99 Jetta Idling Crappy

I've got an intermittent issue with my 99 Jetta. It drives fine, but idling, it pulses from ~800RPM to ~500RPM (and sometime stalls). It doesn't happen all the time, but seems to happen more often when the engine is cold or there's an electrical load (headlights, loud stereo, power windows, etc). I've done a tune-up (oil w/ filter, top off fluids, spark plugs, wires, and distributer cap). I went to AutoZoo and PepNuts, and they suggested a bad ground or alternator/battery fault. I had them run a free check on the battery/alternator which turned up fine, but I replaced the alternator and drive belts anyway because I'm stubborn. Needless to say, it's still idling like poo and I don't know what to try next. Any ideas? :) -Dan

I'd also check all vacuum lines and connectors for cracks and leaks.

When you check the throttle body, check the hose that goes from the TB to the MAF. If there is a crack in that hose, it will let in extra air and this will result in a crappy idle or no idle if you come to a stop after driving. IOW, the engine will die. This happened to me and was just a TB hose replacement.

It's a 2.0L GL and I've got Bosch 4+ plugs. I had the ECM scanned a while ago because of an intermittent check engine light and I think it gave a few errors about misfiring on multiple cylinders, which is why I replaced the plugs wires and cap. I'll check on the ignition coil and throttle body and get back to ya. Thanks!

On Jan 13, 1:00 am, "dave AKA vwdoc1" wrote: > BTW you did not mention which engine you have in this Jetta! > I will assume you have a 2.0l but I don't know. >

If your engine has a distributor then your sparks plugs should be something like F8RS or FR8S. What plugs did you pull out?

Agreed. The Bosch 4-prong plugs I've heard no good about. Don't have to go dealer exactly but at least get the dealer-equivalent at your local FLAPS.

See my reply (Message-ID: ) to Duwaynea Anderson in the thread "Anything the prophet might do, to deprive himself of your sustaining vote?"

cold or there's an electrical load (headlights, loud stereo,

I have a 2001 Wolfsburg 1.8T with the same problem, and if you troll the 'net long enough you'll see this is something Jetta users have reported consistently for several years now. I have taken mine to the shop 2x. Plugs replaced, Tune-up, lots of computer time and looking at sensors. Tonight, the thing barely runs and won't stop shuddering and lugging and trying to stall. It's also just started to smell (sort of a burning smell, but funkier). Back to the shop again. All I want to do is get it working and get rid of it. Let me know if you get a solution that sticks.

Is the Engine Check light on? vacuum leak maybe bad throttle body maybe Coolant Temperature Sensor maybe AND which spark plugs are you running? Some just like the factory ones! Makes a difference! ;-)

Yours sounds like the catalytic converter is clogged.