high idle problems sometimes

[talontsi2011]

ok i have 95 talon tsi awd in the morning it idles around 800 to 1000 rpm when it worms up it idles around 1500 to 1800 rpm also sometime it will idle up to around 2000 then drops to 1200 then back up to 2000 then drop again and just keeps doing it now if i give it a punch of gas it will stop and sit around 1500 again

 

[Brandon Mau]

You need to check all of your vacuum lines, perform a boost leak test. If all that is good then adjust your biss screw, I know I am missing something here could be a crappy maf sensor as well. I'm sure someone will have something to add to this I am sure I'm missing something just cant think of it at the moment

 

[98blackeclipse]

That happend to me one. I had a vac hose disconected and i didint have a power steering belt on. I put a new vac hose on and put the belt on and tada! It went from 1500rpm to 1000rpm

 

[talontsi2011]

ok ty but theres like 100 vac lines there what 1 do i look for

 

[Jafro]

A boost leak test will answer your vacuum problems if there are any. What you're describing is the same thing my car did when the ISC motor failed. I could blip the gas and it would settle down, but soon thereafter the idle would drift back up to 1000-ish. One burnt out coil in the ISC was all it took. There are 4 coils in it (2 di-pole coils). If you don't have any boost leaks or broken/missing vacuum lines, it's the next thing to check. Testing and replacement procedures are in this video if you want to rule it out...

YouTube - DSM ISC motor testing & Replacement

I have boost leak testing videos up there, too.

 

[oldman420]

Have you visited VFAQ Site - Visual Frequently Answered Questions yet and read the idle surge page in the intake section?
They also have great write ups on boost leak testing as well as some pretty good info on vac lines and possible throttle body leaks and so on....

Follow the diagnosis path and you will fix it.

 

[Jafro]

Just want to add something about idle surge. When that occurs, the car rhythmically revs and dies like clockwork every time it goes into idle. It's also usually triggered by an intake leak. You'll also find intake leaks with a boost leak test. That link is still a great read, but idle surge might not be related to what you're describing if the ECU isn't cutting spark like clockwork to bring the revs down.

 

[blessed1gst]

i had the same problem even if i screwed the biss in all the way it would stil idle high and i installed a 1g throttle body with the same isc motor and the same tps as before and it fixed it so i think it could be something within the tb like the fiav