<cross posted from Passat forum, sorry Deakins
)
I have a '92 Passat, with teh 9A 2.0 16V engine, CIS-E Motronic...
Yesterday I made an attempt at replacing the head gasket, until I realized I wasn't going to be able to get the lower radiator hose off without cutting the hose clamp, and I didn't have a replacement. I got off the intake manifold, ignition system, fuel injectors and lines, and the intake boots between the throttle body and fuel metering unit.
I put it all back together again and fire it up, and it runs awful. It holds a rough idle at around 900rpm, and I can smell that it's running really rich. I thought maybe the cold start injector was staying on, so I disconnected that, but it still ran rich.
I suspected the ignition system, so I took it out for a road test, and it pulled hard all the way to 7000rpm, so I don't think the ignition system is at fault. The engine has very recent Bosch platinums, a very recent distributor cap, etc...
The only thing I can really think of is that there is an air leak somewhere, and that the Motronic is trying to compensate by adding more fuel to compensate...
Any ideas?