I adjusted my TPS the other weekend. I drove the car around fine for a few days then one morning it wouldn't rev over 1500. I got out, popped the hood, and found out that I forgot to plug the TPS back in after adjusting it (go me...). I plugged it in and was good to go.

So here's my question: why would the car run fine for a few days then not go over 1500 the next?

The only thing that changed was the weather. On the day it didn't work it was probably about 10 deg. warmer. I don't have any emissions equipment (no thermowax either) so nothing would be affecting my idle otherwise.

Would an air temperature sensor (or something) affect things?

 

the CEL didn't come on with the plug off?

 

S4, no CEL

 

maybe it unplugged after driving those couplr of days.

 

Kinda doubt it. The damn things hard enough to unplug on its own.

 

I might try with / without TPS plugged in just to make sure. I'm pretty sure the ECU fail-safes the TPS to either WOT or idle. If it's WOT, I imagine the engine would idle pretty badly, and if it's idle, anything but idle might have issues (possibly like you're seeing).

The IAT sensor in the AFM could have a bearing there (I believe it's used to determine incoming air mass), but somehow I don't think 10 degrees would change things that much!

 

The idle was pretty normal. It's just when I gave it gas it wouldn't go past around 1700 rpm. It'd hit 1500rpm and sputter to dead within 200rpm. It sounded like my engine stalled until it came back to under 1500rpm and did the same thing again. If I let off the gas it did its normal (crappy) idle.