wwest

Fix/repair/adjust the hot water flow control valve in the engine compartment at the top center of the firewall. As you change the temperature control from maximum hot to maximum cold the valve control cable coming through the firewall, driven by the blend door servomotor, should move the valve from fully open to FULLY closed.

I would normally say replace it only if it is clogged and would need to be pressure cleaned, but at 140,000 miles your strainer has earned a rest.

:chairshot: Oops, sorry, this can be deleted.

Someone please step in and HELP if I am truly wrong. It has always been my understanding that the lowest emissions are obtained when the A/F mixture is optimized to the point that virtually all fuel and oxygen is burned in the process of combustion. Therefore any detectable oxygen flowing past the A/F mixture controlling oxygen sensor would imply a "lean burn" mixture ratio. Oh, maybe I see now....looked at your chart again. I think, insofar as lowest emissions, the mixture should be in the range of 14.7:1, right in the middle of the A/F (oxygen) sensor signal range/resolution as shown in the chart. Again, someone correct me if this is wrong but isn't the A/F mixture desireable for peak HP, performance,in the range of 12:1 and above, just at the edge or slightly above the range of the A/F mixture sensor shown on the chart? One of the charts via the link shows a vehicle accelerating, near or at WOT, to ~55MPH. During the acceleration it can be seen that the mixture is being enriched to the point that the A/F mixture (oxygen) sensor goes to the edge (0.512x5=2.560 volts) of its range/scale if not actually off-scale. Obviously it will be in the "region" wherein the MAF/IAT must be relied upon. But what I find most interesting, REALLY INTERESTING, is the graph of the acceerator position as it goes from idle, fully released, to WOT in order to quickly accelerate up to 60MPH. The chart shows the pedal going slightly open, then closing completely, then to a more open position than before, back to idle again, and then finally to WOT. I cannot imagine a person "dithering", at least not intentionally, the gas pedal in the manner indicated. I assume that this signal is sent to the OBD-II connector via the engine/transaxle ECU as a result of its sensing. A/D conersion, of the actual signal for the accelerator pedal absolute position sensors. How many of you are aware of the numerous posts concerning inordinant transaxle downshift delays? Talk about how to thoroughly confuse the engine/transaxle ECU's downshift firmware algorithm....!!

I don't doubt that providing more, and/or a "freer" intake airflow path would normally, certainly back in the days of carburation, result in a higher PEAK level of engine HP/torque. But then again I also know, am very certain, that the MAF/IAT module is there in the intake airflow path to provide a method of controlling the A/F mixture ratio when the engine is operating above the A/F mixture sensing capability of the upstream oxygen sensor. The computational equation for this must be "fixed" at the factory based on the resistance to flow and the cross-sectional area of the intake at the point of measurement, at the MAF/IAT module. Think of it this way, in boring out the intake you are more or less, in effect, providing an air leak into the intake manifold. Yes, more peak intake airflow, but with a resulting leaner mixture than the factory intended. The oxygen sensor between the engine and catalytic converter is used to determine proper A/F mixture ratios insofar as lowest emissions are concerned. The oxygen sensor is like an on/off switch, function, it can be used to tell you that the exhaust has an oxygen content, not how much or high that oxygen content happens to be. The engine/transaxle ECU determines the proper ratio by slightly "dithering" the A/F mixture up and down in rapid sequence, resulting in the oxygen sensor output going "on and off" in the same sequence. If the oxygen sensor output doesn't "oscillate" in synchronization with the "dithering" rate of the A/F mixture then the ECU will go into "learn" mode in order to get the A/F mixture into the "sweet spot". The problem arises when you ask the engine to produce an output power level which cannot be achieved while at the same time obtaining the lowest possible emissions level, the mixture must be enriched above the level desireable for lower emissions. So, when you ask for acceleration the engine/transaxle ECU starts disregarding the A/F mixtuire oxygen sensor and begins controlling, enriching, the mixture based strictly on the MAF/IAT signal levels. Bore out the idle air bypass "channel" and the system will quite quickly "learn" a new setting for the idle air bypass control solenoid. The same would be true of the overall intake path just as long as the system can use the proper A/F mixture resulting in the lowest emissions, say while cruising along on a level roadbed at a constant speed. But once the need arises to enrich the mixture in order to produce the engine's peak HP rating the ECU will fall back on the factory default equation using the MAF/IAT signals only.

Wonder if the future holds a possibility for an LS with the GSh drive train..... Who would have ever thought Toyota would end up using their hybrid synergy technology simply to SUPERCHARGE the LS...

I don't doubt that providing more, and/or a "freer" intake airflow path would normally, certainly back in the days of carburation, result in a higher PEAK level of engine HP/torque. But then again I also know, am very certain, that the MAF/IAT module is there in the intake airflow path to provide a method of controlling the A/F mixture ratio when the engine is operating above the A/F mixture sensing capability of the upstream oxygen sensor. The computational equation for this must be "fixed" at the factory based on the resistance to flow and the cross-sectional area of the intake at the point of measurement, at the MAF/IAT module. Think of it this way, in boring out the intake you are more or less, in effect, providing an air leak into the intake manifold. Yes, more peak intake airflow, but with a resulting leaner mixture than the factory intended.

Have you thought about port and polishing the intake manifold in addition to throttle body? Reaming out, increasing the throttle bore, and/or polishing the throttle body will only be effective at WOT. Adding a 15 cent 1/4 watt 200 ohm resister in series with the IAT will add 10% to factory HP/torque anytime the engine is under pulling load, the torque converter lockup clutch is disabled. 400 ohms might even yeild 20%. Sorry I am not interested to fool ECU to think inlet air is cooler on a temporarily basis. I am interested either lower the real air temperature or increase flow. Not trying to debate because I know people will get real emotional. If someone can show me gain on the dyno chart, I am interested. I do not agree/disagree with Pheonix's posting on this thread, just want to verify his claim of 25bhp gain by port and polishing on 1mzfe. http://www.clublexus.com/forums/showthread.php?t=179583 "....not interested...." "...on a temporarily basis..." "....I am interested...." "...or increase flow...." Increased flow can only "happen" at WOT,.....on a temporary basis...at all other times the throttle plate is restricting flow beyond any measures you might add to improve flow. The very same problem K&N has, unless the throttle is wide open and the engine is near top RPM who cares if the OEM filter restricts the flow by ~7%. So, if you leadfoot it a LOT, (hopefully only on the track) improved airflow will be of help. That's also why most race cars use K&N, enough time at or near WOT to make it count. The aforementioned resistor would result in a richer mixture anytime the engine is under acceleration loads/loading.

Have you thought about port and polishing the intake manifold in addition to throttle body? Reaming out, increasing the throttle bore, and/or polishing the throttle body will only be effective at WOT. Adding a 15 cent 1/4 watt 200 ohm resister in series with the IAT will add 10% to factory HP/torque anytime the engine is under pulling load, the torque converter lockup clutch is disabled. 400 ohms might even yeild 20%.

Experimentation was totally inconclusive. I didn't dare, no "braves", do a falsification beyond ~10%. Since the effect seems to be only during acceleration or under pulling loads, times when the load-up clutch is disengaged, I wasn't surprised at not seeing any FE effects in either direction. The truth can likely only be found on a dyno. I don't think I would try to run lean in the long term and thereby (I suspect) put my catalytic converter at risk. On the other hand if one wanted a little extra BOOST then a slightly higher enrichment over OEM might not do any harm.

I'll vote for it being a filler tube fitting plug. The one's I have found in Ford sumps in the past were plastic but the shape is much the same. The Ford "plugs" were obviously designed to be removed (long "stem" Handle)before final installion but for some reason were not. Check the OD of the ATF filler tube and see if they aren't the ~same.

Easiest way to check is to see if there is a puddle of water left on the ground after a day of A/C use. Go to airsept.com and read up on their EED, electronic evaporator dryer. Google for: demist denso odor

I have noticed that the spoiler on the newer RXes does not completely, as completely, cover the rear "window" as it does on my RX300, possibly due to the additional slant. As a result Lexus may be using the moisture, rain dropplet, resistance coating on the rear as they have on the front windshield from the get-go.

The QUEST... Determine why these transaxles are failing prematurely at ~70,000 miles or so. Since the viscous fluid within the viscous clutch/coupling must self-heat in order to become functional, begin "locking" the center diff'l, I was suspicious that this heat might be at least one of the causative factors. Apparently not.

When the engine is idling or operating at a relatively constant RPM, highway cruising at a relative constant speed, the front oxygen sensor, the one upstream of the catalytic converter, is the sole controlling factor for A/F mixture ratios. Above idle and during acceleration, engine under "load", the A/F mixture is enriched above the level wherein this oxygen sensor signal can be valid so control of the A/F mixture is now the result of the MAF/IAT module signal output. At ~72F intake airflow temperature the IAT has a resistance of ~2000. Adding a 200 ohm 1/4 watt resister in series with the IAT signal, pin 4 or 5 of the connector, will make the engine/transaxle ECU compute the proper A/F mixture ratio based on a FALSE intake temperature. Adding the 200 Ohm resister will falsify the signal such that the computation will be made as if the intake air temperature is quite a bit COLDER (colder air is denser) than reality resulting in an inordinantly richer mixture, more HP/Torque (~5%), than was originally programmed at the factory. Obviously boring out the throttle body will result in more air volume flowing into the intake manifold than the factory computation provided for at a given level of MAF signal voltage. Thus the factory computation would result in a somewhat leaner mixture during acceleration/engine "loading" situations. More fuel economy due to less HP/torque available for acceleration. If FE is the goal then a 20k ohm resistor across the IAT signal wires will do the trick.

Today I opened the fill plug for the PTO on my 2001 AWD RX300 (56,589 miles). The transfer case lubricant is pristine, absolutely no indication of overheating, no burned odor, no contamination, etc. So the VC is NOT, indirectly or otherwise, the source of the burned and contaminated ATF in the nearby diff'l case.

How did you compensate for the MAF/IAT sensor signals...?? The MAF measures the airflow at/near the center of the cross-sectional area of the throttle opening. The computation of actual intake airflow will therefore be based on the factory "as shipped" cross-sectional area of the throttle body. The result of your modification, seemingly, would be a leaning of the A/F mixture since more airflow is entering the intake manifold than the factory computation "predicts". In any case I can't see that your mod would have any positive effect, if any, except at WOT where intake airflow would be limited were it not for you "mod". Same problem K&N has. I suspect RX owners could obtain much the same effect with a simple 1/4 watt resistor (15 cents??) to modify the MAF/IAT signal.

Good advice ... I think I do have a small leak in my front left tire ... it's been loosing air ... I just didn't think that would have caused something like this. I'll check it out. Thanks! :) rlin78, Thanks for the update. I'll see about cleaning up my sensors and checking my tire pressure. I've turned the traction control off, so hopefully it will keep the warning from going off. We had a good Lexus dealership, but there is also an independent place here that specializes in Lexuses, so I'll give them a try. Thanks everyone! :) Either your stearing wheel position sensor or your yaw sensor is failing. My vote would be the yaw sensor.

Okay, I've made "my" decision. I'll be buying a new RX400h, but probably wait until late fall, 2007 model, in hopes it gets the DFI engine. The RX350 was very tempting since it has the VC and can therefore be easily converted to rear biased AWD. The killer for that purchase was also due to the lack of the DFI engine.

Just went back and reread your post and it appears your complaint more concerns the way the system reacts to NEW temperature setpoints than the way it acts, reacts, on it own once the temperature setpoint is reached. In automatic mode when you first get into the car and the cabin is coolish, significantly below your setpoint, the outlet airflow will always be from the footwell outlets. That airflow might be fairly warm, even hot, but you will not be so sensitive to that as you might were it coming from the dash vents. AS the cabin air temperature rises and gets to within ~5-8 degrees of your setpoint the system will switch to footwell/dash combined. Once within 2-3 degrees the primary airflow will be via the dash outlets only. If the predominant radiant effects to your body are on the coolish side this "cool" and dry airflow will definitely be discomforting. So you move the setpoint up a few degrees, say 72F to 74F. Since Lexus is so NOISE adverse the most likely system response is to raise the temperature of the system air outflow while leaving the blower on the lower speed it went to back when the cabin first "reached" the setpoint. AND... A move from 72F to 74F would often not be enough difference to warrant the system reverting to footwell outlet mode. So now you're setting there being discomforted by uncomfortably warm airflow to your face and upper body. And remember, even if your changed temperature setpoint is of enough difference to warrant the system switching to footwell mode, once the cabin reaches or approaches the new setpoint you will be back to square one. Unless you actually need the A/C cooling purposes, not just for dehumidification of the incoming airstream, keep the system out of "cooling" mode by over-riding it into footwell mode. It would also help somewhat if you turn the A/C off entirely, the cooling aspects, the refrigerant compressor. My 2001 RX300 has a c-best setting that will allow the driver to disable the A/C indefintely simply but manually turning it off one time. You can bet that my C-best settings are such that the A/C NEVER cycles, not even in defrost/defog/demist mode, unless I wish it too.

Hot left, cool right.... Your car has two sunlight radiant heating level sensors, detectors, one on the far right at the bottom of the windshield, and another for the driver, on the far left. If the sun happens to be shining BRIGHTLY on one but not the other the sunshine side might get significant cooler airflow than the opposite side. ".....constant adjustment....." While I sorta buy into the "dirty" cabin temperature sensor delaying the functionality of the climate control I don't believe that even if true the delay would be such that it would be noticeable, let alone cause the symtoms yours exhibits. The Lexus climate control is fast acting, reacting, for radical differences between your temperature setpoint and the actual cabin temperature, but the closer the cabin temperature gets to your setpoint the longer the designed in time constants become. To do otherwise would be counter to Lexus "pesonna" and would undoutedly be discomforting. "...neither of which...." Acura uses the same climate control vendor as Toyota and I have seen no end of complaints of sudden windshield fogging and just plain "how do I keep the windows from fogging up" questions from owners. As for Audi (and Porsche) it is my understanding that their (Bosch) biggest problem in this "venue" is that they will quite thoroughly CHILL the windshield on the hottest summer day and that subjects their owners to sudden windshield fogging on the outside surface.

As I understand it with the introduction of the 2001 models the "mechanical" LSD option was deleted. I was told that the VSC/Trac system in my 2001 had a mode wherein it used braking to simulate, virtualize, an LSD. It was my understanding at the time that in purchasing the 2001 AWD RX300 I had acquired a vehicle with virtual LSDs at the front, center, and rear diff'ls. From the way the online repair manual reads, other than engine oil, I would not suggest anything other than the specific fluids recommend by Toyota/Lexus.

It is my personal suspicion that over the long term, ~35,000 miles in my case, the viscous fluid within the PTO begins to congeal thereby resulting in some level of continuous locking of the center diff'l. If the diff'l tends to lock when it should not then the 90 weight lubricating oil in the PTO will begin to overheat due to the additional driveline stress. A few years ago my son-in-law happened to put the wrong size tires on the front of his MY2000 Chryler T&C AWD minivan. They were going skiing and he wanted to be able to fit, use, the tire chains he had bought for the factory tire/wheel combination. Within about fifty miles the ring gear within the PTO began to shed teeth. The best way I can describe just how much, to what level, the 90 weight in that PTO was overheated is by explaining why the gas company was around here with their "sniffer" a few days after the old PTO went into the garbage container. Apparently the gas company had gotten several calls complaining of a horrid odor around the neighborhood. If the VC on the RX300 should begin to congeal after ~35,000 miles then the result is inevitable. Which reminds me, maybe I should go home tonight and open the PTO's 90 weight fill plug and check the odor of the 90 weight in there. But no, really, I think the fault lies with the sum of many small engineering errors. A) The firmware switch to AGL, Aggressive Shift Logic. For city stop and go driving that would likely double the number of times the transaxle changes gears for a specific distance. B) The (apparent) fact that a portion of the ATF remains within the diff'l "sump" and is not readily circulated to the main transaxle case where it would be pumped through the ATF cooling system. C) The extra heating of the ATF within the diff'l case as a result of the VC being heated from disparate front to rear driveline rotational speeds. I fully suspect that by mid to late 2000 the engineers had put two and two together and knew why the RX300 transaxles were beginning to fail prematurely. So the temporary fix was to adapt the ML320 AWD system of braking to allocate, apportion, engine torque front to rear and side to side. I was told that this was why the mechanical LSD was removed from the option list for 2001 and later models. Every RX buyer was to now get one, abet a virtual one, for "free". I suspect that had they gone ahead and also removed the VC back in 2001 as they finally did for the RX330 then my ATF wouldn't have looked and smelled burned at 35,000 miles.

Engine lubricating oil is being constantly exposed to and contaminated by the byproducts of combustion. I only changed the anti-freeze in my 1992 LS400 about two years ago. The freeze level was still good as was the Ph. But the coolant, while still a definite pink color, was beginning to look a little murky. ATF has two functions only, to act as a hydraulic fluid and as a lubricating oil. Three, now that I think of it, the ATF also serves to carry away the heat load of many of the components. So, the only source of ATF contamination is due to the wear rate of the clutch frictional surfaces and the the ATF is specifically formulated so it does not hold these in suspension as is the case with motor.

Then tell me, please, why is it that I can introduce you to at least 6 LS400 owners ( 1/91, 3/92s, 1/95, and 1/98) all with mileage well above 100k, one above 150k, that have NEVER had reason to drain, flush, or replenish their ATF? Even in the old clunky late 1960's and early 1970's Fords I drove for well over 200k miles, I did only two ATF change-overs, and those were the result of DIY overhauls in excess of 100K miles. I have always checked/inspected the ATF during very oil change, which is why I can tell you that the ATF in my 2001 AWD RX300 looked perfectly pristine until suddenly at ~38,000 miles it turned up looking darkish and smelling burned.