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Tue Apr 11, 2006
19:22
A couple weeks ago my Golf (1991 Digifant 8v) started to act up a little bit. It was nothing terrible, just a "cough" or "sputter" that happened two or three times that first week. Each time it happened, I had my headlights on and it was damp and/or raining out. Naturally, I had concerns at that point that it was an electrical problem. The following week, we had some great weather and the problem seemed to get worse. Every morning that week was a little chilly and I never had the problem on my way into work. Every evening, though, the car would momentarily cut-out several times on the way home. By "cut-out", I mean the engine stopped firing completely for a split second and then would come back to life just as suddently. It always seemed to happen after the engine was warmed up, but only during fairly warm ambient temperatures. I knew the ignition timing needed to be checked, and I had never taken care of my electrical connections in the engine bay since buying the car (this is worth doing on any older vehicle, but especially for vehicles with sensitive engine management systems, like Digifant and Motronic VWs). Before going any further, I decided to finally address those issues - they're easy to do and there was really no reason to keep putting them off. Checking and adjusting the ignition timing is a little different on a Digifant VW - you should consult your Bentley manual for specifics. In addition to a couple of other prequesites, the timing must be checked and adjusted with the engine between 2000 and 2500 RPMs rather than at idle. So if you don't have a friend to operate the throttle and keep the RPMs in that range, then you'll need an external tachometer that you can keep an eye on while you operate the throttle body directly with one hand and operate the timing light with the other. Once I finished that, I went through the tedious process of disconnecting all of the electrical connections under the hood that feed back to the ECU and ignition control module, cleaning the contacts with some emery cloth, applying some dielectric silicone grease to each contact, then reconnecting them. Then, just for the heck of it, I pulled off the distributor cap to take a look at the contacts in the cap and on the rotor. They were getting pretty corroded so I cleaned them up as well. Since finishing all that, we've had several days of great weather and the problem appears to be gone. My guess is that the condition of the rotor and distributor cap contacts were most of the problem - but that's just a guess.

I know Digifant VWs have a bad reputation, but I think that's largely undeserved. My Digifant has been the best running VW I've ever owned - it even has better throttle response than our OBD-II Motronic Golf (although it doesn't idle as well). After owning this Golf, I no longer believe that Digifant is an inferior engine management system; in fact, I now consider it to be superior to CIS and CIS-e. Driveability problems and poor performance absolutely do not need to be an issue with a Digifant VW. I have heard that Digifant does not cope well with very aggressive performance camshafts, and I certainly believe that. The same seems to be true with the later Motronic VWs as well. I don't have first-hand experience on that, though (not yet anyway).

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