Quote:
Originally Posted by mattn
I have searched and seen similar problems, but I haven’t seen a solution for my specific problem…
The car is a 1972 911 with a 1986 engine and transmission. The engine revs between idle and a little over 1K. Just sits there continuously revving up and down while at idle. Sitting in the garage. At stop lights. It does it at first start up and after thoroughly warmed up after a 30 minute drive. Once underway the car runs great.
I’ve had this problem over a year now. Have brought it to a reputable (expensive and seemingly thorough) shop several times.
The following is a list of fixes over three shop visits (some don’t apply but just in case I’ll include them):
Spark plugs
Air filter
Fuel filter
Engine bay fuel lines (x 3)
Fuel pump, fittings and seals
Fuel tank (it was pretty rusted inside)
Fuel filter
Intake manifold gasket
Vacuum elbow
Intermediate flange (I don’t know what this is but I included it to be thorough)
Alternator
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It's a fuel mixture problem or the air screw in throttle body is mis-adjusted, or a non-stock chip.
Quote:
Originally Posted by mattn
Each time they insist the problem is fixed. But it never is. They are obviously thinking fuel supply. I notice what’s not mentioned in the list is the ECU. Could it be the shop was looking in the wrong place? I bought the DME/ECU from Vertex Auto in 2003 when I had the new engine and transmission installed. The engine is stock although I did delete the catalytic converter. I've owned the car since 1992.
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Not good!
Quote:
Originally Posted by mattn
I’ll mention a second problem because it may be related. This problem is annoying but not as annoying as the first problem. As I slow down in gear the car (engine) starts shuddering as the RPMs go below 3K. Hit the gas and it smooths back out. I should be able to go below 3K as I coast to a stop. This is new problem that seem like popped up around the same time as the first problem.
Any suggestions?
Thanks,
Matt
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Fuel shut-off occurring (on/off), typically less than 2K RPM. It could be a mis-adjusted throttle switch, or the DME ECU.