Yeah another idle problem...

[Seebo]

Hi everybody, new DSM owner here! I have a 92 AWD tsi with.... wait for it..... an idle problem. Please hear me out though. I had searched probably 25 different threads on idle issues on this forum alone but none of them sound like mine (same mindset as everyone else ) Now I am mechanically inclined and I used to play around with old turbo k cars but I'm unfamiliar with the DSM world and it's seemingly endless array of proprietary controls that can affect idle. BISS, FIAV, their reduculously expensive TPS and IAC. So I do know the car has a slightly faster than acceptable boost leak and and exhaust leak, it has a FMIC, stock turbo, cheap BOV, Walbro 255. She starts but whether ice cold or warmed up she will fluctuate between 700rpm to 1400rpm within a few seconds and repeat (unless it stalls). I have watched a few "idle surge" videos and mine seems so much more severe than some of the others. I also have a dead spot in the throttle that starts at idle and picks up around 1800rpm (assuming a bad TPS) I have not begun any real diagnosis and I'm not looking for a straight answer just wondering if anybody has experienced an idle surge that exaggerated. If so where did you start and where did you end up?
Thanks!

 

[barza21]

Hello,

The idle problem that I had was pretty bad, almost like the one you described. Fix the leaks. Even though small, they still can cause a problem. Make sure you're checking all the possible points of leaking: Every coupler, Every piece that has a gasket, etc. Also, check that the tps iS adjusted correctly. Check the condition of the iac motor as well. Lastly, if you feel like being a bit more thorough, you can check the iac drivers in the ecu. Make sure that they are not burned. The issue that I had was resolved by blocking off my fiav. I did the free fiav mod and haven't had an issue since other than my ecu iac drivers being damaged due to the capacitors leaking. I created a thread dedicated to my issue and I shared my soulution. Look it up. Hope it helps you with your journey.

Good luck.

Oscar

 

[me2151]

What you describe is major leaks(boost/vacuum)look for any disconnected hoses or blank nipples.

 

[Seebo]

Well guys and gals I took a little video and did find a significant exhaust leak. I also found several connectors not connected to anything. I'm going to order a new manifold and j pipe (mine is an atrocity). One of my coolant temp sensors (upper one) is missing it's connector. Also I noticed what I'm assuming to be my intake air temperature sensor is missing it's harness connector too. Anyway I'm gonna start tearing into this beast tonight and I'll be checking everything I've had suggested to me which I'm very greatful for. Here is the YouTube Url to those interested in the idle surge.

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[bradcurtis15]

Sounds like a very bad boost/vacume leak. look up how to test for boost leaks and look up how to make a boost leak tester. fix the leaks first.

 

[pauleyman]

That is no different than any dsm idle surge. Fix the leaks. Fix coolant temp. You assume intake air??? Where?
You just stated you have known problems. You need to fix all of those problems until you do any diagnosis

The exhaust leak shouldn't be a big deal concerning idle surge but intake leaks and throttle body leaks will be bad.