not starting

[Guest]

second time shes done this now and im really hopeing theres a miracle cure so to speak lol

first time it was outside my work and couldnt leave it so conected up a set of jump leads to another car cleaned the plugs and just sat there with the starer motor turning over with the accelerator going from not on at all to full throtle till she eventually started took quite a while and i sadly had to show no mercy to the starter motor to achieve my goal!!

since then i have changed the plugs/air filter/and dizzy cap - current leads look rather new and in great condition

went out to her today and jump in the car everythings same as usual battery oil all good,, go to start her and she just wont catch,,starter motors turning over good as gold but sadly she just isnt springing to life,, foot to the floor and she tries to catch just sadly doesnt

any ideas whats up?

all has symptoms of for maybe the first 1-2min of first being started i have to sit with my foot on the accel to make sure she sits at 1000 rpm otherwise she cuts off

car is a 1989 2.7 auto

thanks

stu

 

[944turboS]

Can you hear the fuel pump running before you crank the starter? If not then it is probably your DME relay if yes then it could be the crank sensors

 

[Diver944]

Definitely try the DME relay, my S2 has worn out two in the past eight years.

They are under £20 from an OPC or independants (I carry a spare one in each glovebox)

 

[Guest]

guys excuse me for not knowing but what is a DME relay and its function??

cheers

 

[berg944]

One of its functions is a fuel pump relay.

Look in the fuse box, it is one of the bigger relays and might even have DME written on top (if not use the diagram on the fuse box lid)

I would recommend you buy one anyway, try it and if it works buy another one as a spare.

If it is not that at least you have your spare and not wasted any money.

Mike[:'(]

 

[Guest]

ok sounds promising

 

[chris_boyle33]

My car is sitting in a 24 hour garage near my homebecause it won't start. [] It drove to the garage fine, restarted immediately at the garage fine but then wouldn't restart 4-5 mins later when i'd filled her up and paid for the petrol. She'd previously been running with a misfire.

She fired energetically but would never be able to keep running. I've charged the battery, put in a new DME relay and still no joy (now not even showing interest in starting). She's turning on the starter ok, sparking and smells of fuel. [8|]

I'm trying to work through the Clark's garage list of suspects including engine temperature sensor and crank sensors. I'll replace the HT leads and distributor cap too which all look suspect.

Chris
------
I do feel guilty about only posting here when my car doesn't works. it just seems to break so often that...

 

[944turboS]

Sound like the crank position sensors to me

 

[Fen]

What Graeme said.

 

[944Turbo]

Do you still get a spark with dodgy crank sensors? I had a feeling the signal from the crank sensors was amplified to create the coil signal and therfore sparks but I could be wrong. Could it be too much fuel - ISV/AFM or FPR related or not enough fuel?
Tony

 

[Fen]

I think you might still get a spark at the wrong time if it's a crank sensor, although commonly you get none at all. It depends if the EMS sees a fault (no spark) or doesn't (wrong spark).

 

[skendrick]

I had lots of problems with my car when I first bought it and it was the crank sensor, I would hear the alarm beep and the car would cut out and not start. This was the crank sensor too and all problems were cured. They cost around £70 for the part.

Steve

1988 944 Turbo

 

[chris_boyle33]

I did a fair bit of watching sparks and thinking 'is that sparking slower than it should or not?' Perhaps it was. Before the leads and distributor cap were fiddled with i could only get a spark on one plug. Perhpas that is a position-sensor type fault aswell.

Thanks for the help y'all,

Chris.

----
Well it seems to be starting and running very well with just the new distributor and leads. I did give the position and speed connectors a wiggle to check they were connected OK. Its also cleared up the misfire it'd had previously too.

 

[robwright]

Does it have an immobiliser?? The 12V supply to the DME is usually a good candidate for one of the two required immobiliser circuits. If that circuit in the immobiliser was failing it would crank and not start as you described.

 

[dave364634]

yep.

the dme is what?

ta.

 

[robwright]

The engine management computer. Runs all the fuel injection and spark mate. It's just a thought. It could be a few things. It could be the DME relay, which both powers up the DME and runs the fuel pump.

 

[pauljmcnulty]

the dme is what?

Most 944 owners carry a spare DME relay. Less than £20, and if you've not changed it for a new one you're on borrowed time. If you have replaced it, then cary a spare anyway.

 

[dave364634]

where is the dme relay then? in the fuse box under the bonnet?

thanks.

 

[robwright]

Yep in the fusebox with the rest of them mate.

 

[alwigley]

Have you been having problems with the idele speed - either too high or too low, perhaps affected by engine and/or external temperature ? Could well be a sensor failing giving intermittent readings - first point of call might be the DME temp sensor - unplug it with the engine running and see if anything changes........ There is a very good section in the workshop manual covering troubleshooting of the Motronic system, which gives details of how to test many of the other main components.