I took my 99 GST to my work to get scanned for codes and it was something about a malfunctioning TPS (Code 0510). Before I was able to replace it I had to get it smogged because of a ticket. I barely failed because of slightly higher HC's and NOx in the 15 mph test. I was told the car was fine but I need to figure out why it failed that small little part. I told the smogger that I had my light come on and it was because of a faulty TPS and I believed that was the problem because the sensor was probably giving false readings.

He agreed saying its a very high possibility because the sensor could be telling the ECU more air is entering the Throttle Body than there actually is. Therefore, more fuel is probably being added to compensate when its not supposed to. I did notice my gas mileage was lower than normal, im pretty sure im not just paranoid. I immediately bought the replacement OEM TPS after I received my results but havent had the time to install it yet.

Sorry for the long post, but I was just looking for a third opinion on my situation. As far as my knowledge goes...there is nothing else mechanically wrong with the car. Thanks.

 

without the tps doesn't the ecu revert to a stored fuel map which is not very good since u loose out on gas milage. I tried driving 1 hole tank without my tps connected and the car would idle higher and run more rich and in the end cost me more in fuel. But that expirement told me the car was functional and i had no random missfire since the ecu could no longer look for it with the tps not there.

 

That sounds like whats happening to me. So I was right about the gas mileage, its just not that poor since its just malfunctioning...not missing. And when I turn on the window defroster my idle will rise to 1k-1.2k RPM. And the assumed extra fuel being added to create a richer mixture would raise the emissions lvl's. Its starting to sound more like whats causing the problems I have. Thanks Nubie

 

yea that should fix your problem, just make sure you drive your acr around a bit before bringing it for the test to clean it out.

 

Thanks, that shouldnt be a problem...my next test date is like 3 weeks from now due to massive emissions tickets i guess. The smog tech said they were still on their back log trying to catch up on all the smog tests they need to do. I swear those cops must be car modification happy or something. At least I know that new TPS wasnt wasted money, thanks again.