I was refering to the physical condition of the 4 metal points inside the cap and the rotor arm making contact and not the condition of the wires going to the cap.

The description of your recent post about the car stalling is a more specific. I know it sounds weird, this is the exact symptom of a disconnected AFM. In the original post, I thought you had a slow stumble to stall and if you open the throttle it will continue to run smoothly if its above 3000 RPM (which is not possible with a disconnected AFM).

I am not sure what caused your backfiring in the first place after the things you checked since you have check the spark plug wires, cap/rotor, cam timing, and compression. Lets see if we can figure out whether this is a fuel/air related issue. Use a can of starting fluid, have someone squirt it into the intake in short pulses like an injector after you start the car. If it runs smoothly, then we can be certain the problem is in the fuel or intake system. If the problem persists, then its in the ignition or electronic system. Give me a try and lets see what happens.

The throttle valve vacuum lines are connected in the right spot.

http://forums.pelicanparts.com/showthread.php?s=&threadid=79411&perpage=20&highli ght=dme%20plug%20diagram&pagenumber=1

What about this? The description sounds very similar. Could I have a bad DME?

Where is the DME relay located? 1983.



I am running out of paitence on this. I have 24 hours into trouble shooting this problem right now.

Speedy:(

i am going to make run into town and get some starting fluid....

I can understand the frustration as I have run into a few 944s with stubborn problems where I feel like using my 18 pound sledge hammer. A bad DME normally is caused by bad soldering joints. However, its a big coincidence for a DME to go bad right after working on the car. The starting fluid should not make the car run better if the problem is in the electronics.

A DME relay is located under the dash on the driver side behind above the fuses. On the early car, it only controls the fuel relay if memory serves correct.

The computer is under the dash on the passenger side. DME relay is on the panel, do not confuse the 2, the relay is the fuel relay, the DME is the brain. Being it is an 83 I would open the DME to check the connections on the "grey" ribbon to the board. This is a common issue on the early 944. I missed this earlier. I was thinking late model 944.

Dal

I shot some short bursts of starting fluid in the intake upstream from the AFM and the engine would rev but ping pretty bad for about 2 revolutions.

I was able to nurse the engine to run by blipping the throttle until it was warmed up. It started to idle a bit better and wouldn't stall but it would still pop and sputter. while it was idleing I pulled the vacuum lines off of the fuel pressure regulator and dampener and that seemed to smooth out the idle and raise it to about 1200 RPM. At this time the car was warm enough to have the cooling fans kick on and off. I -shut it down and tried to duplicate the smooth idle I just got but I couldn't get it to do it again.



I will try to open the DME and check the gray ribbon. Is the cover just attached by screws?


Thanks for everybodies help so far.


Speedy:)

The square silver box embossed Motronic. On the bottom sides there are tabs. Very gently!! peel them back to allow the cover to release. Those tabs are very EZ to snap so be very slow at bending them and only far enough to clear. You will understand once you look at it. Once inside be careful and you will see a few black plastic pins connecting one board to the base/board. The trick to the pins is they pull up by the use of a small screw driver(jewelers) inserted. If I recall. But just be deliberate when attempting to pull apart. You will see the solder points of the ribbon(many). If they look rusted out or tarnished you may have your issue.

Dal

On the 83, the DME and the DME relay are under the DRIVER side. The DME is directly under the steering column and the relay is above the fuses. The best way to check the DME is to borrow one from a friend and switch them around and use your dme in the other car. If it runs well in the other car, its not your DME.

BTW, when you pulled the vacuum line, do you see fuel coming out from the vacuum line end of the regulator? If you do, the diaphram is bad on the fuel regulator, which can flood the engine, cause no starts, and run very rich when it runs.

Ah my bad, thought 944's had them on the passenger side.

Dal

The 85.5 and later 944s do have it on the passenger side. I just wanted to make sure he is not digging under the carpet not finding the DME to add to his frustrations.

So true! But heck if I can chase down an issue for a year so can he!! j/k:)

Dal

No fuel leaking from the lines or the regulator / dampener.

The regulator and dampener are 2 years old.

Speedy:)

Sure sounds like the problem that I was having, DME eventually was the culprit.

Does anybody have an early (pre 85.5) DME I may rent/ borrow for a short time to test on my car.


Speedy:)

The DME which many944s let me try did not solve the no run issue. (Thanks once again many944s) I am going to take another look at the fuel more specifically the fuel pump by checking the flow rate. The car has not moved for about a month now. :(

It needs to get fixed and driven.

Speedy:)

Have you checked the fuel pump/DME relay?

I swapped it out with the one in the "s" and there was no change. I was going to jump the DME relay anyways to get the pump to turn on and flow.

The S relay and the '83 relay had the same pin assignments and functions so I assumed it would work. I will find out if my assumption was correct when I jumper it.

Speedy:)

It just hit me like a sledgehammer that it could be the DME relay. I'd hate for you to get into the fuel pump and it turns out to be another dead end.

Also try changing the fuel filter.

I have a new fuel filter in my shop. It will get installed.

I will work on the car on Friday and try to nail down the problem

Speedy:)

Speedy, I just re-read this whole post. Are you SURE your rotor is not loose? Incorrect timing can sure cause a backfire. Ask CJFusco how quickly it can change from good to bad. EDIT: Found it here:

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/246189-started-died-no-start-backfire.html?highlight=rotor