JET951

Martin,
Get a screw driver and push the rubber grommet through the firewall. There are slits in the grommet that allow the reference cables to be removed and new ones installed. Once done spray some silicone spray on it and push it back in. Also this is the 944 forum, but we are always happy to help
Regards
Sean

poirsche

Ok I too have a no start conditions and thought I’d add to this thread content for what I hope is an easy fix.
Try to keep it short but here’s the story… first off it would have been impossible to get as far as I did without Rennlist🙌 now I need you Porsche geniuses to assist me get this poor yet worthy 951 back on the road.

86’ 951 / had been sitting in the bushes for more than 10yr. Had a “fuel pump issue”🤣, dry heat, towed it home got it running. Smoked a little at first, had a stabile idle but couldn’t put it on the road as I had no wheels. Wheels were in bad shape and I don’t yet have extra wheels: so I had the wheels redone while I worked on the motor.

Things were obviously in crispy shape and much of the plastic and rubber required replacement, which I did. Including most of the sensors, vacuum lines, coolant hoses, brake lines, ignition coil, plugs, starter cables, battery, solid state DME, fuel lines, injectors & engine bay wire-harness. Fair to say most of the important stuff in the starter system is new, rebuilt or fully serviced & ohm checked for integrity prior to reinstall from the surface at least. I did not rebuilt the head or dive into anything outside of basic part replacement maintenance and refurbishment.

wheels came in, got the new tires mounted. I finish installing the new suspension, bushings, brake lines, brake sensors, rebuilt calipers & rotors. And by this time I pulled the entire exhaust and wire wheeled the sh* out of it, wrapped it all in fiberglass thermal wrap I had and reinstalled most of the exhaust, left everything after the CAT off as I was going to replace the ricer muffler that I found on the end anyways. Car had a little trouble starting once I got the wheels on, but it started up, sounded great until I had a fuel spray from the rail (had some issue getting the rail to press nicely to the head without some convincing with all the new gaskets) but once I got the rail tight everything started and ran, well kinda ran it Miss fired. after the fuel spray I had done some clean up around the rotor after the fuel spray and I must of mixed the coil wires on the rotor.. anxious to DRIVE IT. Any ways she was really rough to start I had to jump the battery to start it up and then I kept the battery on a maintainer. The car didn’t want to run on this last attempt it shuttered, had a very rough idle and then died out. Next attempt the ignition just clicked. No crank.

pulled the starter and had it rebuilt, tested the ignition switch and it had an irregular ohm reading so I ended up replacing it to rule out some obvious possible issues. Starter came back, installed it and tried to turn it over.. but she only whines, and clicks at me. the starter solenoid is doing its job the relays are clicking and lighting up (thanks Ftech9) the plugs are sparking and the motor does not fire. Suspected that something electrical was the matter because the Solid State DME relay post incident, has the “Ctl Fuel” light lit up, even when the keys are in my pocket. So this led me down a rabbit hole trying to check why would the DME continue to power the fuel pump without the ignition on?

As there was suspect that i muddled something in the wire harness repair, I did a resistor & ohm check on everything I could think of.. electrical post checked out, DME & KLR checked out, ref. & speed sensor checked out, coil checked, injectors checked, all the wiring was in its place and there were no shorts identified. At this point nothing improves the motor just whines & clicks when the ignition is engaged, DME light is shining bright. Battery reads 12.7v feeling a little exhausted / stumped.

In checking the ignition & plugs again there was a moment in checking the ignition coil and main lead, I was getting lazy and I had a spark plug setup resting on the intake manifold and it slid to where now the spark plug in the main lead, with it jumped to the terminal ground, touched the intake manifold and my slow whine jumped to a full crank and fire. The spark plugs were in the motor, ignition coils disconnected to the distributor. At this point I am excited, it was the first full fire in days of working on her. However I know that’s not a good setup and I did not want to repeat that only to burn out something else.

Today I did a cold compression test.. which maybe pointless, but I can’t get the motor running and I need to source a leak down tester. The test results were obviously low cold but with all the spark plugs out it turns over productively.
Test results were C. 1-100, 2-90, 3-100, 4-90

Looking for some advice, would love someone to see what I am obviously not looking at.

Thank you in advance -

944M3

Sounds like you’ve looked at all the obvious stuff.

Just a couple of weeks ago I finished putting together my NA after an engine out reseal. Started great and then a few days later just went dead, not even cranking if I recall. First idea was to jump the DME fuel relay. Car started up but was running really rough. I thought maybe it was missing a cylinder, but spark checked out on all plugs (used the light strobe thingy). Then thought bad injector, so I sprayed water on the headers and found number 4 was not steaming. Replaced injector and started right up. Btw it was a newly rebuilt injector and I was using ftech9 relay.

I mention this because it sounds like you did get the car to fire but ran rough.

If you are still using the original DME (computer) that sat for 10 years, I would check that out too. A bad DME can cause funky issues and no real way to troubleshoot them. Sitting for 10 years I would send out to ECU Doctor to be checked out. And even if it ok now and not causing your issue, it’s only a matter of time before it dies. I’ve had 4 die on me before I learned my lesson and have ECU Doctor repair them. Or just get a new one from ftech9. Again, if it’s the original one, it will die eventually.

poirsche

Thanks for that feedback.

you are right to assume the Motoronics box is original. I have a spare KLR but not a motoronics DME box to swap out. Is there a bypass test to check the DME box that anyone knows about?

Don’t need any more excuses to buy stuff for the 951, but I have been scooping out the Ftechs OBD2 DME. Has anyone tried that out?

Thanks will continue to work through it

944M3

Can’t bypass the brain. No real way to troubleshoot unless you know how to work on circuit boards. Open it up and look for signs of corrosion.

Sorry if I missed it, but did you say it ran while bypassing the DME relay? Meaning, if it’s all together and you jumped the relay, does it start and run?

poirsche

No I haven’t tried to bypass the DME in anyway.
the solidstate relay is fully functional and I don’t have a spare motronics DME. LOOKING into replacement, spare or have it refurbished.

944M3

I had the solid state relay installed when I had the bad injector and it still wouldn’t start.

I would suggest to try bypassing the DME fuel relay. It’s easy enough. Plenty of posts on how to do it, but I’ve attached a picture of my setup.

poirsche

thank you for that suggestion, but no cigar.
Looking at DME refurbishment vs New DME. 💸💸💸💸💸💸💸💸💸💸💸💸💸💸💸💸💸💸💸

944M3

Haha you have to be brave with the wallet when owning a 951. I did the exact same thing you are doing now, put a 951 back on the road after sitting for 10 years. So I know your pain. But at least values are going up and still WAY WAY cheaper than owning a Ferrari or any other supercar, so there is that lol

I’m still a little confused on how you got her to fire up and run when you where testing the spark plugs. Did I understand that correctly, you did get the engine running, correct? If so, can you explain a little more on how you did it.

931guru

The best and quickest test for a brain is to install it in a car that runs. If ithe car then does not run, it's the brain.

poirsche

Owned a 951 in 2001, which I also bought from a bush.. Surprisingly more affordable now over other models, so glad the fan fair for this model is still thriving.
Well let me clarify my situation and provide an update. In trying to cure my no-start issue, I was testing the main lead and checking for spark after it ohm tested and volt tested the coil. In my setup the plug at the end of the main lead was jumped to the ground and the plug slid from its position to touch the intake manifold. In doing so, the motor turned over in all four cylinders turning starter to turn over the motor as it should; where prior and currently it does not. when the main lead is connected to the distributor cap, and the spark plugs are in, the motor struggles to turn-over at all when attempting ignition. You just hear the starter whine and turn over the motor very slowly. However In shorting the lead test the motor turned over as it should, cranking at full bore. After testing distributor cap & rotor, then all the spark plug leads and the spark plugs again, they all pass the test generating spark and 12v. So I didn't think it was a spark issue until the short caused a rapid cranking of the motor and starter, which I do not have currently.

Recently, since my last post I went through the Test Plan... again. This time double checking every sensor, its path back to the DME, and double checking the seating in the plug & the connection to the DME box and KLR. My test only checked ohm, voltage and continuity and I didn't have an oscilloscope on hand. One thing I noticed is that when I crank the key to ignition, the volts to the TPS drops. The sensor ohms to spec, the wiring is brand new and it checks out both at the DME plug when ohm testing the sensor and with 5v voltage when key is in ignition position at the plug head, but when I crank the key the voltage does drop to 0, from the plug end. which isnʻt really described in the Test Plan specifically, but it makes me feel like it was the DME box giving me a glitch? I got inconsistent readings in multiple tests coming from the plug ends when the key was at ignition crank position and the DME was plugged in, after every replaceable part in the start system ohm tested in spec, on terminal & at the DME plug, made me rule out the wiring and the sensors. I did try my local Porsche mechanic who did not have any spares and I donʻt know anyone else with this model on island yet. Kinda frustrated, I DID spring for the F9tech replacement Sport DME + OBD considering the reality that this unit may be toast and the OBD feature may be a life saver for all future directions.
But still not the reason why I am not getting a full crank and the motor is fully turning over?

Let me know if you can think of why I am not getting a full crank turn over on the motor when I turn the key to start. Starter is rebuilt, it test great, it is hooked up correctly. Battery volt tests at 12.7v, & ignition switch is new?
I can jump the solenoid on the starter and it cranks the same as when I am turning the key. Basically a slow churn, turning over the motor cylinder at a time.. Any ideas?

Superfx

My 944 left me stranded a couple of times, turned out to be burnt dizzy cap contacts & rotor button arm.
Quick wipe with a file and she ran well again.
But otherwise very very weak or no spark,

944M3

This one is a head scratcher.

Personally my only guess is a bad ground or a bad cable/wire in the wiring harness. But again, that’s a guess.

Look up how to find and clean all grounds if you haven’t already. Easy should take less than hour.

when I replaced my alternator to a Nissan alternator I was having an issue where the alternator was not charging. Replacing the alternator cable harness to the starter fixed the issue. So I’ve seen bad cables do weird things.

Good luck.

poirsche

Thanks! DME is off to Focus9 Going back to square one. Swapping battery, then diving into the starter cable, then connectors, then… you get it. Let you know when I know.

michael2e

Any chance you can swap in another starter to see if that works? I had similar symptonms with slow laborious cranking that I thought was battery related. Pulled off the starter and the ground connection between the solenoid and the starter casing was limited to about 2 microstrands. Perhaps the starter bench tests OK without a load. good luck