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mark houghton mark houghton is offline
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Join Date: Jul 2008
Location: Central Washington State
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Quote:
Originally Posted by T77911S View Post
i pulled the wire out of the connector to the CD for the tach/speed relay. at first it ran much much better. then i cold notice the miss in the 3k rpm range as i kept driving. then it got to where it was doing it in the 2k range. with the wire removed, for about 20seconds, the tach bounced up and down from 0 to about 2500. i had noticed it move about 200 rpm's once or twice before, so i checked the output of the alt, 14volts. i think i will put my MM on the battery and set it for record and drive around and see what it picks up.

this seems to be heat related too. when cold, it does not do it but it does not take long for it to start under normal conditions. (part of the reason i thought fuel/mixture related).
I'm losing track of your issue....too many things being done/disconnected, etc. Me thinks you're chasing your tail by now. I sure would be!

Anyway, what tach/speed relay wire is that you pulled (I don't run with a stock CDI, so not too clear). The over-speed relay is under the seat...is that the relay you speak of? Apparently, though, it has nothing to do with your tach, since your tach is still operating. But what got my attention was the tach bouncing from 0 to 2500 once the car got warm. That's usually a symptom of the alternator going on you. With that said, perhaps....just perhaps....you are seeing inadequate voltage to the CDI as a result, getting inconsistent spark as a result. Your plan to hook up a temporary DVM and watch it from cold to hot while driving, may point to a voltage change that coincides with your engine miss.

I once installed a temporary DVM to help troubleshoot a mysterious rotten egg smell and drastic drop in my AFR's just cruising in town under certain conditions. The volt meter would show way high charging when the symptoms showed up (boiling the battery). An easy obvious fix for me. Information is power....
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 04-23-2013, 07:14 AM
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