Porsche Enthusiasts Club Forum

Finally I get to enjoy the real buzz of 944 ownership, damn thing won't start so guess that makes me a fully fledged club member now

I've got no spark, fitted new plugs, leads, dizzy, rotor arm t'other week, not gone as far as the coil yet.
New DME relay, I've swapped that over for the old one to check just incase the new one had failed for some daft reason.

The rev counter doesn't bounce when I turn the engine over, going back over a few previous posts Jim suggests dme or crank sensors in this situation. Knowing the dme is OK is this just a case of go straight to the crank sensor or could there be any other possible causes to check 1st.

Cheers

Think it easiest to start with the crank sensors. Mine play up and I've got it down to a fine art taking them out.

note to self. Must replace ASAP

I changed the crank sensors on mine, quite an easy straightforward job to do, they must be quite troublesome as the previous owner had had only done them 3 years earlier on mine.

Mine were seized solid when I tried to swap them with Pauls for testing!

Check the DME has 12V on it. Can''t remember the pin no's but it is in the on-line manual, but not in my written one
If that is OK then it could be alarm module as posted a week or so ago here or the sensors.

Cheers guys, will grab a multi meter and check the feed for the dme then go to the sensors if that's OK.

Can the sensors be cleaned or something then seeing as you've pulled your's out a few times? I'm slowly working through bits like that in a prevention rather than cure when it does go kaput, guess these might have beat me too it though.

I don't really know whats wrong with them. When the car won't start, thats the first place I go. All I have to do is unscrew and remove either. put it back in and it will start first time
Trouble was it went at the beginning of summer and was quickly followed by a trapped nerve in my back. Haven't been out in the car since

I wouldn't be too hasty to pull the crank sensor just yet.
Its onlt a bar magnet with a coil of wire around it. Nothing much to go wrong with that.
Its more likely to be brittle wires due to the heat and age or oxidised terminals in the sensor connectors. Check the sensor first with a multimeter at the first connector which is in a bracket above the cam cover . If its open circuit its had it . The resistance should be as per clarks guide here.
http://www.clarks-garage.com/pdf-manual/ign-02.pdf

Clean the connector terminals and try cranking for a tach bounce. Its a very tiny bounce of the needle easily missed.

Next check the voltage on terminal 30 of the DME relay socket. It should be constantly live 12v+ even with the ignition off.

You have clearly got a fuel supply so I would look at the ignition amplifier first. It amplifies the pulse from the ECU .

Try substituting the DME relay with a 3x way bypass cable. Easy to make with 3x spade connectors and a bit of suitable wire like some 30 amp electrical cable.
Connect terminals 87 & 87b first then connect to terminal 30 (12v+) this should give you a continuously running fuel pump and a supply to the ECU . Try starting . If no start check for voltage at the ignition amplifier.

Thanks for that info Peanut, the speed sensor isn't giving a reading on the multimeter so think that solves my problem will hopefully update shortly to confirm once I've changed that over.

Sorry for the delay in replying been busy this end with other stuff and only just got round to popping the bonnet just wanted to pop on and let you know I'm back on the case and not just grabbing info and vanishing without a thanks for the help till the next problem comes along

no worries. good luck. Once you have a tach bounce on cranking you should get a spark and fuel pressure. Make sure you have 12v+ on terminal 30 of the DME socket and if you use the 3x way bypass you'll get continuous fuel pumping and hopefully it will start.

She's alive

Replacement speed sensor arrived this morning and the grin factor is back.

Thanks for your help once again guys

excellent news

yet another crank sensor fault. When they play up they often give intermittant no start /poor running which is a pitta to track down.
Think i'll order a new one myself .

Cheapest place I found is ZimmTechnik in the US they are around $109

thanks Jim... the're not cheap are they

Do you have a weblink for that company Jim, Googled the name but nothing came up.

They're stupidly expensive for what looks to be no more than a bit of wire with a metalic plug on the end, there must be more to them inside.

I'm guessing with one of mine failing the other won't be too far behind, thinking on trying to find a used one just to stick in the toolbox to save possibly being stranded out somewhere.

Try http://www.allzim.com/

Ask for Kirk Pruitt & tell him Jim Hearnden from TIPEC sent you, he may give you a bit of TIPEC discount IF you are a member. They are in Bedford Texas & I visited whilst in the US a couple of months ago.

I believe a BMW sensor may fit & is slightly cheaper.