P0121 is THROTTLE POSITION SENSOR 1 PERFORMANCE. Correct me if I'm wrong. .........................PaulOriginally Posted by foff667
P0121 is THROTTLE POSITION SENSOR 1 PERFORMANCE. Correct me if I'm wrong. .........................Paul
Yes. I think it is "position not as desired" or insufficient activity. But it seems to be fine when I log it and check it.
Hey, I just looked over the tune and there is a section "TPS Vs RPM limit Lower" and it is set for 1% @ 800 rpm, and some of my idle rpm values are actually a bit higher than that. It is mostly the P/N settings, and some on the colder ranges, but it does idle higher than that at times. My desired idle in gear at normal temps is set for 850.
Do you think this might be what is setting the code?
Last edited by mzoomora; May 29th, 2006 at 02:09 PM.
When this happened did it skip 2nd and 3rd, or did sequence thru them really quickly on the way to 4th...?
Last edited by joecar; May 29th, 2006 at 06:54 PM.
Okay. I tried something different today. I put it in D (3rd) and it shifted directly to third instead of fourth. While I was outside logging some stuff with it at idle it had a point where it was showing 2v on both the TPS and MAP at idle, and it was showing .4% for tps position for a long time also instead of just 0. This thing has me running in circles now. I had a trans shop check it out and they are saying it is not in the trans. The TPS is new also. Any help guys. Thanks.
That sounds like an electrical/grounding problem or a PCM problem; requires checking the TPS and MAP and their wiring using a DMM.
When you open the throttle smoothly, the TPS voltage or % should track smoothly.
With key-on-engine-off, MAP should read barometric pressure (close to 5V); with engine running, MAP should increase in response to throttle opening.
The TPS does react smoothly, from .7-4.5 volts. The map sensor reads 4.8 volts with the engine off I think, and read barometric pressure when off. The MAP does react when the throttle is opened.
I was wondering if the .4% (and sometimes .8%) for TPS is normal at idle?
I have a spare PCM I am trying to get flashed with a stock program to see how it reacts. I dont want to do it myself and waste a PCM lock on it and have it not be the problem. I checked the voltages at the wire ends with a multimeter and they looked fine, but it is an intermittent problem.
It high idles while cruising and doesnt go down until you come to a complete stop also. I tried everything in the P0121 troubleshooting tree and I am at the point where it reccomends the PCM be replaced.
Any other ideas or suggestions are appreciated.
Also, what grounds do you think would be the culprit? I will probably just have to go through them one at a time. All the ones I visually inspected looked fine though.
Okay, I was just out there now. I had it running in park and it was going back and forth between .4 and .8% throttle. I turned off the engine and let it sit and it started showing 1.8%, I unplugged the TPS and it went to 0, when I plugged it back it it went to 20% and stayed there. When i strted the car it was at high idle and wouldnt come down.
Is your throttle blade sticking open (rubbing against throttle body bore, weakened return spring, ...)...?
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