Another TRAC light on problem - TM Engineering AWESOME!
03-26-03, 08:53 AM
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Another TRAC light on problem - TM Engineering AWESOME!
I have been having this problem for the past several months. Here are the symptoms:
1. intermittent throttle position hunting around when car is in idle w/ foot off gas pedal (I have an APEXI S-AFC installed so I can monitor the throttle position while this is happening. It will vary to sometimes 12-25% when it is idling and should be at 0%)
2. more prevalent in hot/humid conditions
3. as throttle position hunts, the engine starts to stumble at idle, the TRAC light (not TRAC OFF) eventually comes on and the engine sometimes stalls.
4. Restarting the engine clears the TRAC light, but will not fix the throttle position hunt problem.
Working with Todd M at TM Engineering, we deduced that it was the TPS sensor. Since they were the same, I swapped the primary TPS sensor w/ the one for the traction control TPS sensor. I noticed that the primary TPS sensor showed wear on the contact points. The traction control TPS sensor looked to have little wear, much less than the primaries which makes sense since the TRAC butterfly does not operate nearly as much as the main throttlebody butterfly.
I swapped the two TPS sensors and initially did not realize that the sensors had to be re-installed in such a way that the levers had to be loaded with the sensors. Well, the first time I just installed the TPS sensors without ensuring they were loaded and the car ran like crap. When you apply throttle, the S-AFC was reporting inaccurate throttle position. and the TRAC light came on and stalled the engine.
I disconnected the negative cable on the battery and re--installed the TPS sensors, this time with them properly loaded to the levers they attached to. Remember, I have swapped the more-worn primary TPS sensor with the less-worn secondary (trac).
Voila! the car runs great! The car is actually much more responsive, does not hunt throttle position, and idles great! One problem - the darn TRAC light is on. I tried disconnecting the battery cable over night and this morning the car started w/ the TRAC light still on.
I'll check codes later this afternoon, but does anyone know how to reset so the annoying TRAC light goes away? disconnecting the battery cable evidently did not do anything. However, the car runs great now!
Lastly, I need to tell you how pleased and impressed I am with Todd M at TM Engineering. I called him initially for help and advice and he ended up spending alot of time with me troubleshooting over the phone. I ended up ordering a new TPS sensor from him and got a great deal. Last night at 11pm when I go to install it, turns out it was the wrong one. I called his number planning to leave a v-mail for him to hopefully get first thing the next morning. To my surprise, Todd actually answered the phone and we talked at 11pm my time!!! We came up with the idea if swapping the TPS sensors as a temporary fix (I still want to replace my TPS sensor w/ new).
THANX TODD!
1. intermittent throttle position hunting around when car is in idle w/ foot off gas pedal (I have an APEXI S-AFC installed so I can monitor the throttle position while this is happening. It will vary to sometimes 12-25% when it is idling and should be at 0%)
2. more prevalent in hot/humid conditions
3. as throttle position hunts, the engine starts to stumble at idle, the TRAC light (not TRAC OFF) eventually comes on and the engine sometimes stalls.
4. Restarting the engine clears the TRAC light, but will not fix the throttle position hunt problem.
Working with Todd M at TM Engineering, we deduced that it was the TPS sensor. Since they were the same, I swapped the primary TPS sensor w/ the one for the traction control TPS sensor. I noticed that the primary TPS sensor showed wear on the contact points. The traction control TPS sensor looked to have little wear, much less than the primaries which makes sense since the TRAC butterfly does not operate nearly as much as the main throttlebody butterfly.
I swapped the two TPS sensors and initially did not realize that the sensors had to be re-installed in such a way that the levers had to be loaded with the sensors. Well, the first time I just installed the TPS sensors without ensuring they were loaded and the car ran like crap. When you apply throttle, the S-AFC was reporting inaccurate throttle position. and the TRAC light came on and stalled the engine.
I disconnected the negative cable on the battery and re--installed the TPS sensors, this time with them properly loaded to the levers they attached to. Remember, I have swapped the more-worn primary TPS sensor with the less-worn secondary (trac).
Voila! the car runs great! The car is actually much more responsive, does not hunt throttle position, and idles great! One problem - the darn TRAC light is on. I tried disconnecting the battery cable over night and this morning the car started w/ the TRAC light still on.
I'll check codes later this afternoon, but does anyone know how to reset so the annoying TRAC light goes away? disconnecting the battery cable evidently did not do anything. However, the car runs great now!
Lastly, I need to tell you how pleased and impressed I am with Todd M at TM Engineering. I called him initially for help and advice and he ended up spending alot of time with me troubleshooting over the phone. I ended up ordering a new TPS sensor from him and got a great deal. Last night at 11pm when I go to install it, turns out it was the wrong one. I called his number planning to leave a v-mail for him to hopefully get first thing the next morning. To my surprise, Todd actually answered the phone and we talked at 11pm my time!!! We came up with the idea if swapping the TPS sensors as a temporary fix (I still want to replace my TPS sensor w/ new).
THANX TODD!
Last edited by mdfdsc300; 03-26-03 at 08:58 AM.
03-26-03, 10:44 AM
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Therefore, the TRAC light wasnt fix right? Sometime the TRAC goes on due to the speed sensors problem. The SS are located by the tires. There are 4 speed sensors. One on each tire area. TPS will fix your idle problem, but not the TRAC light.
03-26-03, 10:51 AM
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thanx for the reply Lextreme,
My impression is that the TRAC light was directly associated with my TPS/idle problems. I believe it is staying on perhaps because I shifted the defective TPS sensor to the secondary trac one. I won't know for sure until I get another one that is certifiably functioning properly.
I don't believe there are any issues with my traction control system, speed sensors, etc. But that is the next logical place to go if the trac light still stays on after I replaced all my TPS sensors.
My impression is that the TRAC light was directly associated with my TPS/idle problems. I believe it is staying on perhaps because I shifted the defective TPS sensor to the secondary trac one. I won't know for sure until I get another one that is certifiably functioning properly.
I don't believe there are any issues with my traction control system, speed sensors, etc. But that is the next logical place to go if the trac light still stays on after I replaced all my TPS sensors.
03-26-03, 11:05 AM
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Its very strange. I have the same problem. My TRAC would come on after i run my car for few minutes or so. Anyway, I had a high idle problem and I took out my Deshpot. I thought it was the problem. Its was a trial and error type of repair.
The deshpot is located between the two TPS. The job of the Deshpot is to slow low the release of the accelerator. Anyway, after i take it out, the TRAC light goes away. After I detect why my car idle at 1600 rpm and i fixed and i reinstalled the deshpot. The TRAC light comes on again. It was off for about few months. Its very strange and i dont have an answer for that, but somehow for my case is deshpot related.
The deshpot is located between the two TPS. The job of the Deshpot is to slow low the release of the accelerator. Anyway, after i take it out, the TRAC light goes away. After I detect why my car idle at 1600 rpm and i fixed and i reinstalled the deshpot. The TRAC light comes on again. It was off for about few months. Its very strange and i dont have an answer for that, but somehow for my case is deshpot related.
03-26-03, 11:14 AM
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your high idle problem
Lex,
wow, 1600 rpm is very high for idle speed. Did you mess with the idle adjust screw at all? Also, did you mess with the TPS? I found that you can affect idle speed by rotating the position of the TPS. I did this on mine for a glass-smooth idle right around 680 rpm.
wow, 1600 rpm is very high for idle speed. Did you mess with the idle adjust screw at all? Also, did you mess with the TPS? I found that you can affect idle speed by rotating the position of the TPS. I did this on mine for a glass-smooth idle right around 680 rpm.
03-26-03, 11:25 AM
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It was the Idle Valve Sensor. The price was like $650 from the dealer, $300 used, but i got one for $200 installed. Yes, driving with 1600 rpm is not fun, wasting gas and wear out my torque converter. Its was a stop light nightmare. I also attached a picture of the IVS. Its the black round thing under the two blue vacuum lines.
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