Been outa the game for about a year.

But a buddy of mine just got a 90 tsi awd.

Swapped out the ecu, and she starts, and idle's pretty good.

BUT, when you give it gas it revs up to 1500, drops to 1200 up to 1500 etc.

Back and forth for about 20 to 30 seconds then it revs up all the way.

Once you let it idle for 10 to 15 seconds does the same thing.

Any idea's to check? no check engine light.

Intake leak?

Yes, you could be looking at a leak.

Search for "Idle Surge" and you'll get the solution to your problem. The AAAQ and the Talon Digest (www.dsm.org) have this information.

it's not an idle surge though.

must've not explained right.

to start the car. it idle's at 750 to 800 all day long.

only starts to rev up and down when throttle is pressed.

When you let go of the throttle, does it still do that?

when you let go of the throttle it goes back to a normal idle.

i'm pretty sure it's just a major intake leak.

such as the stock side mount has corroded around the top as they always do.

find out soon.

but anything else I should look for?

sounds like a lower intercooler leak

Its the ECU, what year ECU did you put in? If its a 91-94 ecu in a 90' that is your problem. I know this because I have a 92 ECU in my FWD which has a 90' engine, just so I could start the car and move it (not driving it).

I believe there is some sort of rewiring you can do.

Not too sure what year the ecu came out of.

Have to do some diggin.

See what wiring is different and what needs to be moved around.

Have to check the inner cooler still too.

You have to switch 2 wires if you are using a 91+ ecu in a 90 there is a write up on it in the vfaq

I looked over the vfaq and couldn't find which two pins to switch...

if someone could give me a link it would be greatly appreciated.

thanks in advance.

Gavin

Pins 6 & 14.

http://www.vfaq.com/mods/ecu-harness-1G.html