My 80' GTSI is with mechanic now for backfiring at idle along with bucking pretty harshly on accelleration. Initially, he thought that there was a problem with fuel injector being clogged or even a bad plug wire, but now he thinks that there is an issue with the timing being different on the banks....there are "boxes" which control the banks (2)??? He feels that one of them is not working properly. Since he is so busy this weekend, he probably won't get to it until next week...so in the mean time, I am wondering if any of you knows what he's talking about and can explain it to me! He was working so I didn't want to pester him with questions. He told me that it wasn't a big deal and not to worry about it, but you know how that goes...like seeing your kid sick and the doctor telling you the same! Thanks, Frank
I really have no basis for answering this, but I'll make up a response. On my 1987 3.2 the rotors are directly affixed to the end of the cams. In most other cars of this vintage there are mechanical functions that allow the rotor to vary from the cam thus creating advance, or retarding the spark to spark plugs based on need. I won't go into why an engine needs advance. In our cars because they are fixed a computer of sorts makes all these decisions. It sounds like your mechanic is saying there is a glitch or failure in this computer portion that is making the timing incorrect for various engine speeds. The spark will then come at the wrong time and have less than desirable results. That's my take on it. Good luck. Your mechanics certainty makes it sound like a pattern failure based upon symptoms.
Could be one of the digiplex ECU boxes went bad. I had a similar problem which went away with a new unit installed.
Thanks fellas! Taz, Your answer sounds more like what he is telling me. He also said that they are hard to find and might need to be rebuilt. I'll let you guys know. I see that you are in Conn...is Bill Pollard your guy??
Furio, There's one thing to check before replacing a digiplex - add an external ground wire from each of the digiplexs to the bracket at the back of the plate to which the digiplexs are mounted (not the front bracket as it's not attached to ground). There's a few threads on here how to add the ground wire. Good luck!
I hope it's not what you guy's are talking about!! I looked up "digiplex ECU" and the are over $1,000 each!! Ouch!! Are they re-buildable??
