Zero10

They're pretty pricey, at least compared to a 924 =)
I believe they are around $50-60 US each. Usually when they leak though, they can be fixed for much less than replacing them. Usually it's them being gummed up.

I thought about it being detonation, and although it does seem like a long shot, it almost seems possible. If you are relating it to your drag racing car, where it almost definately was detonation.... well?
I don't quite know what to make of it. On carbeurated cars, it is strangely common. I remember my subaru.... that thing could run quite some time with the key off. But I know it wasn't detonating.

In my head, there should be no fuel and no spark as soon as the key is off. When it is in a condition where it would normally diesel (I don't know exactly when it does it) what happens if you turn the key off really quick and pull it out?

When I read 85 1/2, I presume that means early 85 (correct me if I am wrong), but the early's had a couple circuits come on when the key was inserted. Although it doesn't make much sense, but if things got worn out, I could almost imagine it keeping either the coil or the injectors on for a short time (although they are DME controlled).

I guess the other possibility is the DME itself? But that seems as remote as the detonation.
Sorry I don't know how to troubleshoot this one too well. If the car was right in front of me I am sure I could think up a couple tests, but it's harder to do over this board.
I'm just hoping that something I throw out there leads you in the right direction. You don't have to go check every single thing I list.

Back to URIN 2ND
I was just typing the way I talk. The umm was thinking, not trying to be condescending, and the sorry was because I realized that it could be read that way. I was not trying to insult your intelligence. I hope you're not calling me a forum troll. I make an honest attempt to help people out, even though I'm not a member.
I was not trying to offend you, and I certainly wish I had not. So, I'll turn this into a formal apology, and hope we can continue a friendly relationship on this board. Although, I don't think I'll make another post in that format, since I now know it can be taken the wrong way.

Hope to see you continue posting here.

rwodabek

This might be a little off the wall, but what about the grade of fuel? I am of the understanding that with my 968 if I put in anything under 93 octane there could be run-on.

HTH

Richard.

AWolf

I am using premium in the car and it is a late 1985 model. In doing a search on my same problem I noticed the majority of the people who were complaining about Run-on had 85.5's. Just a coincidence maybe.
-Andrew

Dal Heger

It doesn't have anything to do with the ignition system, that is shut down as soon as the DME is turned off, as soon as the key is turned to the off position. It's a digital system, it's either on or off, this is also true with the fuel injectors. It is most likely that one or more of your injectors is leaking. This would let your cars diesel on turn off.

I'd take the fuel injectors out, and find a local diesel rebuilding shop. They usually have the experience and tools to rebuild/clean the inhectors, it usually costs about $25/injector. Get them to give you a few extra rubber o-rings for the off chance that you'll pinch an o-ring putting the injectors back in the fuel rail (BTDT). Use a little bit of white grease to coat the o-rings to slid in easily.

The only other chance is that the electrical part of your ignition switch is worn out and is keeping contact when you turn the key off (not likely, but possible). Usually when the switch fails it'll fail in the "off" position, not letting you start the car, or keep it running.

Good luck.

Dal.

L8 APEKS

No worries mate, thanks for explaining.

I just bought my first 944 so I am trying to learn the motor...I'll be in for a crash course in a couple of weeks, though, since I have a complete rebuild to do on the S I just bought. lol.

Redlyne_mr2

It's a common 944 problem. Unfortunately I dont remember the exact name to the part that fails but its a small diode that fails. Its a super easy job, I would contact your nearest porsche repair shop, they should know immediately what it is. It's a $20 part in CND funds and take less than an hour to install. So even if you pay a shop to do it, its worth the 80-100 bucks. Apparently there are no adverse affects due to the dieseling, its just a Pain to deal with.

Zero10

Really? I was feeling pretty certain it was a leaky injector.
Redlyne_mr2, was this an issue on your 944, or have you seen this problem before?

I could imagine it being an electrical issue, perhaps inside the DME itself, I just always thought that power was cut to anything that could keep the car running, via the ignition switch.

Dal:
I believe you are right about the ignition switch, 99% of the time they fail 'off', so they won't let you start the car.

URIN 2ND, I'm going to presume the no worries part was for me, and I'm going to keep on smiling =)

SoCal Driver

Pull off the fuel rail, lay it back on top of the engine on some rags.

Jump the DME relay socket to run the fuel pump for just a few seconds to pressurize the system.

Check the ends of the injectors for leaks.

Replace the leaking injector.

An engine can not diesel with out fuel.


Sean, When was the last time the cam chain tensioner was checked on your 944?

Zero10

Oh, time to throw a question in here.
What holds the fuel injectors onto the rail? Those little metal clips?
Does anybody have a picture of how they install into the injectors/rail? Mine don't look like they will fit in any direction. Perhaps the injectors are not fully seated into the fuel rail.

If they do not hold them in, isn't there a risk of an injector popping out if you preform that test?