Injectors?

[CeeBee]

Funny. Today my RX started giving me probs. I have a 99 RX300 with a ton of miles on it. (178k) Everything is original tranny, engine, all the good stuff... i have only replaced a few sensors and replaced an exhaust gasket in 4 years... I drive it like a freekin supra or something, but i take good care of it when i turn it off... Today i filled her up w/89 like usual and not more than 5miles later she began sputtering... Naturally i floored it... severe power loss... wouldnt really go to high on the tachs, shifting at around 3,500 with the pedal pinned.. when i stopped, the engine had a rumble that shook the car... it continued when i pulled off until 2,500 where it smoothed out but still had no power... Make any sense?

[TunedRX300]

Go to Autozone and get a free read for CEL code, sounds like you may have a bad coil.

[RX in NC]

Some of your symptoms could also indicate a blown head gasket. Check your coolant level - if you've lost most of it, you've probably blown your head gasket.

[tmastres]

Funny. Today my RX started giving me probs. I have a 99 RX300 with a ton of miles on it. (178k) Everything is original tranny, engine, all the good stuff... i have only replaced a few sensors and replaced an exhaust gasket in 4 years... I drive it like a freekin supra or something, but i take good care of it when i turn it off... Today i filled her up w/89 like usual and not more than 5miles later she began sputtering... Naturally i floored it... severe power loss... wouldnt really go to high on the tachs, shifting at around 3,500 with the pedal pinned.. when i stopped, the engine had a rumble that shook the car... it continued when i pulled off until 2,500 where it smoothed out but still had no power... Make any sense?

It sounds very similar to a faulty coil. Since the RX's have individual coils for each plug when one goes out it's like (is) being down a cylinder. Unfortunately I've had this happen twice and the car is still driveable even though its runs rough, it doesnt stall but feels like you're towing a freight train with no power to speak of.

Part is about $100.

[CeeBee]

Exactly... it doesnt stall but seems like it will at any second.... Doesnt sound like DIY... How can i tell which coil if any are bad? I cleaned the MAF and changed the oil... same result... The more i think about it, i may have left the engine running when i filled up yesterday... could that have clogged something??

[TunedRX300]

Exactly... it doesnt stall but seems like it will at any second.... Doesnt sound like DIY... How can i tell which coil if any are bad? I cleaned the MAF and changed the oil... same result... The more i think about it, i may have left the engine running when i filled up yesterday... could that have clogged something??

That is why CEL code needs to be read, did you go to Autozone?

[CeeBee]

Exactly... it doesnt stall but seems like it will at any second.... Doesnt sound like DIY... How can i tell which coil if any are bad? I cleaned the MAF and changed the oil... same result... The more i think about it, i may have left the engine running when i filled up yesterday... could that have clogged something??

That is why CEL code needs to be read, did you go to Autozone?

ok...i went to Autozone today.... They told me i have a misfire on cylinders 3 and 4... a bad MAF sensor... and a bad IAT sensor.. Where do i start??

[tmastres]

ok...i went to Autozone today.... They told me i have a misfire on cylinders 3 and 4... a bad MAF sensor... and a bad IAT sensor.. Where do i start??

This will depend entirely on the time you have available and your aptitude as a shadetree mechanic. I believe the MAF (mass air-flow) and IAT (intake air-temp) sensor are the same thing of part of the same sensor . I do NOT know this for a fact but I believe that info should be available somewhwere easily. I'd replace that first and see what happens. If you've still got the problem I'd first check the sparkplugs. Since you've got both 3 and 4 bad that means a trip to the back of the engine (not a friendly place). I find it virtually impossible to get my hands and tools back there but it can be done with the right tools and a ton of patience. If the plugs are good then I'd replace the coil-packs which sit on top of the spark plugs.

I've yet to actually do the replacement of the coil pack myself (physically) but my Mech got them for about $100 and only charged me $65 to install each time so I'm guessing its not all that complicated (again I could be wrong). I only have the weekends to wrench on cars and I've already got 4 to maintain so anything that takes more than 2 hrs to do goes to the shop.

As an aside, the 2 times my coil packs went bad there was no warning. One day i put the car in the parking garage at work running fine and that evening when I started it up it felt like an army of Gnomes were trying to tip my car over. The second time I was actually idling at a light and next thing you know...

Unfortunately it makes me a bit cautious nowadays I'm just waiting for the rest to go bad.

Good luck and if you go it yousrself, get a copy of the RX 300 shop manual that was available on this forum as a PDF a few months ago, its obviuosly a great resource.

[Grumpa72]

Are you sure you just didn't get a load of bad gas? Five miles after a fill up and all of sudden things go crazy? Too coincidental for me. I would start by draining the tank and refilling with a high quality name brand gas just to see. this would be a far faster method of troubleshooting than replacing coils, MAF sensor, IAT valve, etc.

[tmastres]

Are you sure you just didn't get a load of bad gas? Five miles after a fill up and all of sudden things go crazy? Too coincidental for me. I would start by draining the tank and refilling with a high quality name brand gas just to see. this would be a far faster method of troubleshooting than replacing coils, MAF sensor, IAT valve, etc.

I'm not sure that bad gas would cause a trouble code fo rthe MAF and a misfire in only 2 cylinders but hey, who knows.

I'm putting my money on bad coil packs( or plugs) just because it sounds like an exact description of what it felt like when mine went bad.

[TunedRX300]

Cleaning IACV can also be a simple DIY.

http://us.lexusownersclub.com/forums/index...showtopic=30723

I doubt MAF and IACV can be both clogged at the same time, most likely they are side affects of bad coils.

[CeeBee]

Cleaning IACV can also be a simple DIY.

http://us.lexusownersclub.com/forums/index...showtopic=30723

I doubt MAF and IACV can be both clogged at the same time, most likely they are side affects of bad coils.

I plan to go under the hood again this weekend... Im going to clean the throttle body and change the plugs.. Is there a way to visually inspect the coils to see which if any are bad??

[TunedRX300]

Cleaning IACV can also be a simple DIY.

http://us.lexusownersclub.com/forums/index...showtopic=30723

I doubt MAF and IACV can be both clogged at the same time, most likely they are side affects of bad coils.

I plan to go under the hood again this weekend... Im going to clean the throttle body and change the plugs.. Is there a way to visually inspect the coils to see which if any are bad??

Swap a bad coil with a good one and read the code again.

[tmastres]

I plan to go under the hood again this weekend... Im going to clean the throttle body and change the plugs.. Is there a way to visually inspect the coils to see which if any are bad??

If you havent done so already I'd invest in a code reader so you'll be able to read and reset your codes right there in the driveway.

Cleaning the IACV is a good idea and probably worth doing but usually the rough idle a sticky one causes is not as severe as you've mentioned.

I'd be very interested in your findings if you can determine which coils are bad visually (since I anticipate doing this myself in the future)

PS you may already have a great set of tools but after reading many posts regarding access to the rear plugs I suggest having several types of extenders and knuckle joints available to extract the plugs.

Good Luck! :)

[RX in NC]

Accessing those three rear spark plugs is a killer and if you have huge hands like I do, you have no chance of getting back there and still having enough room to manipulate the socket wrench extensions. Before I changed our recently-sold RX300 plugs last October, I made sure my five-foot-two small-handed neighborhood buddy was standing by to do the dirty work on the three rear plugs. After about an hour, he got the old plugs out and the new plugs in. So be forewarned....

The front three plugs are cake. I had the old plugs out and the new plugs in inside ten minutes.

[TunedRX300]

Accessing those three rear spark plugs is a killer and if you have huge hands like I do, you have no chance of getting back there and still having enough room to manipulate the socket wrench extensions. Before I changed our recently-sold RX300 plugs last October, I made sure my five-foot-two small-handed neighborhood buddy was standing by to do the dirty work on the three rear plugs. After about an hour, he got the old plugs out and the new plugs in. So be forewarned....

The front three plugs are cake. I had the old plugs out and the new plugs in inside ten minutes.

Just remove the intake throttle body to make more room.

[lenore]

make sure you use NGK or Denso plugs, warning do not use Bosch plugs, you will be sorry....

[Karl K]

My guess is that once you get the engine to run on all cylinders, by raplacing the plugs and or coils, the MAF and IACV will function normally again.

Do the most obvious things first.

Good luck,

Karl

[CeeBee]

WTF!!!!! what a apin in the a** those rear plugs are.... Thanks guys for all your help on that topic... otherwise i probably woulda given up... So, I changed the plugs.... moved the coils around to see if differnt cylinders misfired or what.... I ended up driving the car for almost 2hrs...I had some errands do to before the old lady came home with the other car... Befor i could make it to Autozone She lost almost all power.... She refused to stall but wouldnt go above about 2k rpms.... If i gave it gas it would go into a heavy hesitation, sputtering(sounded like from underneath not behind).. I give!! She just barely made it to the shop about a mile away... Im waiting for the call... got my fingers crossed... i really hope she isnt dying on me... after all she has 188K on original motor and tranny... :cries:

[tmastres]

WTF!!!!! what a apin in the a** those rear plugs are.... Thanks guys for all your help on that topic... otherwise i probably woulda given up... So, I changed the plugs.... moved the coils around to see if differnt cylinders misfired or what.... I ended up driving the car for almost 2hrs...I had some errands do to before the old lady came home with the other car... Befor i could make it to Autozone She lost almost all power.... She refused to stall but wouldnt go above about 2k rpms.... If i gave it gas it would go into a heavy hesitation, sputtering(sounded like from underneath not behind).. I give!! She just barely made it to the shop about a mile away... Im waiting for the call... got my fingers crossed... i really hope she isnt dying on me... after all she has 188K on original motor and tranny... :cries:

Hey, we tried to warn you :D Let me know what the Diagnosis is. Thanks!

[blk_on_blk]

Hey CeeBee, did you ever get an end result? I just had a similar thing happen to me today. The RX was running fine when I parked it at work. I went in for about 2 hours for a meeting, and when I started it up, it ran rough like someone pulled the wiring off a coil pack or something. I'm getting a code reader from my friend at work tomorrow, so I'll do a little diagnosing, but I'm putting my money on a coil pack (or two).

Presuming it's a coil pack, anyone know a good vendor? Or is this a dealer part?

[TunedRX300]

I forgot to recommend that you can always buy a good coil from Park Lexus in Plano, for spare or to swap around.