Got a new AWD Talon today! Of course, PROBLEMS! Weird Idle and Vacuum Problem.

[joeym4130]

Got a 92 Tsi AWD today. Good thing it's not my daily driver.

All seems good except for this weird vac/idle problem, that only starts when warm.

Ok, so if you start the car cold, like I did this morning, it will idle steady steady ar around 900, and the vacuum reading is good on the boost gauge too.

But as it warms up... the idle goes to about 1200, and bounces between 1200-1500, and the vac gauge does the same, but it bounces around the 12-15 mark. And it stays like that until the next cold-start.

Any ideas on what changes after the warm up?


I also noticed:
On the cold start, when it is idling good w/ good vac, you can't rev the thing. If you quickly tap the gas the RPM's fall instead of rise, almost to the point of shutting down. This oddity goes away too, once the car warms up and has the idle problem.

Any clues?
Thanks!

 

[l3LacK Tsi]

check for vaccum leaks. pcv,brake booster hose,intercooler piping, etc. also check your tps,isc . do a search and see if anyone else had a simular problem. alot of idle threads to choose from good luck

 

[joeym4130]

Sigh, yeah I pressurized the intake, to 20psi, and no leaks unfortunately, because that would be too easy. Put in a spare ISC already yesterday too. Tps re-adjusted. seems like all the easy stuff.

But does anyone know why the vacuum only reads low, and the idle starts surging AFTER warm up? I never heard of this before..everything seems fine when the car's cold, minus the Rev problem cold.. weird.

 

[DSMLoverFromUA]

I have the same problem but i dont worry about it that bad. When cold ilds fine when its hot on the stop it goes up to like 1500 an more dont know why but i did a boost leak test and i dont have any, so any help would be apriciated.

 

[ddavisaf]

You hear your fan click on right? And the rpm's increase when the fan goes on, then decrease when the fan goes off. So, when it's warm and the fan is clicking on and off the rpm's increase and decrease accordingly. This different, or similar to your problem?