Frankly

My 964 has a problem. -Most of the time engine works well, once it stopped, worked a little time on idle, but when pressing gas pedal, it feels like no fuel - or a lot too much fuel. But some time it works normally, starts up normally when cold - or hot. I replaced a fuel pump, and I drive today about 100km, and everything worked normally, until it stalled again. -And idle was very rough and doesn't reply much gas pedal..

After a while, it worked again normally. -But some problem there is and must be solved.

Before I have changed igntion wires, coils, distributor caps & rotors, spark plugs, lambda etc. -I checked emission today too, everything looked ok. DME-relay is replaced too.

Any ideas? -Problems with AFM?

Sorry my english.. Please try understand

Steve Weiner-Rennsport Systems

Check your idle switch (its on the side of the throttle body) to make sure its closed when the throttle is closed.

Clean the contact wiper on the Airflow Meter.

Make sure your DME relay is working properly!!!

fenixv8

Also did you replace fuel filter when you changed the pump?

Kuchar

If You push a little just a little the pedal are revs going down?

Frankly

Nope, did it last summer. Original part.

Nope, revs goes up normally.

Now i installed other AFM (from ebay, haven't try it other car myself), and it works a lot better! ...until.. yesterday, I noticed again that issue. After start, engine stalled again. Started normally, and drive few meters and engine like died. Started, and worked well. -I've maybe dreaming, but I think sometimes (when warm) and accelerating hard, engine knocks a little (hearing that pinging sound) -So still thinking it fould be fuel problem. -Ofcourse, this "new - old" AFM could still be a problem.
(ofcourse, haven't drive much becouse I know pinging isn't good thing..)

Injector problem? Fuel pressure regulator i did check too, and did'nt notice fuel leakage.. Could durametric tell anything for me? Issue is still random. Not depending much temperature. When issue is on, car feels maybe little "slower" than usually.

Navaros911

Hook up the diagnostic computer and check what the values are registered by mototronic.

Your idle switch may seem to work fine, but you don't know it is registered by the computer. Running a diagnostic check will tell you straight away. Also easy to check ISV with it.

Seems like electrical. Could be a bad wire somewhere or a contact issue.

It's almost like an art hunting these issues down, durametric or PDT999/UDT999 helps a lot.

Frankly

Measured fuel pressure from fuel rail. Pressure is ok i think, about 3,6bar when idle.

About 12hours later, there's no pressure anymore. -Is it normal?

I'm getting serviced injectors soon, so propably i will install "new" injectors and replace o-rings too.

sml

I dont think this is the cause of your problem, but make sure you do a system adaptation each time you reconnect the battery.

John McM

I'm getting my windscreen replaced at the dealer this Friday. I will get them to check my fuel pressure at intervals as well. Right now I suspect something is leaking pressure out giving warm start problems.

Frankly

How that system adaptation is done?

John McM

It's a function on a special mechanics computer. There's also a freeware called scan tool that some of us use with a special cable.

You warm the car up and then select adaptation on the software. Not sure exactly what it does but it's a possible solution to make engines idle better.

sml

This is incorrect.

The system adaptation is essential for correct idling.

I spent about 12 mths and hundreds of hours trying all the usual options to improve my idling. The last attempt was a system adaptation ... 5 mins and the result was perfection.

John McM

With all due respect it is not incorrect. I said it's a possible solution, and my response is correct based on working on multiple 964s with the software to do adaptations.

I'm not sure what your assertion is based on except that it worked for you on your car, but I have experience over 15 years of 964 variant ownership. My Turbo 3.6 idled perfectly when restarted multiple times over 7 years of storage with the battery disconnected in between without a single incidence of idle adaptation ever being required.

On the other hand I have completed adaptations on three often driven NA 964s, including my C4 where symptoms of random stalling were not fixed by multiple adaptations.

I would say however say that adaptation is a logical start for me as it is quick and costs me nothing.

Frankly

Hmm.. I checked fault codes with Durametric, and there's fault code 32, Knock Sensor #2. -Ordered new part.. so let's see..