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-   -   '79 SC develops miss/stumble as engine temp rises (http://forums.pelicanparts.com/porsche-911-technical-forum/369370-79-sc-develops-miss-stumble-engine-temp-rises.html)

Superman 09-28-2007 12:33 PM

An oven, on low temp, might work as well as a heat gun. Or better.

Tim, I experienced the Failed Permatune CD Box syndrome. When I figured that out, I placed a thread on the Classifieds page of this wonderful website looking for Bosch CD boxes. Garage sale prices are the only ones that please me, and I got some takers. A common price was $100. A couple were $50. One was free. They all worked. They are upwards of $2000 new, I believe. But again.....these things are lying around in peoples' garages and the swap meet price would probably be $200 or less. And quite frankly, based on my readings and discussions here and elsewhere, the Bosch units do not take a back seat to the alternatives in either performance or reliability.

Early_S_Man 10-01-2007 12:25 AM

Tim,

Most likely an intermittent Beru spark plug connector on one of your wires. If you have a shop put it on an old Sun or Delco engine analyzer [and compare the waveforms for all six] when hot and exhibiting the problem ... it should be obvious. Or, you could pull the plugs after it has been missing ... the missing cylinder will have a carbon-fouled plug!

Tim Hancock 10-01-2007 03:11 AM

Quote:

Originally Posted by Early_S_Man (Post 3507191)
Tim,

Most likely an intermittent Beru spark plug connector on one of your wires. If you have a shop put it on an old Sun or Delco engine analyzer [and compare the waveforms for all six] when hot and exhibiting the problem ... it should be obvious. Or, you could pull the plugs after it has been missing ... the missing cylinder will have a carbon-fouled plug!


I am going to pull the plugs when I get a chance Warren and most likely fashion up some new plug wires. I drove it a short distance the other day, and even when cool, it now seems to be only hitting on 5 when I put my foot in it. Makes sense that a plug is starting to foul if has been getting less than optimum juice thru a bad plug wire.

I need a week off work to catch up on stuff! :D

Tim Hancock 10-09-2007 03:31 AM

Quote:

Originally Posted by 1982911SCTarga (Post 3503642)
My money's on one or more fading plug wires. Ohm up to the problem.

Brian


Well, I actually spent an hour last night on the SC. The first wire I checked was #1 and it was bad. All the rest of the wires were 3.5K - 3.7K ohms. I pulled the #1 and #2 spark plugs assuming #1 would be fouled, but it looked about the same as #2 :confused:.

I disassembled the #1 plug wire and found that the 1k ohm connector on the dizzy cap end was no good. I grabbed an old Chevelle wire set off the shelf and swiped the simple dizzy end connector from it and soldered and crimped it to my #1 wire. I feel like a real dumb@ss about now (a Homer Simpson moment..Doh!) as the car runs awesome! I am guessing that this connector has been going south for quite some time as I don't remember this car pulling so hard.

bad connector and old Chevelle wire about to lose it's connector.

http://forums.pelicanparts.com/uploa...1191929346.jpg

http://forums.pelicanparts.com/uploa...1191929397.jpg
http://forums.pelicanparts.com/uploa...1191929454.jpg

Greek55 10-09-2007 04:41 AM

I had a similar problem with my car, but only when RPM's went over around 4000. WE changed everything, plugs, fuel injectors, wires, rebuilt distributor and nothing helped. Wrench then said to try a new warm up regulator. That fixed it. I made an agreement with parts guy to take the WUR back if it didnt fix it. He insisited that the WUR would not have anything to do with the motor missing when warmed up. Maybe he didnt want to go to the trouble of shipping the part knowing it might be returned.


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