Mike C.

I've seen a few non-Porsche 4 cylinders run on 3; not well but still started and ran (try it by pulling a plug wire). A friend had Honda in which one cylinder had 0 (as in 0.0) on the comp gauge and still ran. I don't see why a 944 would be any different. I can't imagine you have any bent valves if the timing belt/mark still line up. How does the antifreeze and oil look? A bad head gasket could certainly cause problems but to prevent firing of any cylinder still seems a stretch. My understanding of the DME is that if you don't have at least the flywheel sensors and air flow meter (maybe a few others), the DME will not turn on the fuel pump relay. So if you are getting spark and fuel... My money is on low fuel pressure at this point.

Mark944na86

I know you've already verified spark, but are you sure you are getting a spark on all 4 cylinders?

And if you haven't had a look already, it would be worthwhile to remove your distributor cap to inspect state of cap and rotor. You could also try cranking it when it dark to see if get a lightshow of HT arcing -- old cap, wires etc. can lead to that. If the juice isn't getting to the end of the plug, the cylinder's not firing...

rgs944

After this is figured out it will be a great "no start" thread in the search to help future rennlisters. I know I am learning stuff as we go. I just hope one of these first days Roman will make the post that the damn thing started up and tell us what was wrong. I feel like I am reading a murder mystery.

Mark944na86

Oh, and nothing to do with troubleshooting the no-start, but when you do get it running, you may want to change your oil right away. All this cranking with no start would be washing a lot of fuel into your oil.

roman944

Jim - I am going to be at work until about 4pm, but my brother and my dad will be at home, so I'm going to let them know that you will be here tomorrow

there should be a car here in case a jump will be needed, though, probably won't have to jump it

Mike - at this point, I'll take that guess, you and me both

roman944

Mark - new cap and rotor (only driven on them for 2 months now), I doubt they would wear out in 2 months of light use? I still have old ones though, so may be worth a shot mixing and matching the 2

you may be right on oil, this was a fresh oil change, I probably have 1500 miles total on it though, Redline 20w-50 ... and no, I don't think that this is a reason why my car does not crank, as I have driven it in COLD days before and it always started and ran great

shiners780

Have BFH, will travel.

roman944

Jim, all goes well, I will OWE you !!!!!!!!!!!

roman944

Jim stopped by and we did a compression check

I wasn't here when it was done though

#'s are 150 on 1-3 and 125 (or so) on #4

not great, but not bad either

Jim said that they couldn't find spark ... I got my new Bosch +4 plugs today - we were putting them in, and checking for spark after replacing them 1 by 1 - and we got spark - I saw it - on all 4 cylinders

new FPR came in as well, so we put that in as well

waiting for battery to charge up - and going to see if the car will start or not

really looking for more input on the next steps

Mark944na86

It might be getting time to try swapping in a known good DME. If it is the DME, fortunately they can be had for little money these days. You might even consider buying a spare just to assist in troubleshooting further down the line.

The other possibility is the DME is OK, but isn't getting a sensor input for some reason. Reference sensor sounds fine, but what about TPS, for example? I'm not sure if that would cause a no start condition, though... perhaps someone else can say. You can check the TPS itself fairly straightforwardly with a multimeter, then you'd have to check connectivity back to the DME.

Mark944na86

The other thing that occurs is that if there is some ambiguity about spark, perhaps the spark is there, but weak? New coil needed? Just throwing out some thoughts here...

roman944

good ideas Mark - I was thinking about that too; I have new cap + rotor + plugs, but we didn't change wires or coil because they appeared to be in good shape

overnight we are charging the battery

and I was wondering the same thing about the DME - I replaced the DME I had in the car with a brand new unit - and still no start; I made a Y-jumper, heard the fuel pump, but car didn't start

shiners780

I think Mark is referring to the DME computer, not the DME relay. Have you had the DME computer out for any reason lately? I didn't have my car with me or I would have swapped them to test.

Your brother told me about the symptoms you had before the car died, sounded very much like the TPS...hunting idle, hesitation on throttle, etc. I didn't have the test specifics with me (which terminals to test on the DME harness) so you might want to check that out. Clarks has a writeup on that.

I think you have an electrical problem. I checked all 4 ignition wires and the coil wire and none had spark. To verify, I had your Dad check while I cranked and he saw no spark either. I used a screwdriver, he used a spark plug. If it had a weak spark, then it's pretty damn weak, because I was looking very closely and there was nothing. It's not a complicated procedure. Now it has spark? Something is funky here.

Mark944na86

Yes -- didn't realise there was some ambiguity there.

Mark944na86

I think you are getting close to figuring this out.

EDIT: Could the battery charge difference account for the discrepancy? If spark or no spark depends on battery charge condition, I'd replace the coil as the next step. (Or at least test by swapping in a known good one.)