Old Library

(This is cross-posted to the Vortex)

Last night I had the battery disconnected for a while to
reinstall an amp. After finishing and getting everything
back together, I started the engine and everything was
fine. This morning however ... different story. The idle
started bouncing between about 400 and 800 RPM as soon as
I got backed out of the driveway. This condition kept up
all the way to work, except that every now and then it
would bounce all the way to about 1000 and when it did
that it'd settle back to 700 and idle perfectly. As soon
as I gave it some gas and let the revs drop it would start
bouncing again. When I got to work I started and stopped
the engine a couple of times, but it idled the same. No
CEL.

Could this have had something to do with the battery being
disconnected? I've had it disconnected before for whatever
reason and it's not caused this behavior. Does the car
have to learn how to idle or something?

Car:
98 GTI VR6, 58863 miles, 1/2 tank gas BP 93, new Bosch
plugs at 30K

Relevant Mods:
GIAC chip at 24K, K&N drop-in at 6K cleaned at 50K

Any ideas greatly appreciated!


matt.

Actually, I think what you want to do is the following (works for Mk4's, but not sure if it's the same for Mk3's):

1) Disconnect the battery and let sit for a few minutes.
2) Reconnect battery and turn on the ignition -- but DO NOT start the engine.
3) Let that go thru the motions of the throttle body adaptation.  Immediately after turning on the ignition, you'll hear the TB moving around and learning the positions.
4) After a few minutes, go ahead and start the engine and let it idle for a few more minutes.
5) Drive around and eventually all the readiness codes will have passed or cleared.  You'll proably need a VAG-COM to clear the intermittent power failure DTC that you get when disconnecting either the battery or the ECU.

-Jason