SOLVED 944S Start up trouble after rebuild
 

I have an 87 944S that I just rebuilt the head on and after a year of rebuild and fixing I finally started the car this saturday.
It ran great, with a little lifter noise (all brand new VW 16V lifters).

I took the car for a drive and it ran smooth.

I took the car for a wash, in a machine because i just wanted it clean it off before i did a hand wash and wax the next day. But it was after this that the trouble started.

When i parked the car in my garage right after, and turn off the ignition, the engine stopped, but the starter kept turning and turning. And a turning the key all the way to the right resulted in the car roaring back to life. I could not manage to turn it off! I popped the hood and found there to be a lof of soap foam around the battery and the fuse box, which I cleand up. The car still didnt want to turn off. So i decided to try and disconnect the battery, but I didn't have a wrench that fit so it proved difficult.
Then, suddenly I heard what sounded like someone dropping or hitting metal, and the engine sound changed slightly. So I tired to turn it off, and it did.

I decided to leave the car off and deal with it the following day, which I didn't. I returned on Monday to look at it, changed the starter with another one that was working, tried to start the car but nonthing. Turned out the battery was almost completely drained, then it died (this was a brand new battery, only 2-3 days old).
I took the battery from my other NA 944 and installed it.
Now the car has power and the starter works, it cranks and cranks but there is no igintion. Nothing happens.

Anyone had any similar issues? Or any idea of what it could be or what to look for? Would really appreciate this. Have been looking forward to driving this car for the past year.

Thanks!

marius

Starter sat for too long, then also got wet. Obviously an electrical short telling the starter to spin and or extend the Starter gear into the starter ring on the pressure plate. Starters don't like to turn for a long time. If your starter was still extended and spinning and then you turned the engine off you might have broken teeth. Your starter might have seized finally and then possibly could have broken teeth off the starter ring?
When you say it cranks and cranks, is the engine turning or just the starter?

Sounds like the eningne turns but it doesnt fire up. I turned the engine by hand and didnt see any broken or missing teeth on the starter ring.

Holy ****! Man what a story! I think that the starter motor was stuck in an engaged state. The metal sound might have been the starter motor finnally disengaging.

So now you got her cranking again...fuel, spark, compression...?

Rick

yeah, it was quite the day and the day after hehe. There appears to be no spark, but I have yet to check that, i am also checking to see if i can hear the fuel pump start up.

I belive the metal sound was the starter disengaging too.

starter solinoid might be toast from being engauged that long.

yeah the starter that was in the car at the time is completely dead. I put in a new starter and it cranks the engine but doesnt fire up.

If the starter damaged any teeth on the ring gear or the starter itself, the metal particles may be sticking to the crank sensor and causing not to "see" the rotation of the flywheel. If it doesn't sense rotation, you won't get spark....

Thanks Rod, I'll look into that. No teeth on the flyweel appeared to have been damaged. I assume I can just pull the two crank sensors to check for metal particles?

Yes, they *should* pull out of the bracket. Be careful not to loosen the bracket or you'll have to reset the clearance between the sensors and the flywheel. See Clark's garage for more info if needed.

Wait! Does the tachometer bounce?

Thanks, will pull them up, and not move the bracket.
Rick, I'll check that later today but if I recall correctly the gauges seemed to function correctly.

I'd leave the One Crank sensor you have and see if the solinoid blew your DME relay. Remove the relays cover and with someone turning the car over, manually make the 2 contacts touch.

The DME relay is good, I swapped it with the relay from my other running 944.

I did some more testing today, tested the coil, it gives the same readings as the running car, but there is no spark.

I can also not hear the fuel pump running, and disconnected the fuel line into the rail and it was not pumping gas when the ignition is turned.



*By the way, this car has the alarm system but i dont have the key

If you open the DME relay, the top contact touching with the key in the 2nd ignition position, you should hear your fuel pump running. If you just touch the lower contact it sends the signal to the ignition.
Power starts at the battery,
then goes to the ignition switch,
then to the Alarm system,
next to the relay,
DME, (sends signal for spark)
then back to the relay to run the pump.
If you have power to the coil, then maybe the coil bad? Checked all your fuses? Blown ignition module?

but would a bad coil stop the fuel pump from engaging?
The DME relays is good, no problems with it because I took it off my running 944 and im using the one from the stalled car in the running car now.
I'm measuring the voltage on te coil today again to make sure it gets the power it needs.
If the alarm system was failing, would the car crank? Would it crank but not send signal to fuel pump and spark?
How can i check the ignition module? This is the one that's in the driver side by the fender? Or by the headlight? I've read both.

Thanks

There's 12v on the coil measurring the + side of the coil to the engine or the - on the battery.
Checked the inition module in the headlight bay. There's 12v coming across on the plut going into it. How do I check to see if the module is blown?
All the fuses are good.

I sometimes use the DME relay to direct me to general area of trouble. You manually make the contacts touch. See other response. I had a "professional" Porsche mechanic change 8 years ago, relay and modules with "Known" to work parts, charged me $700, without fixing the car. It was the ignition module the whole time. I'm not sure how to check it, but I would imagine if you have volts to the coil its working. Maybe no fuel.

Dan, I'll try connecting the DME with the top contact only, to start the pump. The coil has power and there's power in the plug that goes to the ignition control unit (module). But guess there's no way of testing that? If the ICU is gone, would that make the pump not start up?
I filled it up with fuel the day before.

Update.

I tested the fuel pump/dme relay as per the manual by connecting a test lead between two pins on the DME plug, and the fuel pump didn't engange with the ignition on.

I also tried to jump the dme relay with a 3-way wire on 87, 87b and 30 and this did not engange the fuel pump either with the ignition on, and when I tired to start it, it just kept cranking as usual.

What to look for after this? Any ideas anyone?

Thanks!

This is a list I started a while ago something here may help narrow it down.
Hmmmm.... that could be alot! you really have to go step by step and check the ecu harness and voltages to each area as you go. Here is a list of some test you should do one by one and eliminate problems.
Air/fuel/spark/compression
start by making sure we have a battery that is in spec.
all fluids topped off
no obvious broken wires and all vaccum hoses intact on visual inspection.
OK we have 12v at the battery with adequated cranking voltage we get in and turn the key.
12v from battery to ignition switch
12v from pin 50 on switch to pin 4 on dme plug (start signal)
12v on pins 1 (ignition pulse to ign. coil) and 18 (to G5 dme relay power supply)
12v pin 30 at dme relay (fuel pump power supply)
12v to pin 86 at dme relay in the run position (primary coil voltage)
12v to coil + black wire to ground 12v to - (green wire) to ground
12v to one side of the injectors
All ground contacts are clean
Fuel pump will run if dme relay is jumpered 30/87/87b
Fuel pressure at the rail is 29psig +/- 3 (jumpered 36 psig)
20 minute leakdown not under 14.5 psig
Fuel flow rate is 28oz after 30 seconds
Ignition coil primary resistance across + and - is between .4 and .6 ohms
Secondary resistance is between 5000 and 7200 ohms
Ignition wires are good no cracks or splits including coil wire and seated
Plugs are properly gapped
Ignition rotor is seated correctly with the set screw
Timing belt is installed correctly
Firing order is correct
Reference sensors are gapped correctly with .8mm clearance off the flywheel
Reference and speed sensors resistance checks in spec pins 8 and 27 speed 600-1600 ohms and pins 8 and 23 >1m ohm
Reference and speed sensors voltage checks 2.5 and 2v on oscilliscope (good luck)
Reference and speed sensor wiring is not broken at connector to sensor or to dme
Ok Im tired anyone else want to add or be more specific?

And I checked terminal 30 (for the dme relay) with a spade plug into it with the red wire on the volt meter and the black on the - battery and it came up with 11.86 volts, so close enough i think. So at least the DME relay has power...

I went under to change my fuel filter, gotta change that anyway, and I also looked at the pump. I disconnected the green wire on the pump and used a test lead from + on battery to the fuel pump where the green goes, no action.
I disconnected the brown wire and used my volt meter, with the battery to the car connected, and check the two wires with the ignition in "on", all the way to the right, before it cranks, and i got no reading at all. Will it only show a reading when the car cranks? Or should it still show voltage?

When you jumper 12 vdc to the fuel pump (green wire) it should run.

It should right? I pulled the green wire off the pump and then put the 12V lead from the battery (out of the car) directly onto the pump.

If, for some reason the pump is bad, would that cause all these issues? like no spark etc?

A bad fuel pump will not cause no spark.

Update on this nightmare, the fuel pump is good, works when i put 12v straight to it.

I tried test point 15 on page 136 of the 16V manual.
I connected a test lead with a spade on each end to the two pins it says. But nothing happened. Then i turned the key to "on", still nothing. I tried Cranking the engine and i heard the fuel pump start for a short burst, but then everything went dead. The clock went dead, the engine didn't crank either. And i think i took the key out, and put it back in but still nothing. Then I disconnected the battery and connected it again and the clock, lights etc started working again and the car cranks.

I quickly read through this, but have you checked fuses?

If so sorry i missed it.

Possibility that the ground cable from bell housing to block gave out or body to block?

Maybe that's why the starter didn't want to work?

checked all the fuses, all good, all relays are good too.

There might something about a ground, but i changed the starter and the starter works.

This all happened after driving through a car wash. The car was running before this. Turned it off in the car wash, started right up after, drove about 2 minutes tops to my house, then parked and tried to turn the car off. The engine turned off but the starter was still engaged. It went like that for maybe 5-8 minutes, then a semi loud metallic clank and the engine sound changed. I assume the clank was the starter disengaging and the engine sound changing being that the starter was no longer running.
The battery was dead the next day, starter was dead. Replaced battery, replaced starter and now it only cranks.

I ended up towing it to a shop, G-Man Automotive in Culver City. He diagnosed it and got it running.

The Ignition Module was dead, I had tried with a new module but never heat sinked it to the fender so it didnt get grounded and thus didnt work.

Also he said the white relay (i only spoke to him on the phone so not sure which relay he refers to) was also dead.

So now the car runs! Lesson learned, always pull and install Ignition Module with heat sink even if the old one might still be good (which it wasn't in this case).