TPS sensor, ASR, A/C and cam?
09-17-2006, 10:01 AM
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TPS sensor, ASR, A/C and cam? Does anyone know this full relation? My car sat for 4 months or so while it awaited a new clutch. Started it up and it had major hesitation (it was sitting with 1/8th of a tank). Made it to the gas station filled it up with 93. The hesitation is slowly fading away and now its almost non-existant. Now yesterday it gave me an SES light for tps senser perf. The light came on immediately after ASR kicked off and would not come back on (the a/c was on)
The exact code I got was this
P0121 Throttle/Petal Position Sensor/Switch A Circuit Range/Performance Problem
The whole point of this post is does anyone know the full relation between these 4 things is? Ive heard of a 5 volt reference getting drawn down and messing with the tps sensor and giving SES's. Is there any fix to this or is it just going to randomly keep kicking off asr (kind of a blessing in disguise) and triggering SES lights?
Appreciate any input from the tech
heres a link to OBDII codes if anyone needs them
OBDII codes
The exact code I got was this
P0121 Throttle/Petal Position Sensor/Switch A Circuit Range/Performance Problem
The whole point of this post is does anyone know the full relation between these 4 things is? Ive heard of a 5 volt reference getting drawn down and messing with the tps sensor and giving SES's. Is there any fix to this or is it just going to randomly keep kicking off asr (kind of a blessing in disguise) and triggering SES lights?
Appreciate any input from the tech
heres a link to OBDII codes if anyone needs them
OBDII codes
09-20-2006, 11:15 AM
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I'll throw you a bone here.
I chased this issue for a LONG time before I figured it out.
The cam changed your intake manifold vacuum at a given RPM, and as a result of the cam the engine is now seeing more air at a given RPM. The PCM interprets this as "well, the throttle position must be higher than what is being read by the TPS sensor because there's more air at this RPM than I'm expecting".
The traction control shuts itself off, the button will not work. You may throw a P0121 code. Replacing the TPS sensor will not help.
A/C changes the load on the engine and affects the airflow/vacuum reading even further.
The fix is in the tuning. Either open the MAP window range on the P0121 code, or raise the idle, or both. EFILive actually has a table where you can scale the expected airflow to correct the problem.
Hope this helps.
Rob (Bad30th)
I chased this issue for a LONG time before I figured it out.
The cam changed your intake manifold vacuum at a given RPM, and as a result of the cam the engine is now seeing more air at a given RPM. The PCM interprets this as "well, the throttle position must be higher than what is being read by the TPS sensor because there's more air at this RPM than I'm expecting".
The traction control shuts itself off, the button will not work. You may throw a P0121 code. Replacing the TPS sensor will not help.
A/C changes the load on the engine and affects the airflow/vacuum reading even further.
The fix is in the tuning. Either open the MAP window range on the P0121 code, or raise the idle, or both. EFILive actually has a table where you can scale the expected airflow to correct the problem.
Hope this helps.
Rob (Bad30th)
10-28-2006, 09:27 AM
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Haha, thread back from the dead.
Yes, it can hurt performance considerably, at least it did for me.
When it's in that state where the SES is thrown and the TCS is disabled, the car should be running in speed density (which can hurt performance if your tune/VE is off, sometimes the car will barely run at all), the light will be on on the dash but the TCS is still enabled in the PCM - although you can possibly spin the rear tires the PCM is still pulling timing and fuel.
My car ran like complete *** when that was going on. Hope that helps.
Rob (Bad30th)
Yes, it can hurt performance considerably, at least it did for me.
When it's in that state where the SES is thrown and the TCS is disabled, the car should be running in speed density (which can hurt performance if your tune/VE is off, sometimes the car will barely run at all), the light will be on on the dash but the TCS is still enabled in the PCM - although you can possibly spin the rear tires the PCM is still pulling timing and fuel.
My car ran like complete *** when that was going on. Hope that helps.
Rob (Bad30th)
03-28-2007, 05:54 PM
#7
and back from the dead again. i was doing a search on code p0121 and this came up. i just did an ls6 intake install. this could trigger this code? also, could something with the map sensor trigger this code as well or would the code be something else for the map sensor?
