Bad Throttle Position Sensor, Again?? [Archive] - GrandAmGT.com Forum

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AleroB888
02-25-2007, 10:18 PM
I am posting this here because I think it might be related to the extra heat produced by the SC, headers, and stress of hard performance use:

I have replaced my throttle position sensor 4 times in three years, and twice the complaint was the "jumpy idle" most commonly seen. The first occurrence had some bizarre symptoms, though:
1) Gas gauge reads Empty
2) Transmission bangs shifts like it had full line pressure
3) No SES light but threw code indicating problem with 5 volt line
4) After about a week, the more typical erratic idle showed up.

But today, I had yet a new symptom. I was doing some WOT tests, and the car acted like the throttle was stuck open. This happened once yesterday, and again today, out of about 10 WOT passes. Each time I was able to pump the gas pedal frantically and restore correct operation. I didn't find anything mechanically wrong with the linkage or TB, so I replaced the TPS. I am not sure that that's the problem, of course. But how the hell do I find out for sure?

lone_wolf025
02-26-2007, 10:37 AM
Check the sensor with a voltmeter. I dunno what the specs are supposed to be off hand but mess with the throttle while watching the readout and see what happens.

AaronGTR
02-26-2007, 11:35 AM
Well, the sensor wouldn't get the throttle open, so if it stayed at WOT, there obviously is a mechanical problem of some kind. It might not seem like it, but the throttle can stick when the engine is hot and working with the cable and you might not see it otherwise.

Take the TB off and clean it. Check the plate by hand. Look for any marks on the inside where the plate might rub when fully open. You might need to do some hand sanding if you find any rough spots. You might need to adjust the throttle stop too and do a throttle position learn procedure.