Cannot Idle at All

[andyhug]

Has anyone ever experienced a problem with a 1g (or 2g) where the only way to keep the car running was to repeatedly and continuously modulate the throttle?

I've had this problem intermittently for the past two years. The car is a '92 tsi awd 7 bolt with a big 16g, 550s, walbro fuel pump, afpr, full 3" turbo back, and an HKS VPC with about 130k on the odometer. It is not a daily driver.

Again the problem I'm having is that the majority of the time when I start my talon it will rev up to about 2000 rpm then fall back down to 500 or so and die out. The only way to keep the car running is to open the throttle a good amount (or all the way) over and over resulting in revs going up and down about 500 rpm. This 500 rpm range of variance can be kept lower in the rpm band with less frequent modulation and higher with more frequent modulation. Sometimes the car will start up and run fine but that seems to be becoming less frequent. I have no idea what is going on and am hoping that from the description of the symptom someone may know what this is. Any useful input or thoughts greatly appreciated.

 

[Lofty]

This would be Idle Surge.
Your ISC is bad.
Look it up on Vfaq.com

 

[andyhug]

Idle surge can be so bad that there is no way to hold the engine at a steady rpm no matter what you're doing with the throttle?

 

[r1991_4g63t]

Idle surge can be so bad that there is no way to hold the engine at a steady rpm no matter what you're doing with the throttle?

 

[andyhug]

If it is the ISC motor would it act the same when it is unplugged? And when I say I can't hold a steady rpm, I mean holding the throttle halfway or wide open results in the car barely running at ~500 rpm.

 

[talon187]

yes it will act the same or worse with the isc unit unpluged. eaither get a new isc unit or get a diffrent thorttle body that doesnt require one. or try blocking it off theres some people who have blocked it off and have there car run ok at idel. me personally i dont have an isc. i have bbk 75 mm throttle body and a custom intake manifold. car idels pretty good not totally steady surges between 200-300 rpms. not bad at all. when i had surge mine would go to 2.2k down to 800 and back up again