jotz

Please help, when i'm driving my 1991 964 c4 it just seems to loose all response from the pedal. it feels like the car has stalled. if i try to accelerate it don't do nothing for a while, but if i push the pedal to the floor it picks up with a burst.i give it a rev and it is ok.the exact feeling would be if you were driving along and you switch of the ignition; then switch it back on again. Please can you advise me. thanks

Kevin

Jotz
Does it feel like a miss. The fuel injection relay, could be starting to give up, usually it is more sudden. How did it run prior to your problem. Distributor belt. Fuel injector clogged. Any check engine lights? Does it smooth out when warmed up. How many miles since a major service?

Randall G.

Hi Jotz,

You should verify your distributor belt is intact, if you haven't already.

See the recent thread "Poor Performance/Good Performance" for more
information.

Adrian

Dear Jotz,
First thing to do is check that relay R41 is working. You are suffering a complete loss of fuel. If the secondary distributor belt has failed, it may also contribute but you will have starting problems as well. Slow to start.
Unfortunately there are many possible failures so start with the obvious first.
No power means no fuel or no air. It is not stalling so I do not suspect the air because the fuel would flood the engine and stall it.
I suspect no fuel so start with the relay and then the fuel pump.
The fuel pump runs all the time from the instant you apply power. Try listening for the fuel pump. Can you still hear it running,
Ciao,
Adrian
911C4

Raymond

Hi everyone,

I think the same thing's happened to my 1990 C2...it started only yesterday as a little hesitation when accelerating. As it happened near my intended destination, I parked it and hoped that I was being overly sensitive, because the engine has been perfect since I bought the car 6 months ago.
When I next drove the car a couple of hours later, it felt normal at first and then it began to feel jerky when I tried to accelerate (got worse as it warmed up). Then it started to stall, and as Jotz described, felt like it "lost all response from the pedal". It would start after cranking for a while, and would pick up "with a burst" or not at all.
I decided to get the car towed to the Official Porche Centre, where it will be looked at tomorrow morning.
My car has just had a major service 2 weeks ago, and also had a new (rebuilt) distributor with ventilation kit fitted about 2 months ago. I do a little less than 1000km a month.
I'm a little worried about what the mechanic might say...may I ask:
- what's the update on what happened to your C4? What did it cost a lot to get it fixed?
- If they manage to find the cause of the problem, is there any reason to suspect that the little episode has done any damage to the engine?

Would appreciate any advice
Thanks
Raymond

FlyYellow

Raymond,

I'd be really interested in hearing what happened to the car. Can you please post a follow up....

Cheers,

Boris

horst

A VERY similar thing happened to me some months ago, and was **expensive** to trouble shoot. I checked all the obvious things- fuel prssure, fuel quantity, relay, head temp sensor, distributer belt, injectors; all checked out OK. Finally, I bit the bullet and took it in. The shop took a long time to trouble shoot-hence the high $$$- they even had the hammer. Turned out my car had TWO problems simultaneusly: Faulty flywheel position sensor and one bad coil. Car has been running great ever since.

horst

Another thought also come to mind, although I don't think it is a factor here: Check in the engine compartment, just above the throttle linkage. That soundproofing material just above the linkage can and does deteriorate, fall down and interfere with the operation of the linkage. That can also be dangerous. Either rip it out, or replace it. A "Bridge strap" can be fabricated as I did to cross the soundproofing, screwed up by the original fastening *****, which makes the thing stay up much more securely. Doesn't look bad, either.

Bill Wagner

I had similar problems on two other cars. In one case the fuel pump was in the process of dieing, and in the other, the fuel pump pick up filter kept getting sporadically clogged by junk in the fuel tank. The latter problem would almost always occur when the tank was low on gas, and giving the gas pedal a good pump could make the problem disappear for a while.

Bill Wagner

Roman Mayer

I had a similar issue with loss of power and surging. It was a bad coil.

FlyYellow

How do you check for a bad coil?

Raymond

Hi, thanks to all for your advice. I spoke to the porsche agent about my car and they told me the following...I would be interested in your views on whether it makes sense:

- the morning after I towed my car in, the mechanics tried to start the car but could not...eventually they had to push it into the service bay
- they then proceeded to check the distributor (which I just replaced with them 3 months ago), it checked out OK...the belt was new and in place and everything looked fine.
- they then put the distributor back together, and the car then seemed perfectly normal!
- the service engineer told me that the items I mentioned to them all checked out OK (relay, fuel pump, and some sensors(?)). They suspect that it could be a rotor in the distributor that was jammed or something, but everything seemed fine now.
- just to be sure, they will continue to keep the car another day or so and run it around to see if the problem recurs. He said that if it was an intermittent fault on any of the possible components, it would not show up on their diagnostic equipment unless the problem was actually 'in progress'.
- no charge so far for the work done because the distributor is still under warranty and they have said that it could be the culprit
- no compression test suggested as the engine runs very smoothly and is not down on power.

Will post their final 'verdict' when I collect the car from them.

Thanks to all
Raymond

Adrian

Dear Boris,
There are two checks you can do,
1/. Stick your tongue across it and if your eyes do not light up it is broken. If your eyes light up move on to something else (Just kidding folks, do not try this really).
2/. Swap the plugs on the coils over. You have two. Mark them before you do this #1 and #2. Then start the engine. If you have the bad coil now in the #1 position the 964 will not start.
3/: Carry out a resistance and insulation check. Enusre connectors are removed before doing this check,
Ciao,
Adrian
911C4

horst

Adrian! Suppose Boris misses your "just kidding", and puts his tongue on it! I believe you are a closet proponent of Social Darwinism! (actually there is something to be said for that)

FlyYellow

Adrian,

Thanks and I'll make sure my tongue is really wet before I try this.

I was under the impression that the coil produced a spark, but that it was insufficient to detonate the fuel for some reason. But the easy way is to unplug the coil wire and put it against the case. If it produces a spark then I'm good.