Need help diagnosing my brothers problem.
11-03-2005, 10:18 PM
#1
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Need help diagnosing my brothers problem. He is having a downshifting problem. Sometimes when he takes off slow and the car upshift to 2nd gear around 20mph and then when he floors the car it absolutely will not downshift. I've tried lifting the throttle then stomping it to the floor again and it still doesn't down shift. The ses light came on and I checked it with my code reader and it was a tps code. I thought that was simple. Well we've replaced the tps sensor and there is still no change in the car. We've also checked the voltage to the tps sensor with a multi-meter following the instructions from a chilton's manual. I'm reading the right amount of referance voltage and I'm also getting the right amount of votage when the throttle is increase at a gradual rate. I'm baffled. Can anyone here possibly shed some light on this for me?
11-03-2005, 10:42 PM
#3
It is his tuning. It is short shifting because of his TPS being out of range. He'll need to adjust his map values for P0121. Look and see what his map value is sitting at idle in park and in gear. Make sure the parameters for that code are beyond that. I'd suggest setting them to 45 and 75.
if its cammed the cam changed the idle vacuum (which is your map value). So you need to adjust that table. And since the TPS has been replaced i dont see what else it could be, unless im misunderstanding the problem
if its cammed the cam changed the idle vacuum (which is your map value). So you need to adjust that table. And since the TPS has been replaced i dont see what else it could be, unless im misunderstanding the problem
Last edited by 98NBM_TransAm; 11-03-2005 at 10:48 PM.