Landseer

Have any of you replied or otherwise been inside to repair one?
Tips?
Do John or else Rich rebuild them?

I've been intermittently loosing what appears to be only one bank of injectors in an abrupt, take-you-down-in -traffic electrical malfunction. I truly believe that it is a brain solder joint. Curious if any body else at all has faced this?

Landseer

,,,;

SeanR

I'm going to be going down this path in a couple weeks as a customers car seems to be having issues like this and I have a feeling it's that computer. If I find anything I'll let ya know.

Jeff Bowlsby

L-Jet ECUs are pretty durable, its not likely they fail.

Have you verified the wiring, grounds, and resistor pack?

AN intermittnet problems suggests a wiring connection issue.

hacker-pschorr

Isn't there another L-Jet owner around you can swap brains with to test first?

Landseer

Not sure, got a ride here to VA Beach with all my tools. Have spent hours troubleshooting this, the Stan shaw 84. Traced it to brain, best diagnostics I could. At this point it's running on all 8, but I've got to be at work 8 :30 AM in Elkhart, so gotta call it. At enterprise desk now. It and I will meet again.

John Speake

I don't repair them because I've never been asked to, they so rarely fail. If the problem is intermittent, then most unlikely to be the ECU, go for a wiring issue as has been suggested.

Landseer

Went at the wiring awfully hard. One possibility is failure of ground wire inside a crimp. Or a crimp on one part of the injector harness going bad. But ever under nonstart condition I had continuity across the harness, throughout. To go further, Best approach there will be for me to make up a replacement harness. I have a bunch of jr timing connectors for the injectors. But this car has pretthy solid wiring throughout, not terribly heat soaked..

Am afraid though, like 944 and 951 DME, and 928 cruise brains, that we have something else happening.

John, can you fix them if asked?

More fun to come.

Sean, please share / collaborate on your findings. I didn't meter wires to the exact plan inside the WSM so that is a deficit with my approach.

John Speake

I would have to do a fair amount of work to set up a test rig and then start from zero on tech info. It's just not cost effective for either of us, I would suggest getting a used ECU from 928 International.

Bear in mind that it was only the US 928s that ever used L-Jet, so none in Europe.

Rich9928p

It would be best to plug in a known good L-Jet and see if the problem exists with the other. I've got a loaner if you need it. Send a PM.

I've worked on a few , I'd be willing to take a look at the L-Jet for you.

Good luck,
Rich

'93 928 GTS Covergirl
'87 928 S4
'79 928 5-speed no sunroof rescue
'79 928 track beast

Landseer

Excellent, thank you Rich.

I'll work out a plan tommorrow and connect with you.

joehelendetroit

Was this problem ever resolved? If so, what was the solution?

Landseer

I did not follow up with Rich yet. (Rich is great, he's rebuilt LH / EZK / MAF for me on other car)
Got into a mess of other unexpected stuff at the time I was typing my intended next steps.
Car is 900 miles away.

The morning before leaving, I did find one corroded wire, perhaps to a final stage amplifier, just inside the brain case.
There were two electrical boxes that looked identical, this wire ran to one of them.
Cleaned that bolt-on connection point and reassembled the case. Had a bunch of chalky white oxidation.
Suspect. But not verified. Am hoping that is what "took out" some but not all of the injectors. Makes sense to me if there are indeed two final amplifiers, one for every four injectors. (speculating)

(Didn't know how to remove and inspect the circuit boards, was afraid of breaking something)

Before I left for home, the car it was running agian in the driveway, but no time to road test it.

joejoe

Not sure if applicable, but does the '84 have the ignitors on the front driver side? I believe they are the low impendence for the coil. Or are they for the dual distributor cap as on '85 and newer. If one goes would that cause one bank to fail?

Landseer

For the dual setups.
Does include one style of 84, the ROW aka Euro.
The one giving problems is 84 USA, and I'm speculating that analogous amplifiers live inside the L-Jet brain -- and that I cleaned contacts on one of them- but have not yet tested. Car for reliability.

My local "tester" has another engagement right now in a desert far far away