Random "Check Engine" solved
07-19-04, 05:12 PM
#1
Lexus Champion
Thread Starter
Random "Check Engine" solved
So, a few of you know about the issues plaguing my brother 's (Link 13) first-gen GS. I guess "plague" is a bit strong here, as the car has never left him stranded- it was more of a nuisance than a problem.
His car would occasionally flash the "Check Engine" light, usually when the engine was relatively 'cold' or sometimes when decellerating. If the Check Engine light occurred at idle, it was accompanied my a stumble and then a slight lurch (since the car was typically in Drive) as the computer tried to make the car idle properly (my brother will probably chime in and can be more specific about how the problem manifested itself).
I did the usual checks- PCV valve, EGR, plugs, cap rotor- the only thing I found was a dirty air filter (replaced it, did not help). Thanks to a search on CL, my brother found the instructions for an engine diagnostic. We performed this, and it resulted in "41" TPS Sensor (Throttle Position Sensor). In another thread on CL, we found the TPS troubleshooting instructions. I tested the TPS with my multimeter and sure enough, it appeared to be dead.
Per my findings and recommendation, my brother called the local Lexus dealer last week and ordered a new TPS. Since he was out of town last weekend, I picked it up Saturday and installed it yesterday. Problem solved!!
The car is now quite a bit more responsive, especially at smaller throttle openings: the exhaust also smells "cleaner" (not rich like before), it idles perfectly, and I suspect it will have better fuel economy (time will tell). The transmission even responds more quickly- a note: it is important that the TPS is calibrated properly- fiddling with it will only cause a massive 'clunk' when the car is shifted from Park or Neutral into Drive. The instructions we found online detail how to perform this calibration, and it worked perfectly.
I have a number of theories for the symptoms: I believe the transmission needs to know how wide the throttle is open to make appropriate decisions, and because the TPS took a dirt nap the computer runs the engine in a 'fail safe' or 'limp home' mode at idle and low throttle openings. From what I understand about the older Toyota/Lexus computers, the Oxygen sensor feedback helps the computer decide about idle and low-rpm operation, and at higher-rpm the car runs in 'closed loop' mode, essentially running off of a predetermined program and ignoring sensor input. Basically, the computer didn't know what was going on at low rpm, and it was running in limp home mode in this rpm range.
If your GS has about 100K miles and has symptoms like I mentioned above, check the TPS.
Hope this has been helpful...
Best regards,
Bob
His car would occasionally flash the "Check Engine" light, usually when the engine was relatively 'cold' or sometimes when decellerating. If the Check Engine light occurred at idle, it was accompanied my a stumble and then a slight lurch (since the car was typically in Drive) as the computer tried to make the car idle properly (my brother will probably chime in and can be more specific about how the problem manifested itself).
I did the usual checks- PCV valve, EGR, plugs, cap rotor- the only thing I found was a dirty air filter (replaced it, did not help). Thanks to a search on CL, my brother found the instructions for an engine diagnostic. We performed this, and it resulted in "41" TPS Sensor (Throttle Position Sensor). In another thread on CL, we found the TPS troubleshooting instructions. I tested the TPS with my multimeter and sure enough, it appeared to be dead.
Per my findings and recommendation, my brother called the local Lexus dealer last week and ordered a new TPS. Since he was out of town last weekend, I picked it up Saturday and installed it yesterday. Problem solved!!
The car is now quite a bit more responsive, especially at smaller throttle openings: the exhaust also smells "cleaner" (not rich like before), it idles perfectly, and I suspect it will have better fuel economy (time will tell). The transmission even responds more quickly- a note: it is important that the TPS is calibrated properly- fiddling with it will only cause a massive 'clunk' when the car is shifted from Park or Neutral into Drive. The instructions we found online detail how to perform this calibration, and it worked perfectly.
I have a number of theories for the symptoms: I believe the transmission needs to know how wide the throttle is open to make appropriate decisions, and because the TPS took a dirt nap the computer runs the engine in a 'fail safe' or 'limp home' mode at idle and low throttle openings. From what I understand about the older Toyota/Lexus computers, the Oxygen sensor feedback helps the computer decide about idle and low-rpm operation, and at higher-rpm the car runs in 'closed loop' mode, essentially running off of a predetermined program and ignoring sensor input. Basically, the computer didn't know what was going on at low rpm, and it was running in limp home mode in this rpm range.
If your GS has about 100K miles and has symptoms like I mentioned above, check the TPS.
Hope this has been helpful...
Best regards,
Bob
Last edited by SoCalSC4; 07-19-04 at 05:14 PM.
07-20-04, 11:02 AM
#6
interesting info... thanks for bringing it up. I have to take my car in for diagnostics next week also I have been sufering with a bad fuel economy problem and my exhaust smells really rich also... I'll let you guys know what I find out.. Also did you guys do the engine diagnostics yourselfs?
07-21-04, 11:14 AM
#7
Well today I had my car diagnosed and it threw up a code 41, TPS..So I can replace it myself but I need to know how to calibrate it..if anybody has some instuctions on how to do it please post it up..I also want to add that my car wasn't showing a Check engine light, but my car had all the symptoms..So, if your car is acting like this and there is no CEL you may want to have it diagnosed..
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07-23-04, 07:40 AM
#8
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Nice find, can someone copy/paste up the instructions to pull up the diagnotic codes. i'm in New York right now on dial up so its really slow. i just want to read up on it so when i get back i can work on my car.
also how much was the TPS sensor and how hard was it to change?
also how much was the TPS sensor and how hard was it to change?
07-23-04, 12:25 PM
#9
Originally posted by Jmai22
Nice find, can someone copy/paste up the instructions to pull up the diagnotic codes. i'm in New York right now on dial up so its really slow. i just want to read up on it so when i get back i can work on my car.
also how much was the TPS sensor and how hard was it to change?
Nice find, can someone copy/paste up the instructions to pull up the diagnotic codes. i'm in New York right now on dial up so its really slow. i just want to read up on it so when i get back i can work on my car.
also how much was the TPS sensor and how hard was it to change?
The TPS sensor is easy to change, but the calibraton is very difficult and I am still having a problem and I wish someone would chime in on how to calibrate it..I have the mechanics repair manual and I am following the directions but I can't seem to get it right..I paid $95 for the sensor from lexus, but I am really irratated about the calibration..If anybody has a suggestion on how to calibrate it please let me know, because I'm going nuts overhere...
07-23-04, 01:34 PM
#10
Lead Lap
Johnee, I found instructions for doing this on the following thread:
https://www.clublexus.com/forums/sho...=calibrate+TPS
My brother did it on my car, so I will ask him if you are still having issues with it.
https://www.clublexus.com/forums/sho...=calibrate+TPS
My brother did it on my car, so I will ask him if you are still having issues with it.
07-23-04, 02:46 PM
#13
Originally posted by link13
Johnee, I will ask him this weekend and let you know. He might see this thread and chime in beforehand too.
Johnee, I will ask him this weekend and let you know. He might see this thread and chime in beforehand too.
07-26-04, 06:36 PM
#14
Lead Lap
Johnee, I talked to my brother and he followed the general instructions for adjusting the TPS that are in the thread I posted earlier. He did not have any issues in doing so. He suggested that the repair manual for the 93-97 GS300 may have some details specific to the 2JZ-E. Otherwise, you might have something else going on with your car from what you described.
07-28-04, 07:53 AM
#15
Originally posted by link13
Johnee, I talked to my brother and he followed the general instructions for adjusting the TPS that are in the thread I posted earlier. He did not have any issues in doing so. He suggested that the repair manual for the 93-97 GS300 may have some details specific to the 2JZ-E. Otherwise, you might have something else going on with your car from what you described.
Johnee, I talked to my brother and he followed the general instructions for adjusting the TPS that are in the thread I posted earlier. He did not have any issues in doing so. He suggested that the repair manual for the 93-97 GS300 may have some details specific to the 2JZ-E. Otherwise, you might have something else going on with your car from what you described.
Link13-Thanks for your help..I finally figured it out!!! I went out and bought a vaccum gauge and was able to adjust it perfectly..Thanks and now my car is running great and it doesn't smell like gas when I turn the car on..It seems more responsive also..Thanks again..
Last edited by johnee78; 07-28-04 at 07:55 AM.