jbs

Hi Guys

My pride and joy is a 1991 model (M) C2 Tip with 125k miles, daily driver.

I just got new plugs, new plug wires, oil change, air filter, new distributor caps. Car ran very smoothly. Then next day (Friday) I had what, seemed like fuel starvation, which at first was intermittent but has got significantly worse to the point where the car is undriveable.

First the car is difficult to start, you have to massage the throttle to get it to start, then when you get it started you have to rev it hard to keep it from cutting out, then when holding the revs at say 3 or 4,000 the revs will go up and down as if you were putting your foot on and off the accelerator. When driving it feels as if it is cutting in and out and the only way to keep it running is to rev it hard.

The distributor belt is fine, replaced the DME relay - no change, battery is fine.

Lots of sound from the DME relay, sound from the fuel pump as well consistent with the change in revs. I understand the fuel pump is regulated by the DME/ relay and I assume the sound of the fuel pump is as a result of a signal sent to the DME/ relay which in turn is turning on and off the fuel pump. Is this a reasonable/ correct assumption?

Having removed the air filter and its cover the internal flap, which I presume is the air flow flap, is flapping wildly. Does this suggest that the AFM is the guilty party responsible for sending the signal to the DME/relay and then to the fuel pump. If it is the AFM is that where my real problem lies and if so what should I look for?

Of course I could be totally wrong and there could be some other reason for my problems. All comments, suggestions, recommendations, input, thoughts or P related philosophical insights welcome.


John

dfinnegan

Did you upset the electrical connection on the back of the AFM? Could be disconnected (though, it likely would not start at all), or too close to the metal hangers behind it. There is a TSB to tie-wrap the cable back on itself.

Also, will it start on either coil? Pull the igniter connection from the front of each and try and start to make sure both are still functional. Should start on either one.

BGLeduc

Most definitely carrier out the AFM wiring harness TSB, if it has not already been done.

Brian

Indycam

I would go back and look over the plugs , plug wires , caps , etc .
Has a wire come loose , is a cap / rotor looking funny ?
Can you see anything that might be causeing a cross fire ?

Rocket Rob

When is the last time you replaced the fuel filter? Maybe its clogged. I didn't see it mentioned above.

Indycam

I don't "see" a fuel problem in his post .
A motor with a clogged up filter runs ok at idle
and then starts to loose it as the rpm and need for fuel goes up .

911URGE

I had a similar issue with mine that developed overnight. Starts but would not idle. It would just die in seconds. I had to rev to keep it running. I cleaned the ISV & AFM and it was back to normal rock solid idle and running.

Also, have you checked the idle microswitch. May need cleaning or adjustment.

The AFM flap is spring loaded. Do you feel resistance like a spring is attached to the AFM flap?

jbs

Per the mechanic the ICU is the problem. When my car was running badly he put in one from another 964 and it ran perfectly.

Can the ICU be repaired?

If so any recommendations on a repairer in Ireland or the UK?

John

Indycam

The icu is the dme computer ?
If so , yes they do get repaired .