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Hello all
745 Turbo 210K miles in very good shape, I've had it since July, original owner kept all reciepts. Very well maintained, and second owner did a little hot-rodding. Dawes device set to roughly 12-15psi, "timing advanced" by their mechanic. I didn't ask many questions as the car ran great at purchase and drove without incident all the way from Fort Lauderdale Florida to my home in Connecticut.
I was pretty happy with the performance of the car but in the back of my head I debated removing the Dawes device to drop the boost back down to stock. I was a little leary of blowing something as I have a bit of a lead foot.
About a month ago, driving back from work, I raced the car a little bit and embarrassed a young Volkswagon driver. Nothing I hadn't done to the car before and certainly nothing I had never done in my apparently bulletproof '88 745T. A few miles down the highway and I noticed a misfire in the engine at lower rpms- noticable below 2000 rpm, and very noticable at idle. I got home and was worried I had finally damaged the car by leaving it at high boost with me behind the wheel.
So after checking the plugs and finding them all nice and even, I let the car sit while I debated projects like new head/new motor. I finally drove it over to my parts guy who said "sounds like an ignition problem".
I have some time right now, so I read the FAQ and checked the throttle body- clean as a whistle. All the hoses are intact, and I checked this by removing all the large hoses, cleaning them, and re-installing. No difference.
Today I went for a new cap and rotor (parts guy didn't have wires) and I found two things- the coil's mounting strap was quite loose, and the ignition timing was advanced off the scale. I fabricated a nut and bolt to fasten the coil to the strut tower reinforcement, and retarded the timing as much as possible. The car runs much smoother, no miss at idle or below 2000 rpm, Dawes device pulled yesterday.
A few questions-
#1 HOW do I get the timing back to 12 BTDC? I wish I had checked the timing before I had a problem. Is it possible that the timing belt jumped and that's why the timing is that far advanced, or is there some way the past mechanic could have rigged the distributor to run so far advanced? (guessing it was around 30-35 BTDC before changing today.)
#2 Does the ignition coil ground to chassis simply through the negative primary terminal, or does the mounting strap also provide a ground path?
#3 Could some other device (ie knock sensor) be damaged/shorting in such a way that the ignition system thinks it should advance the timing? The change in the engine's behavior was definitely caused by something that happened during the course of that drive home...
Thanks for any input-
Dylan
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