Ok, here is a problem that has been plaguing my 911 for over a year now. I have had it at some very qualified mechanics and they have not been able to figure it out.

It is a problem that comes and goes and of course I can't get it to happen in front of anyone who knows more about engines than me or even in front of a video camera for that matter. It can be a simple annoyance all the way to making the car undrivable. It seems to come and go at random. When I go to start the car I never know which car I will get. It is a Jekll & Hyde situation.

First off the equipment. 84' Carrera stock 3.2 motor. Re-built when I got it. I have put 20k on it so far.

Now the symptoms, The engine will lose power, the tach will start to come down then all of a sudden it will "catch" and go back up to normal. There will be an audable "clicking" sound from behind the dash. Like around the oil temp guage area. This is all during idling

When driving it will lose power and then "catch" making the car jump like a "new to stick" driver is driving. It kind of violently jerks. Sometimes during these bad moments the car will stall and will not restart.

None of this happens at speeds above 40 MPH

I recently had the ignition switch replaced when we thought it was that, we also replaced the hazzad switch as well. It worked fine for 6 months then Blam ! It was back. There goes $600. I have also replaced the DME relay.


When the car is having a good day, It runs perfectly. All speeds and is a joy to drive. I drove it today for an hour and it was fine, I ran it through a range of speeds and revs on the tach with no problems at all not even a blink. If I start it tomorrow I have no idea what I will get.

I don't know if it is Electrical that seems to make the most sense. It occured to me that since it comes and goes and since I hear a click from behind the dash could it be two wires from one of the gauges touching each other ?

Please any suggestions will help, I love this car and really want to drive her more. I am so sick of having this problem.

Someone on another fourm suggestion the crankshaft sensor, I have just looked at the all of the connections and they are all clean and fitted tight. I am Not sure it is that

 

I have never heard of anything behind the dash that would short out to cause an issue. I would have the reference sensor and head temp sensor checked first.