Ok guys, I need some advice and help here. My '88 is stranded in Georgia. I drove it home over the xmas holiday and, after buying some oil at Advance auto parts, the car refused to start. I checked and the car was getting fuel but no spark. So, I bought a brand new DME from Auto Atlanta (open on xmas eve and quite a place to visit I might add!) and that did nothing. When I got home to Richmond, I sent back a new (ish) brain from a friend, one that we knew was working. Nada. Nothing. Car is still getting no spark. So what I have read on here (yes, I actually searched before posting this!) was that it could be a stuck reference sensor. My question to you guys is this: does anyone have a picture of said sensors so that I might send them to my buddy who is working on the car for me? Since I am unable to convey where the sensors are to my buddy via phone, I would like to be more specific with him so he can give them a whack and see if it frees them up. Also, any more advice on what I might try? Could the coil have gone bad? It's unthinkable to me that a coil would cease to function, but my car DOES have 150k on it...

Thanks for the input guys. I'm having to drive my wife's (yes, I got married last saturday...my second time and last.) Z3M which, while not so bad, is no 944...

 

Here is a picture of the reference sensors from Clarks Garage. They are located at the back of the engine above the bell housing.

 

Hitting the sensor will not do anything, there is no moving parts in them. Measuring the resistance of the coil inside of them or looking at the output with a scope is the way to test the sensors. Check that the connectors are not falling apart, real common problem. Another thing to check is that the bottom of the sensors are clean of metal shavings. they have a magnet inside of them but I doubt this is your problem. When installing the sensors, the correct gap is very importent to avoid damage and for proper operation.

You can also force a spark out of the coil by tapping the coil terminal that goes to the DME (negitive lead) to ground with the ignition on. I would check this first, also make sure +12V is on the positive terminal of the coil.

 

You just bought some oil......or you changed the oil?
If you changed the oil and filter, you might have loosened the coil wire to the dist cap?

 

Same thing happens to me... I wiggle the referance sensor wires and it fires right up...132k 87 turbo...Yep I have brand new sensors I need to replace the referance sensor harness..LR has them for sale.. I have replaced them on Car number 2 not hard to do .


-BB

 

Just an FYI, if you're going to buy two new sensors, make sure you get the cheaper ones. The ones meant for the BMW (forget which model) are $79 dollars each instead of $150+ each. The only difference between them is they have a slightly longer wire.

You can get them from 944online.com as well as Pelican Parts.

 

Hey Colin,

Great name! Thanks for the pic... I didnt realize they were so visible. That helps!

And no, I had not changed the oil. The oil needed changing and I had stopped at Advance to get some.

 

I would add that the DME relay may have failed. This not uncommon and many people carry a spare. They are about $25 and fit other Porsches as well. You can rig up a jumper to bypass this (Clark's Garage again has the proceedure). This switches on the DME and fuel pump and if one or both contacts don't close you are not going anywhere.

 

I noted that in the original post Quinn. I bought a brand new DME and had a spare that I carry...none of the three (original included) would make the car fire.

I also realize that the reference sensors need to be wiggled or shaken, mostly in hope that the magnet has become stuck. My friend will be trying that tonight thanks to the fantastic picture from Colin.

 

Also, check where the ref/speed sensors couple- my PO broke the linkage (right at the top back of the engine) and they would become loose after driving.

 

Sorry. When you said you bought a new DME, I thought you meant the computer itself. The relay is a different component. I had a lack of spark problem and it turned out to be the DME computer. 20 years of vibration cracked a solder joint. There is a large transistor that fires the coil impulse and that is often the culprit. It is fairly easy to reflow the solder, but it may be more challenging if your car is in another state.

 

Oh!! Well, I DID try a new brain as well. I shipped a working brain to my friend from Richmond and it did not help. We are talking about the brain, right? In the passenger footwell?

 

there is a DME, and a DME relay! I can't understand if you have changed both the computer and the dme relay or just the DME itself. Also dont rule out something simple like a bad coil or something ignition related.

 

DME relay- BUY A NEW one, ~20 bucks for the dealer, I carry a spare in the glove box.
If you tap (rather hard ) the DME while starting, suspect a cold soldr in the DME.
If the tach DOESNT bounce while cranking, check the speed/ ref sensors.

HTH.

 

I changed BOTH. And as far as the coil goes, that is about the only thing that hasnt been changed or checked...