Hey all,

I've noticed recently that my cold starts will be really really lopey and rougher than normal. I also notice that 50% of the time, my Cobb AP will show my Air Intake Temp at 110-130 on cold start. Typically cold start temps are around 65 degrees and slowly work up from there.

Has anyone else experienced anything like this? Maybe a bad air temp sensor?

Thanks!

Doug

 

Sounds like a going maf sensor?

 

Ahh, good thought. Thank you.

 

IAT measured at the y pipe (boost pressure sensor)

 

I did not know that, thank you.

I'm not sure if this is normal, but I will drive the car for awhile and IAT is most of the time around 70-90 and everything is fine. I will park the car for 15 minutes or so at a starbucks or something, come out, fire up the car, and IAT is at 140.... If I even rev the motor in neutral I'll see knock. It will slowly back off from 140 down to low 100's but I don't see how IAT goes from 80 to 140 while sitting in a parking lot with the car off in 80 degree heat.

 

Heat soak.

And it is normal.

There is a 2nd fuse -- I forget its position -- associated with the engine compartment fan that when installed runs the engine compartment fan all the time the engine is on.

After the engine is shut off the usual/normal engine compartment fan behavior is unaffected.

You might consider installing that 2nd fuse -- if it is not already installed -- so see if this reduces the severity of the heat soak. It can't eliminate it.

And you might still have to be easy on the engine until it has run enough, the fan has run enough, to cool the intake to the point the intake air temperature is back to near normal.

While a heat soak with a corresponding rise in intake air temperature doesn't affect stock engines but does your engine this could be due to the tune. It could be the tune has just made the engine more sensitive to intake air temperature and thus heat soak.

 

Macster, thank you so much for that detailed reply. That puts me at ease for sure knowing it's just basic heat soak. Much appreciated.

 

Correct is at the ypipe but controlled by the maf sensor on wire 2.

 

Motronic read IAT after the intercoolers...at the y pipe...the temperature sensor is integrated at the boost sensor... if your car is shut off, the y pipe temp goes near the motor temperature....takes a little time to cool it down. It makes no sence to measure the IAT before the intercoolers at the MAF

so if you parking your car with hot engine, it is normal that the IAT is near Engine compartment temperature..check both it is near the same at this time

 

That is correct but heres the other wire for the iat.

 

FWIW, starting the car after having parked it for 15mins is NOT a "cold start", it's a hot start and none of the warm up protocols will be used.

 

the integration of a temp sensor inside the maf is used for the function of the maf himself...(not for IAT)