No injector pulse

[stick1975]

I jumped the AFC relay and that voltage drop at the injector connector. I called 928Int. yesterday. I talked to Jim. He was real helpful. I told him about the injector pulse problem and I told him about how it would not spin with the key, no mater where the shifter is. I ordered a new AFC relay, a new ing. switch, and a wire he said goes bad that is connected to the switch. I'm really not trying to just throw money at it by replacing parts, but it can't hurt to replace 20 year old elc. parts. I think I need to do like Landseer and take EC panel down and take the pod apart where the ing. switch is and just do power and ground checks on every thing. Is it hard to take that pod apart without breaking a bunch of stuff? Danglerb, so the distributor is hooked to the spark box, then the spark box sends a signal to the computer? And it will still fire the coil if the green wire is bad? Think I'll order a green wire from 928int. too...

[Danglerb]

Check the green wire, if it looks nice, maybe try something else first, but if it looks original, start with it. Save the old connectors as you "might" be able to rebuild the cable.

[stick1975]

Going to take your advise from a few days ago Danglerb. Called 928Int. and also ordered a "green wire". Over the holidays I'm gona try and R&R my ing switch, AFC relay, and the green wire. I should probable just change one part at a time, so I know what was actually wrong, but everything is 20 plus years old, so it can't hurt can it? It's very frustrating. Wish I could find "Trouble Trees" like old GM service manuals have. "Check ECU terminal 16, Batt. voltage, go step 6, no voltage go to step 3". Wish I could find info like that. Hard to diagnose something when you don't know how it works. It has to be some kind of "batch fire" injection. One bank of injectors fires every other turn of the crank. But does the computer get that info from the dis, or the Ing box? Is one wire to each injector suppose to have batt. voltage on it with the key on? I really do appreciate all the replies I have gotten though. Thank all of you.

[Landseer]

You likely are on the right path now, I think! Take you time, replace the parts. Looking forward to your posts and success on this.

[Danglerb]

The two banks of injectors are internally wired to the same point. All are in parallel and fire at the same time.

The manuals do have "some" trouble shooting sections, but nothing like the manuals for Ford etc. JDSporsche.com may have some more info, but frankly if we don't talk about it once a week on one of the forums it likely isn't a trouble area.

Porsche didn't plan this car around fixing items as they break, or enough of them break to cause a problem. Porsche expected the cars to be SERVICED replacing parts well ahead of failure. Spooky to think what that would cost.

[Landseer]

Here, on the pinout for the L-Jet, I went to Rennlist and did a very quick search ----
http://forums.rennlist.com/rennforums/928-forum/153396-l-jetronic-connector-pin-out.html

one of dozens of discussion threads ---
http://forums.rennlist.com/rennforums/928-forum/40432-help-trouble-shooting-l-jet.html

In my experience if you just search and read for a few days you will find all the data you need, then you can post your solution back here to this board for the rest of us.

There is a Bosch Fuel Injection manual that you can buy that covers L-Jet for most cars (there were many) that used it. Its author is Probst I think.

I think you will find it if you search the net.
Here's a primer that helped me:
http://www.hiperformancestore.com/Ljetronic.htm

This helps explain the sensors, though the C sensor is replaced by the green wire system in our cars.
http://www.international-auto.com/index.cfm?fa=ad&aid=9

There is also a concise 928 Service booklet on the L-Jet system with troubleshooting trees, pictures and various test values, I think its within the CD set. I have a zipped protected version of it. Will try to find a public source for you.