Stumbling/Stalling Jetta Carat

Ha, I have the exact same model and year, in for paint this week. Could it have jumped a tooth on the belt? Is it like that all the time now or is it intermittant?

It's an intermittent thing......

Correct me if I'm wrong but don't the distributer's in these cars adjust timing advance when it is required? Sounds like timing , for instance my car when hot pings like a SOB after I start it again, if I put in neutral and rev it it advances and makes the ping go away. Just a suggestion. I've driven them with IAC motor's disconnected and never had the problem you are describing.

I won't say that. Mine for the most part has been bulletproof.

I have a similar problem to yours Peter. Mine starts easily, but when the engine is cold it doesn't rev easily and acts like it's not getting fuel. It's also idling about 750 rpm... when it's idling smoothly. When it warms to a certain point, all is well and it runs perfectly. This started after I replaced the timing belt (made sure no pulleys moved while the belt was off), and since then have replaced fuel filter, plugs and wires, and adjusted the idle screw on the manifold which helped a lot. It's not as bad as it was at first, but it's still irritating, I can sometimes still smell raw fuel, and my fuel mileage has gone down 10 percent. I'm out of ideas. Anyone have a solution?

Thanks, Todd Topeka KS

1990 Jetta Carat, 1.8L PF, 5sp

Are you POSITIVE you have that timing setup bang on, if it's out a tooth it will run like shiete.

Check it again Todd, I'll lay money down that something in the timing is messed up. If it didn't do it before you changed the belt and it did it after, something is out. Check and recheck.

If you are out by a tooth you won't get missing, maybe some pinging but timing adjustment can get rid of that. Is it timed properly? Did you adjust it at 2000rpm with the coolant temp sensor disconnected?

I have no idea. Never have owned a timing light.

How critical is the tension on the idler roller? I replaced that with the belt, and at first thought I had it way too tight, so I loosened it.

Critical enough, too tight might cause premature where of the belt and wear out other compnents like the tensioner. They say you should have 90 degree deflection when the belt is tight enough. You should be able to grab the belt and twist it 90 degrees in either direction when it is tightened properly.

these things I experienced which caused exactly this on digifant...

an electrical connection problem at one of...

1) the grounds near the drivers side rear of the valve cover 2) the maf sensor (i.e. air flow flapper in the air filter housing) 3) one or more spark plug wires cracked... sometimes you can hear them crackling but not see them w/o misting them w/o water at night...

IIRC, idle speed is adjusted by a screw >I hate my Jetta...

Brad, thanks for telling me to go back and check the belt. The camshaft pulley was at worst a half tooth off- not worth messing with, but I adjusted the intermediate shaft one tooth and that made all the difference in the world. I'll have to watch the gauges more now- hit redline amazingly quick in 3rd gear, and hit 130 km/h on a freeway run without really trying. Fuel economy should go back up- provided I can keep my foot out of it. It's fun to drive again. :)

Thanks again, Todd

No worries, just by what you described it sounded like a tooth. I believe the intermediate sprocket drives your distributer (not positive) or it could be a balance shaft.

Peter,

I had been having the same problem on my '86 GTi for the past several months and finally figured out what the problem was.

The boot that connects to the throttle body had a crack on the bottom where I couldn't see it. This was letting in more air than was being measured back in the filter box, so the mixture was too lean. Every time I'd step on gas, it would just about die.

I replaced the boot (about $5.00 for a new one) and it runs great again.