go for the road test. He asked if my battery was dead at some point in the past, and I confirmed it (I once left the interior light on over night, and the next day I couldn't start the car anymore and had to jumpstart it). So he said that the ECM was most likely the problem and he wanted to reset it so that it starts learning again. He also showed me a printout in which one item (I believe it was the ECM) was incomplete when I brought the car in, and complete after they fixed it. He also showed me a service document that listed some of the symptoms that I experienced, and the remedy for it (resetting of or relearning for the ECM). Since then my Lexus is performing well again, and the mileage is up to 28 to 29mpg from 21 to 22. I am very, very happy again with the car, and believe me, I was pretty upset before.

I was really happy with the service this time, but I am pretty disappointed with my last 20k service where I had already complained about the same problems, and they told me that they read back the diagnostics and couldn't find anything wrong with the car. I wonder what diagnostics they checked this time. Also last time when I picked up the car after the service and got into the car in the pickup garage, a service reminder popped up on the center display informing that a service (don't remember which one) is due. That also made me think how thorough the service was performed in the first place, and how serious they had taken my complaint that the hybrid doesn't work properly anymore.

Does any of you know if I always have to get the ECM reset if I drain my battery? If it has to be done, can it be done by the user or do I always have to take it to the Lexus service?

That's good info, thanks for posting it. Doubt you can do the reset yourself. The diagnostic computer that the dealer hooks up to the car would probably be used to perform that task. I don't know if there's any third party diagnostic software you can get for Lexus's.

[SOMEONE ELSE'S GOT MY NAME]

Oh yea ... you can to it yourself. All you have to do is hook up the Toyota Scangauge ... a measlily $1,500.00 from your online Toyota dealer :P The up side is when the next gen 400h comes out with the Smart Key System, (sks) you can also program your own fobs ... and your neighbors etc ... but the downside is that even even if you're charging $50 a pop to program fobs, it'll take a long time for your scanguage to pay for itself.

[vinovelo]

From what I understand reading this thread, the ICE will run quite a bit after starting in winter to heat up the catalytic converter and the cabin. This makes sense to me.

But I believe I have a different problem with my RX400h. I have noticed a few problems since about October 2007:

- after I started the car at low but not really cold temperatures (i.e. 30s to 40s) the regenerative braking hardly works. When I look at the power gauge at the left when I step on the brakes, it only goes about 10% or so into the blue area, pretty much no matter how hard I step on it. This percentage will increase gradually when the ICE becomes warmer, but even when the ICE is hot (after 50mls highway) it still sometimes only goes to about 50% or so. And even after this 50mls highway stretch and the batteries fully charged, the ICE kicks in right away when I step softly on the pedal to accelerate.

- I also noticed that I used to be able to drive without ICE from my parking garage door to my parking spot (about 100ft) when I return home and the engine is hot, but these days the ICE is always kicks in. Up until October I could accelerate slowly, and as long as the power gauge stayed in the center area the ICE wouldn't kick in. Nowadays it always kicks in, even when I touch the pedal very softly.

- My battery gauge always displays 6 or 7 bars. For many, many weeks I haven't seen anything else on the trip info. I only managed to run with the electric motors a little after my return from a long highway drive, and then I managed to get it to 4 bars when I accelerated very carefully. I also noticed that even though it still displayed 6bars (i.e. not green) the regenerative braking is switched off occasionally (even when I tried to brake softly on a smooth road (no bumps)). I understand that it might switch off if the battery is fully charged, but it shouldn't switch off in this case. I would also expect that the battery would then be drained a little by the electric engines to support the ICE while driving and accelerating, but when I look at the trip info it often seems to charge the battery more than it drains it.

- The mileage of the car is also pretty bad these days. If I drive in the city with fairly long stretches without braking it is probably around 20mpg or so, even if the engine is warm. I think the current reading since I picked it up from the service is 20.6mpg. I used to achieve around 26mpg before the hybrid parts started misbehaving.

I understand if these things happen, when the ICE is cold, but I can't understand why they are happening when the ICE is hot. I had told my Lexus service about this problem when I had the car in for the 20k service, but they said the car is fine and they couldn't find anything wrong with it. After reading all your posts I also tried switching the AC completely off, but that also didn't seem to make a difference.

Do you think that my battery already goes dead after 23k mls? I once had forgotten to switch off the interior light and had to jump start the car the next morning. Could it be that some engine electronics need to be reset?

I would be very happy if some of you could tell me if you experience similar behavior with your car. Any ideas of what you believe could be wrong would also be highly appreciated.

Thanks in advance for your answers.

Just a quick update on my problems, which now seem to be solved.

I went back to the service department of my Lexus dealer and asked them for a road test with the foreman of the shop floor. When I arrived there and explained what I believe the problem was, the foreman said that he probably already knows what's wrong with the car and we even don't have to go for the road test. He asked if my battery was dead at some point in the past, and I confirmed it (I once left the interior light on over night, and the next day I couldn't start the car anymore and had to jumpstart it). So he said that the ECM was most likely the problem and he wanted to reset it so that it starts learning again. He also showed me a printout in which one item (I believe it was the ECM) was incomplete when I brought the car in, and complete after they fixed it. He also showed me a service document that listed some of the symptoms that I experienced, and the remedy for it (resetting of or relearning for the ECM). Since then my Lexus is performing well again, and the mileage is up to 28 to 29mpg from 21 to 22. I am very, very happy again with the car, and believe me, I was pretty upset before.

I was really happy with the service this time, but I am pretty disappointed with my last 20k service where I had already complained about the same problems, and they told me that they read back the diagnostics and couldn't find anything wrong with the car. I wonder what diagnostics they checked this time. Also last time when I picked up the car after the service and got into the car in the pickup garage, a service reminder popped up on the center display informing that a service (don't remember which one) is due. That also made me think how thorough the service was performed in the first place, and how serious they had taken my complaint that the hybrid doesn't work properly anymore.

Does any of you know if I always have to get the ECM reset if I drain my battery? If it has to be done, can it be done by the user or do I always have to take it to the Lexus service?

28 - 29 is mpg outstanding. If I drive very carefully I can get 26 - 28. I have had mine 4 months and while I do not have the exact

same issue as you it is a little similar. The ICE does stop at idle (red lights) OK but seems to have a tendency to kick in way too easily.

On flat and level roads sometimes even feathering the gas pedal the ICE kicks on as I start from a light. Anything less than an 8 - 10

mile ride (even on warm days) kills the mileage.

It just seems like the electric motors are too weak or something to get the vehicle moving to 20 mph or so before kicking in the ICE.

Only when I coast down to a slow speed with the engine at full temperature after a long ride am I able to get extended time with the

ICE off, usually at low < 30 mph speeds (which is a blast when it happens).

One trick I have learned recently by experimentation is to accelerate normally and then lift off the throttle till I see the green

regenerative graphics on the info display and then ever so gently push into the throttle till the electric motor starts (yellow arrows)

but not hard enough to have the ICE kick in. I then notice I can run in electric mode 100% for short distances of 1/4 mile at a

time. Sometimes the ICE begins to kick in again and I repeat lifting off the throttle to get back into electic mode. I've done this

successfully at speeds over 35 MPH, sometimes near 40! If I do not lift all the way off the throttle when I reach my desired speed

the ICE will stay on.

If I do not absolutely baby the thing the mileage drops to the low 20's. If I get on the throttle and have fun (easy to do with all

that power),....I don't even want to know how bad the mileage is.

/Steve

[dadcat]

From what I understand reading this thread, the ICE will run quite a bit after starting in winter to heat up the catalytic converter and the cabin. This makes sense to me.

But I believe I have a different problem with my RX400h. I have noticed a few problems since about October 2007:

- after I started the car at low but not really cold temperatures (i.e. 30s to 40s) the regenerative braking hardly works. When I look at the power gauge at the left when I step on the brakes, it only goes about 10% or so into the blue area, pretty much no matter how hard I step on it. This percentage will increase gradually when the ICE becomes warmer, but even when the ICE is hot (after 50mls highway) it still sometimes only goes to about 50% or so. And even after this 50mls highway stretch and the batteries fully charged, the ICE kicks in right away when I step softly on the pedal to accelerate.

- I also noticed that I used to be able to drive without ICE from my parking garage door to my parking spot (about 100ft) when I return home and the engine is hot, but these days the ICE is always kicks in. Up until October I could accelerate slowly, and as long as the power gauge stayed in the center area the ICE wouldn't kick in. Nowadays it always kicks in, even when I touch the pedal very softly.

- My battery gauge always displays 6 or 7 bars. For many, many weeks I haven't seen anything else on the trip info. I only managed to run with the electric motors a little after my return from a long highway drive, and then I managed to get it to 4 bars when I accelerated very carefully. I also noticed that even though it still displayed 6bars (i.e. not green) the regenerative braking is switched off occasionally (even when I tried to brake softly on a smooth road (no bumps)). I understand that it might switch off if the battery is fully charged, but it shouldn't switch off in this case. I would also expect that the battery would then be drained a little by the electric engines to support the ICE while driving and accelerating, but when I look at the trip info it often seems to charge the battery more than it drains it.

- The mileage of the car is also pretty bad these days. If I drive in the city with fairly long stretches without braking it is probably around 20mpg or so, even if the engine is warm. I think the current reading since I picked it up from the service is 20.6mpg. I used to achieve around 26mpg before the hybrid parts started misbehaving.

I understand if these things happen, when the ICE is cold, but I can't understand why they are happening when the ICE is hot. I had told my Lexus service about this problem when I had the car in for the 20k service, but they said the car is fine and they couldn't find anything wrong with it. After reading all your posts I also tried switching the AC completely off, but that also didn't seem to make a difference.

Do you think that my battery already goes dead after 23k mls? I once had forgotten to switch off the interior light and had to jump start the car the next morning. Could it be that some engine electronics need to be reset?

I would be very happy if some of you could tell me if you experience similar behavior with your car. Any ideas of what you believe could be wrong would also be highly appreciated.

Thanks in advance for your answers.

Just a quick update on my problems, which now seem to be solved.

I went back to the service department of my Lexus dealer and asked them for a road test with the foreman of the shop floor. When I arrived there and explained what I believe the problem was, the foreman said that he probably already knows what's wrong with the car and we even don't have to go for the road test. He asked if my battery was dead at some point in the past, and I confirmed it (I once left the interior light on over night, and the next day I couldn't start the car anymore and had to jumpstart it). So he said that the ECM was most likely the problem and he wanted to reset it so that it starts learning again. He also showed me a printout in which one item (I believe it was the ECM) was incomplete when I brought the car in, and complete after they fixed it. He also showed me a service document that listed some of the symptoms that I experienced, and the remedy for it (resetting of or relearning for the ECM). Since then my Lexus is performing well again, and the mileage is up to 28 to 29mpg from 21 to 22. I am very, very happy again with the car, and believe me, I was pretty upset before.

I was really happy with the service this time, but I am pretty disappointed with my last 20k service where I had already complained about the same problems, and they told me that they read back the diagnostics and couldn't find anything wrong with the car. I wonder what diagnostics they checked this time. Also last time when I picked up the car after the service and got into the car in the pickup garage, a service reminder popped up on the center display informing that a service (don't remember which one) is due. That also made me think how thorough the service was performed in the first place, and how serious they had taken my complaint that the hybrid doesn't work properly anymore.

Does any of you know if I always have to get the ECM reset if I drain my battery? If it has to be done, can it be done by the user or do I always have to take it to the Lexus service?

Here is a link I found to the TSIB on the ISC Learning procedure: http://autozone.kiev.ua/files/Lexus%20400H/Battery/data.pdf

[wwest]

You can probably get the hybrid system to use regenerative braking at a much higher level in wintertime by modifying the OAT sensor. Due to the higher likelihhod of snow or ice on the roadbed less regenerative braking is used, allowed, during cold weather.

But should you do this mod you may be making yourself more subject to loss of directional control....

[wwest]

I suspect that I'll never see "summer-like" MPG, but it will be better than starting at ambient temp in the winter! I've been told to heat it for 3-4 hours, so we're setting a timer to go on about that amount of time before the anticipated morning drive time. My car can get 30MPG in the summer, but was at about 19 in the winter:omg: so I hope to bring it up into the 20's with the heater.

I'm a "worst-case" driver - no garage, and only about a 5-mile commute. I never even got the car warmed up last winter on the drive into work, so I think this will help. I'll let you all know!

My RXes heating blower will not come on automatically until the engine coolant temperature rises to 130F, and that generally happens within a mile, ~1/17th of a gallon of fuel (20.59 cents), of leaving the attached non-heated garage.

So what would it cost to bring the engine block up to 130F using a block heater vs not...??

And how much of that 20.59 cents went toward simply moving the RX for that distance vs heating the block and thereby the engine coolant??

Maybe 10%, 2.059 cents...?

Hmmm..

No, wait...

The engine block is CONTINUOUSLY heated, to ~200F yet.

So, until the coolant heat rises to the point wherein the EXCESS is dumped overboard isn't that HEAT free of cost...??

It seems to me that the only time there is "value" in the engine coolant heat is for cabin heat, otherwise ALL of it is THROWN overboard.

That can't be right...or can it...??

That would mean that the cost savings for pre-heating the engine blocking would be ZILCH,...or maybe even NEGATIVE.

And then there is the catalyst, that MUST be heated to something like 800F before becoming fully operational. Does pre-heating the engine block allow more of the "initial" excess heat derived from "fuel burn" to flow into the exhaust and thereby help to heat the catalyst sooner?

Wow, too many variables for me, 'way too many.

[SOMEONE ELSE'S GOT MY NAME]

28 - 29 is mpg outstanding. If I drive very carefully I can get 26 - 28. I have had mine 4 months and while I do not have the exact

same issue as you it is a little similar. The ICE does stop at idle (red lights) OK but seems to have a tendency to kick in way too easily.

On flat and level roads sometimes even feathering the gas pedal the ICE kicks on as I start from a light. Anything less than an 8 - 10

mile ride (even on warm days) kills the mileage.

It just seems like the electric motors are too weak or something to get the vehicle moving to 20 mph or so before kicking in the ICE.

Only when I coast down to a slow speed with the engine at full temperature after a long ride am I able to get extended time with the

ICE off, usually at low < 30 mph speeds (which is a blast when it happens).

One trick I have learned recently by experimentation is to accelerate normally and then lift off the throttle till I see the green

regenerative graphics on the info display and then ever so gently push into the throttle till the electric motor starts (yellow arrows)

but not hard enough to have the ICE kick in. I then notice I can run in electric mode 100% for short distances of 1/4 mile at a

time. Sometimes the ICE begins to kick in again and I repeat lifting off the throttle to get back into electic mode. I've done this

successfully at speeds over 35 MPH, sometimes near 40! If I do not lift all the way off the throttle when I reach my desired speed

the ICE will stay on.

If I do not absolutely baby the thing the mileage drops to the low 20's. If I get on the throttle and have fun (easy to do with all

that power),....I don't even want to know how bad the mileage is.

/Steve

Welcome to the world of "Pulse & Glide" :P ... or P&G as we 'hypermilers' call it.

Some have gotten over 40mpg averaged over an entire tank full in the hyhi ... so someone may be doing it already in the 400h but we just don't know about it yet.

How else could I have beat the EPA by over 25mpg in my Prius ?!?

Over 700 miles, on 10 gallons ... not too shabby?

[lexpat]

Here is a link I found to the TSIB on the ISC Learning procedure: http://autozone.kiev.ua/files/Lexus%20400H/Battery/data.pdf

Thanks a lot for this link, dadcat. This is exactly the procedure that the foreman showed me. But at that point I couldn't read everything. Now I know that I have to get this procedure performed at my friendly Lexus service everytime the battery voltage drops below 7V. This is really helpful information. Thanks, I really appreciate it.

[SOMEONE ELSE'S GOT MY NAME]

My RXes heating blower will not come on automatically until the engine coolant temperature rises to 130F, and that generally happens within a mile, ~1/17th of a gallon of fuel (20.59 cents), of leaving the attached non-heated garage.

So what would it cost to bring the engine block up to 130F using a block heater vs not...??

And how much of that 20.59 cents went toward simply moving the RX for that distance vs heating the block and thereby the engine coolant??

Maybe 10%, 2.059 cents...?

Hmmm..

No, wait...

The engine block is CONTINUOUSLY heated, to ~200F yet.

So, until the coolant heat rises to the point wherein the EXCESS is dumped overboard isn't that HEAT free of cost...??

It seems to me that the only time there is "value" in the engine coolant heat is for cabin heat, otherwise ALL of it is THROWN overboard.

That can't be right...or can it...??

That would mean that the cost savings for pre-heating the engine blocking would be ZILCH,...or maybe even NEGATIVE.

And then there is the catalyst, that MUST be heated to something like 800F before becoming fully operational. Does pre-heating the engine block allow more of the "initial" excess heat derived from "fuel burn" to flow into the exhaust and thereby help to heat the catalyst sooner?

Wow, too many variables for me, 'way too many.

mwest, you brought up interesting factoids ! ... and even so, there are other variables & motives for using an EBH. For example in sub zero conditions, an EBH can mean the difference between the vehicle starting or not. Who'd want to have to replace a freeze plug, if your coolant expanded & pushed one out? And between your older RX, versus the hybrid version, there are other variables. With much of a hybrid's mpg improvements being due to the electric motors, traction battery temperature management becomes important. The EBH warming the block/coolent allows the cabin heater to warm the batteries quicker. Our 400h gets only around 15mpg during the 1st 10-12 minutes, but with the EBH, the 400h is capable of going over 30mpg within the 1st minute. Etc etc.

[wwest]

My RXes heating blower will not come on automatically until the engine coolant temperature rises to 130F, and that generally happens within a mile, ~1/17th of a gallon of fuel (20.59 cents), of leaving the attached non-heated garage.

So what would it cost to bring the engine block up to 130F using a block heater vs not...??

And how much of that 20.59 cents went toward simply moving the RX for that distance vs heating the block and thereby the engine coolant??

Maybe 10%, 2.059 cents...?

Hmmm..

No, wait...

The engine block is CONTINUOUSLY heated, to ~200F yet.

So, until the coolant heat rises to the point wherein the EXCESS is dumped overboard isn't that HEAT free of cost...??

It seems to me that the only time there is "value" in the engine coolant heat is for cabin heat, otherwise ALL of it is THROWN overboard.

That can't be right...or can it...??

That would mean that the cost savings for pre-heating the engine blocking would be ZILCH,...or maybe even NEGATIVE.

And then there is the catalyst, that MUST be heated to something like 800F before becoming fully operational. Does pre-heating the engine block allow more of the "initial" excess heat derived from "fuel burn" to flow into the exhaust and thereby help to heat the catalyst sooner?

Wow, too many variables for me, 'way too many.

mwest, you brought up interesting factoids ! ... and even so, there are other variables & motives for using an EBH. For example in sub zero conditions, an EBH can mean the difference between the vehicle starting or not. Who'd want to have to replace a freeze plug, if your coolant expanded & pushed one out? And between your older RX, versus the hybrid version, there are other variables. With much of a hybrid's mpg improvements being due to the electric motors, traction battery temperature management becomes important. The EBH warming the block/coolent allows the cabin heater to warm the batteries quicker. Our 400h gets only around 15mpg during the 1st 10-12 minutes, but with the EBH, the 400h is capable of going over 30mpg within the 1st minute. Etc etc.

In my years in MT in the early to mid-sixties I more often used a dipstick type engine oil heater but sometimes a coolant heater, and then only during sub-freezing weather times. None of these measures worked in Alaska since they didn't prevent the ATF nor PS fluid from turning to SLUSH overnight. I would often go outside and start the car and then go have breakfast while the ATF and PS fluid turned back into a LIQUID.

[Grumbles2]

Want to try an intresting experiment? The ICE does in fact run more duting colder ambient temperatures.

First reason is to keep the coolant above the magic 168 degrees that being the min temp that the engine has its most complete combustion. If the temp drops below that when the ICE starts it would put out excessive air pollution because it would go back into fuel enrichment mode like when its cold on first start up. When its colder out the engine must run longer to keep the temp up.

Second reason and the intresting experiment. Next time its cold out and you are sitting still, mess with the inside heater temperature setting. You will notice that when you move the temperature up and down the ICE will turn on and off. Reason?

As the A/C Heater control unit sees your temperature input it will turn the ICE on and off because the heater core removes heat from the engine to heat the interior of the vehicle. I was waiting to pick up someone, outside temp was 40 degrees, I noticed that when I would adjust the temperature above 71 degrees the ICE would come on and when I adjusted it below 71 degrees it would turn off. Yall check it out and let me know what yours does. :)