Surging Problem... $100 reward to who fixes it!

[shadywang]

Ok. Here’s the deal. I just finished building a 93 TSI AWD from the ground up. I’m rather knowledgeable with cars, it’s my 3rd DSM, but I just can’t figure out why it’s surging at Idle from about 800 to 1400. Here’s what it has:

6 Bolt
16G/FMIC
MAFT 2.01 w/3" MAS
AFC-1

Here’s what I have fixed or made sure it wasn’t the problem:

It has a Good:

ISC
BISS
TPS
CAS

There is no check engine light. There are no vacuum leaks. Checked 2 times. Checked all wiring for AFC and for MAFT, its all good. I removed the maft, went back to stock air setup, still does it. I removed the AFC completely, still does it. I have a good O2. Any help would be great. If you give me the tip that fixes it, I will paypal or mail u $100. Not a problem. Thanks for looking and PLEASE HELP!!! feel free to email me at [email protected] with any ideas or if you need more information to try and identify the problem....

Thanks

Ron

 

[Seraphix]

In the brake booster hose is a check valve, make sure when you "build it from the ground up" that you didn't forget to save that valve. it's the lump in the stock hose, just cut it out and slide it in the new hose. it shouldn't be able to blow into the booster, just back into the manifold. i had an idle surge exactly like that for that reason. replaced the valve, and idle is a perfect 750. [email protected] for paypal. =P

 

[4g63mightymax]

I have a spare 91 awd turbo ECU and no matter what car I plug it into, it runs for a few seconds normal and smooth, then it starts surging the engine and wont stop. I called a ecu rebuild company and they told me that some part inside the 91-94 ECU's malfunctions occasionally and causes this to happen. However, it is Not the caps. I dont know how true this is, but I know my magic 91 ECU (with new caps by the way) is proof that it can happen. The same ECU rebuild company told me that it isnt logical (money wise) to fix these ECU's when they do this, so your better off finding one that works correctly and hope it doesnt happen to your new one. So my vote, is try a different known working ECU and I think you will find your problem.
(by the way if anybody has any more info on this, feel free to educate me further)
Jeremy

 

[kalla]

Please check the ISC coils with a multimeter per service manual .. there are four coils and if even one of them is bad, the idle will hunt all over the place .. happened to me.

 

[jott5555]

so have you fixed it or whats the deal? im interested in my 100 bucks..

 

[blue92laser]

Did you try resetting your ECU? Sometimes, it really does help for it to learn any new fuel curves or ignition timing sets. Unplug the battery for 15-20 seconds, and try starting it up again.

 

[libbert2]

do you have the collent hoses hooked up to the throttle body? if not the throttle body does not know when the car is warmed up so it surges, dont know why. I dont have mine hooked up and it does this when it gets cold.

 

[beat90tsi]

try lowering your idle with the BISS screw....as low as it will go