Porsche Enthusiasts Club Forum

Ok.

So spent Sunday repairing the electric windows, with success. Also fixed the wipers so they now park.

Today, came to start the car and it turned over, caught for perhaps a single rev, then just turned over not firing.

So removed the DME and jumped it. Still the same, turns over but will not fire.

So disconnected fuel pump and provided it with 12v, and the pump runs.

Tried the engine again, and it caught like the first time but then just turns over. The fuel pump doesn't run.

Checked the voltage at the pins on the edu as per Clark's Garage. All ok.

Tested resistance at the speed and position sensor plugs, all ok. Still will not start.

The fuel pump is not running and I am at a loss as to why.

Any thoughts?

I had very similar symptoms, eventually sorted by replacing the ECU.

Thanks.

Just to add I have tacho bounce when cranking.

I did open the ecu. It was still sealed and looked ok. The only thing I did, not sure it has any bearing, was the battery got flat working on the windows and wipers so I put the battery on a conditioner over night whilst still attached to the car. Something I do on all my cars with no ill effects so I am assuming this is nothing to do with it.

Could it be the immobiliser?

I don't even think it has one - how would I tell? Previously, I've got in, turned the key and its started.

Same here

AWwwwwww, bum. Guess I just buy one off eBay and hope for the best.

By way of update I had to leave the car in situ at my 924 owning friend's house. Given the consensus on the ECU I asked him to check the part number on the ECU in the car just for safety. Which he did, and then thought he'd give the key a turn.

Guess what.

Started.

Good on the one hand but a pain on the other as I don't know why.

My thoughts are that I was topping up the coolant with a mind to bleeding the system and I had the bleed screw open. I think water had flowed out the bleed screw and ended up on something that prevented the car starting - until it dried. Plausible? The coolant temp sensor is down there in the area where the coolant would have gone. Could that have got wet and stopped the car from starting?

Wish I knew why, but apart from that, all smiles again. Now onward with my long list , ,. . . . . . .

The trouble with faults like that, which just go away by themselves, is that they can dent your confidence in the car.

The easiest way of checking the ECU is to try out a known working one if there is a friendly 944 owner nearby; they're easy enough to swap.

In the case of my ECU fault, I sent it off to David Barker at Berlyn who was able to confirm that it was faulty and supply a replacement. Now I need to decide whether to get the old one fixed just in case.

You're right. Spent the day moving the car around. Fitting a new exhaust (yummy). Onto the ramp off the ramp. All ok.

Set off home, all ok.

You can see where this is going.

Stopped for fuel round the corner from home. Filled up.

Wouldn't start. Exactly the same.

RAC came. Tested for the usual stuff. Pump ok. In the end he rigged the rear lights to the fuel pump so it ran when I turned the lights on and that allowed me to drive round the corner to my house.

So I guess it still has the feel of ECU (although the speed and thingy sensor are not ruled out).

i had something like this went through dme relay s/h ecu ect and while getting cheesed off looking for fault i looked at repairing my intermittent indicator so had my fuse box half out on blocks of wood and found loose wire and soldered it she ran fine ever since
touch wood
http://forums.tipec.net/viewtopic.php?f=25&t=17069#p120473
if you got half an hr to kill lol

thought I'd post and update.

Well, I posted here http://forums.tipec.net/viewtopic.php?f=25&t=19908 looking for any relationship between the DME temp sensor and starting the car.

I've done a bit of testing.

I tried to start the car and it just turns over and does not fire.

I 'hot wired' the fuel pump and the car starts.

Removed 'hot wire'

I disconnected the DME temp sensor and the car started

I plugged the sensor back in and the car wouldn't start

Repeated - all results the same.

As you can imagine I've ordered a new DME temp sensor.

Fingers crossed . . . . .

Lets hope you are on the way to starting all the time.
There is nothing so annoying than a car that sometimes wont play.

Good to have the feed back, so often folk dont say what the fault was once they sort it out.

Had a faulty ECU temp sensor ,fine when cold but because the sensor was faulty the ECU thought the car was still cold when it was warm and kept pumping fuel in hence no run.

Was the temp sensor on the coolant or was it inside the ECU?

Yes I really dont understand much about electrics