Strange problem - cuts out at 3600 rpm
 

All of a sudden a problem has ocurred with my 1984 Euro Carrera 3.2. As I was out driving in the great summer weather the engine suddenly cut out at 3600 rpm as if the rev limiter had moved itself down there from the usual 6500 rpm. The cut off felt quite powerful and made the engine and gear lever vibrate. As long as I changed gear before reaching 3600 rpm the car ran fine. As I later tried to rev the engine past 3600 rpm the same cut out ocurred again. At one time I managed to get the revs past 3600 rpm, but it caughed at lot by that (when passing the 3600 mark). However as I was past 3600 rpm it ran beautifully up to 5500 rpm where I changed into third. It seems the problem only occurs under load. When parked in the driveway I tried to rev the engine in neutral. No problems at all...?

What can be wrong? The fuel filter and spark plugs are almost new. If it was the fuel pump the car wouldn't run at all, would it?

Could it be the rev limiter that has gone nuts? If yes where is it located? Is it built into the DME or is it a part of the rotor in the distributer? Or..?

I really appreciate any advice you can give. :confused:

Mikkel,

Have you checked your air intake for occlusions? A partial blockage here might cause the symptoms you describe.

I have a cone shaped K&N so I don't think it's a block in the air intake.

I've just had the 3 year old distributer cap off and looked inside. I could see some small black patches of "dirt" (?) on the contact points. Should I scrape that off with a screwdriver? The same age rotor looked very clean.

You said the magic words "under load". Therefore I would suspect a spark condition. I would replace the cap and rotor first, then closely examine the wires. Put dielectric grease on all spark plug boots and in all rotor sockets. Hope this helps.

Missing under load could also be from fuel system.
 

With the same symptoms, my problem ended up being a bad warm up regulator. I put in new fuel injectors prior to replacing the wur and it helped. I have also heard of fuel distributor causing the same problems. I would tune up with new wires and fuel injectors first, if it has been a while. Then, if that doesnt fix, have a Porsche machanic check the Warm up Regulator, Then if that checks out, the fuel distributor.
Good luck. This kind of problem is very frustrating to fix.

Try checking the cyl head temp sensor and that its wires are properly plugged in. It's probably worth replacing it and the dme relay on general principles. If you take it to a Porsche mechanic you need one that knows 3.2s, the latest generation of mechanics are lost on this type of fault as they can't use their diagnostic computer.