Hello list

I have a question concerning my -84 Carrera 3.2 (euro). When it idles, it feels a bit nervous, especially when cold. There are quite some vibration in the engine and in the chassi, and the car sounds (not to easy to describe the sound, it's ok to laugh) more like pop-pop-pop-pop-pop instead of a more even brrrrrrrrrr. There's nothing strange when I get the revs up, then the engine runs smoothly set aside some hick-ups when the engine is cold. The car has run 114.000 kilometers.

Is this the normal behaviour of the 3.2 engine? Or should it run smooth on idle?

Cheers

Christian

 

Mine (87) runs pretty smooth from cold idle to hot idle although may stuble a bit with a/c on.

When was the last tune-up? Could be a stack of things until you give us more info.

Cheers
Mark

 

It has been regularly serviced each 20.000 km since it was new. The last bigger service was about a year ago at 100.000 km about a year ago at an independent, but reputable, Porsche facility. Last oil change two months ago at 110.000 km. There's no AC in the car.
The engine starts very easy, always within the first 1-2 seconds and it never stalls. It's just that it seems to be a bit on the rougher side when at 800 rpm. I need to get it up to 1500-2000 rpm to run smoothly. I've had problems getting the CO up, it's now at 0.7 at idle, but I have been told it should be at 1.0.

/christian

 

Christian,

One thing that will cause a rough idle is vacuum leaks. Make sure all engine hoses are intake and properly attached to the engine, etc. Another area that is somewhat problematic on the 3.2 liter cars are leaking intake manifolds. Check all the 8MM barrel nuts that attach your intake manifold to the head. There are two barrel nuts per intake runner and they should be tightened to 18 ft lbs of torque. Do not over tighten these barrel nuts, because that can cause the intake runner to distort and cause an air leak. You need to get creative with your socket wrench (i.e. universal joints) to reach some of the barrel nuts. I check these barrel nuts on my '84 Carrera annually as part of my annual maintenance program.

Another thing that could contribute to your rough cold idle is valves that are out of adjustment. When was your last valve adjustment? Also, what is the condition of your plug wires, connectors, and spark plugs?

Regards, Bruce

 

I'll have these things looked into during my maintance later this fall.

Valves adjusted one year ago (10.000 km ago). New spark plugs then as well. Is there a way to check wires, besides shifting to new ones?

I'm not very good at engines, so I wouldn't know how to check the connectors.

Thank's for all the input.

/c

 

Ummm..what about these

oxygen sensor, idle speed control valve, speed sensor, air flow sensor, fuel pressure, air control valve, temp sensor 2, fuel injectors (check 10V), air intake leak, battery voltage.

These are all indicators of erratic idle according to the Bentley manual.

Good luck

Mark