When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
OK, so the air fuel sensors seem good to me, and they are expensive to replace, so before I do that, what would I need to get the air fuel ratio to 14.7 from 14.1? Is this even something that can be changed electronically or manually? Or is it determined by the computer and can't be changed? In other words, is my 14.1 ratio something that is off and can be directly, or is it just a symptom of something else that is wrong in my car that is throwing the air fuel mixture off (such as blown head gasket, coolant/oil leak into combustion, vacuum leak, etc.) and once that is fixed, the computer will automatically set the air fuel ratio to 14.7 without any intervention? I am guessing it is the latter, as it would make sense that a vacuum leak would throw the air fuel ratio off.
All the videos I have seen on youtube tell you how to adjust screws, springs, wheels on carburetors or air flow meters to get the desired air fuel ratio, and they say doing so usually only adjusts the ratio at idle and not throughout all range of RPMs, so it doesn't seem like it is applicable to an electronic throttle body, but I am no expert in this area. Plus, it might not actually fix my problem as the air fuel ratio might just be indicative of some underlying problem and tweaking it is only addressing the symptom and not the disease.
Also, I am starting to think that as Audiqv8 said, it might be that cleaning the throttle body may mess with the sensitive electronics and sensors. I read that cleaning the throttle body in electronic systems should be done by mechanics, so I might have damaged it when I cleaned it. I saw a repair manual scanned page on the forum a while back on how to recalibrate the throttle body by tightening the screw so that the sensor reads 14.7, unless I also messed with the sensor and even that reading is wrong. Right now, Torque Pro says my throttle body is at 14.9 at idle. Is it worth it to try to manually recalibrate or replace throttle position sensor? See image below (which is not for a 2009 RX 350, unfortunately; I would need to get the repair manual to do this right). Before I do this, can someone, if they get a chance, tell me what the throttle valve opening percentage is at idle and what their vacuum is at idle. Torque Pro says mine are 14.9% and 25.7 in Hg so I want to compare if that is normal before I attempt anything.
Audiqv, the screenshots still gave me useful information. Thanks.
I would still like to know what the idle throttle percentage, the idle vacuum, and the air fuel ratio are for the RX 350 if anyone can check on their vehicle. I am going to use the upcoming time off to work on the car so that information would be greatly appreciated. I tried checking in the Haynes repair manual, but it had nothing specific on these topics.
I studied my Torque Pro output a little bit more carefully. This is what I found. Upon startup, the RPM is at 1500 and slowly drops to 640ish as the engine warms, taking about 10+ mins to do so.
The throttle percentage starts at 18%ish and slowly drops to 14.9% as the engine warms. Audiqv, is 16.9% your startup throttle percentage, or does it start higher and then drop to 16.9%? Does it continue to drop if the engine is left idling, and if so, how low does it go?
The air fuel ratio stays at 14.1, which I believe is too rich, but again I don't know where the RX 350 is supposed to be when working properly. I read online that rich air fuel ratio could be due to leaky fuel injectors and could be causing my low mpg, so I might try to look into that. I did naively use give bottles of Techron fuel injector cleaner consecutively (one after each fillip five times in a row), and maybe that destroyed my fuel injectors or some other component and is responsible for the rich condition of the AFR. What else could be causing my rich AFR? How would I try to fix it?
The vacuum as I said is around 25ish, and most cars have 18-22 vacuum, but maybe having a high vacuum isn't bad. It does't seem like a high vacuum could hurt.
At idle, the LTFT1,2 start out at 3ish at idle, and then slowly drop to 0 as the engine warms up, but then as the engine warms up even more they go back to 2ish. When I hold the RPMs at a steady 2500, the LTFT1,2 become -2ish. Does going from lean to rich mean my car has a vacuum leak, or is this within normal operating parameters? At idle, the STFT1,2 start at -3ish and then go to 0 as the engine warms up, but then as the engine warms up even more, they go to 1.5ish. When I raise the RPM to 2500, STFT1,2 vary from -3ish to 2ish. What could these mean? Do they imply there is a problem, or are they within the normal operating window?
That's pretty much all I have gotten from the Torque Pro scanner.
3.5 has a timing chain, 3.3 has a timing belt, so that seems like a pretty big difference to start with internally at least. May be that the drive (serpentine) belts are different as well, think 3.3 may have 2 of them, 3.5 only one.
dont these 2 engines have pretty much the same parts etc; with the only difference being one is a 3.5 and the other is a 3.3?
Nope the RX350 3.5 engine is totally different. It uses a timing chain and not a belt. It was redesigned by Toyota unlike the RX330 which used and upgraded RX300 engine. Both RX330 and RX300 used timing belt.
3.5 has a timing chain, 3.3 has a timing belt, so that seems like a pretty big difference to start with internally at least. May be that the drive (serpentine) belts are different as well, think 3.3 may have 2 of them, 3.5 only one.
The RX330 have two external belts. One is used for the Alternator and AC compressor and the other is used for the ps pump. The RX350 have one serpentine belt which is also used to run the water pump where the RX330 water pump is run off the timing belt.
Nope the RX350 3.5 engine is totally different. It uses a timing chain and not a belt. It was redesigned by Toyota unlike the RX330 which used and upgraded RX300 engine. Both RX330 and RX300 used timing belt.
well glad i have a chain rather than belt because i know those timing belts arent cheap to replace whereas I dont think the chains have to replaced or do they and if they do after what mileage?
At the risk of being annoying and repeating myself, having already asked for this information once, can someone who has an RX 350 (2009ish) please tell me what the air fuel ratio, throttle percentage, and vacuum read at idle (not on startup, but at idle after engine has warmed up; the throttle percentage for me starts at 16.9% at startup and falls to 14.9% after warm up at idle). I need to know these to diagnose my car. I checked for a head gasket leak using a coolant pressure tester and a combustion block tester and found no leak. But I still get lower mpg than I should and grey smoke from exhaust at startup which turns into white smoke after driving a little and then altogether disappears after driving about 2 miles. The exhaust smoke smells like unburnt fuel. So this unburnt fuel is probably being wasted which may be why I get low mpg. This seems to agree with the fact that my air fuel ratio at idle is 14.1, lower than Audiqv8's 14.7 (though he has an RX330 so the comparison might not be fair). It also seems to agree with the fact that my idling throttle percentage after warm up is 14.9 vs. Audiqv8's 16.9. Knowing what the correct values are would be extremely useful to me. I don't want to replace MAF, Throttle Position, Air Fuel Ratio, and oxygen sensors, and recheck the spark plugs, check for vacuum leaks, and replace the fuel injectors to fix the rich air fuel ratio and grey smoke from exhaust problems if those aren't really the problems. So again, if someone has access to this information or can easily get it with the torque app, I would greatly appreciate it.
Here is my car at startup
Since you have Torque Pro you can go to a used car lot and see if they will allow you to hook up the dongle on a car similar to yours.
12-17-18, 04:13 PM
