Please help!

I have a Golf III 1.8 GL with ABS engine. For two months now I have>had big problems with my engine and the car has been in and out of>Volkswagen auto repair ten times without finding the problem. This has>become very irritating and I have now decided to do the work myself.

He said it was a Golf III 1.8 GL with an ABS engine so it > can't be '85-92. > It's probably the 1.8 that non-US A3s got.

The sympthomes I guess can be caracterized as "changing/unrealibl­e> igniting timing". In paricular the problem occur if the weather is> cold, wet and/or misty.

I suspect the problem could be the hall sensor, but I do not know for > sure.

Ok, if you want to look at the problem yourself, I can try to > explain > it works ­ Your car is equipped with Monomotronic fuel > injection > system, which is somewhat funny: a very primitive hardware and > a very > smart ECU. Yankees call it "throttle body injection" ­ >

First, what tells the ECU itself? Any errors? >

Second, I would look at the obvious - air leaks. Your symptoms > do not > suggest it, but anyway... There are only two places where it > could > happen: the rubber "basement" of the injector unit (it cracks > sometimes). Just swing the injection unit with your hand and > look. > The second place to look is two thin plastic tubes (the ends > of them), > which are comming from the back of the injection unit and > going to the > coal container which is located under the air filter box. >

The next (most probable) thing is the sensors and wiring. > There are > not much of them, and the most are monitored by the ECU. > 1. Coolant temperature sensors, located on the upper coolant > eee... > "tube" ­ If you disconnect the plug, ECU will think "it's > cold" and > rpm's will rise to ~1100. Just try it when your car starts to > behave > funny. If nothing is happening, then the cause is probably > somewhere > else. >

2. The injector, or more likely the plug and wires. If tou > look at the > injection unit, then there are three plugs on it: if you stand > in > front of the car, then left (or passenger side) the is a > stepper motor > (idle stabiliser) with a plug on it, then in the middle is a > brown > plug for injector and air temperature sensor, and finally > right > (driver side) - a trottle body potentiometer with a plug on > it. > It happends sometimes (I had this problem last week), that the > wire > just breaks off inside the plug, but stays semi "connected" > most of > the time. So, just "wiggle" the connector with your fingers > sideways, > try to pull the wires etc while the engine is running. If your > engine > dies, then you found it. > My car also started to behave funny, idling at ~500rpm, > jumping rpm's, > "jerking" and so on. But only sometimes, once every two of > three days. > No ECU errors, nothing. The problem was a broken wire in the > injector > plug. >

3. Throttle body potentiometer, the most expensive part after > the ECU > (400 euros or so ­ > It it basically the only information source, from which ECU > knows how > wide the throttle is open. Check the plug and wires. >

4. Coal container. Unlikely causing a trouble, but you can > temporarily > "disconnect" it by taking those two thin plastic tubes off, > and then > somehow "hermetising" the holes. >

5. Lambda. No problem there as it was changed. >

6. Stepper motor used for idle stabilization. I can't imagine > it > causing such problems. >

That's all, as I said, the Monomotronic is a very primitive > thing. >

Hmm... doesn't look like they know what they are doing ­ >

I would say - check your wires and plugs. Wiggle what you can, > pull > what you can and so on.

Now I have changed the coil and the cable from the coil to the> distributor. Still the engine behave strange. I have also tried all> the suggestions in the previous postings without finding the problem.> Another strange thing I observed is that the engine lacks power at> high rpm and around 5000 rpm the engine "shuts down" until it falls> below "4000" rpm.