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I'm not exactly sure what you're testing by lumping the grounds together and checking against a chassis ground. In theory, on the other side of the L-Jet each of the ground wires connects to a power source, not a common ground. In that case, I'm not terribly surprised you're getting a high resistance.
Tom been following along with my fingers crossed for you. Wanted to let you know, there's an '84 parts car on Craigslist, guy is in Fallbrook. Ive been in touch with him about other parts, but I asked and he does have the ECU and is willing to let it go for $100. I know you wanted to borrow a known working one, but if you can't find one to borrow, this might be a cheaper option/gamble. He has a 909 area code. Good luck, keep at it and be patient. You'll get her goin soon enough.
Looks like you have definite ground problems but have you checked the connector at the TSZ 'spark box'? If the L-jet does not get a spark signal it will not pulse the injectors and shut off the fuel pump. It is located near the 14 pin connector in the engine bay.
I have not checked that yet, "just" looking for power in & signal out? Are there any multimeter tests I should do?
Thank you!
Edit - I had to go back and look at my notes to realize that I did actually pull this connector and it looked clean. I also confirmed that I have power there via this test;
I assume you have performed all of the tests in that part of the manual, book 1A section 28?
This is all I can find for testing the TSZ:
Readings should measure between 485 - 700 ohms.
How are you testing the grounds? Test from the connector at the computer to the wires at the cam tower for continuity. Your meter should be able to reach. I am skeptical that all four of the ground wires are broken but the others are intact. I saw that you cut out the ring terminal and installed spades, did you ground those to the cam tower somehow?
You cut the ground wires back at the computer, can you splice in new wires and ground those at the cam tower with ring terminals? You can run them outside the car temporarily just to see the readings you get.
I would recommend getting the 5 disc set from 928sRUS. There are manuals included on the all of the Bosch fuel and ignition systems and how to troubleshoot.
We will see, I'm not really expecting a whole lot. If it doesn't fire after swapping in this L-jet it doesn't necessarily mean a lot until I can check the one that came with the car and this one with a known to be healthy 928S.
That does raise the question-where do you go to get an L-Jet rebuilt if it needs it?
Quick update-it did not fire with the new box either, but I have no way to tell whether or not the new boxes any good.
I put a multimeter on one of the injectors and I have 12.53 V with the ignition on, but that only drops to 11.24 V when she's being cranked. How far should and ejector drop if the system is healthy?
No pulse after cleaning that all up on either L-Jet.
Happily my oil pressure gauge is very snappy now so I suppose it was worth it (needed to be done obviously).
I think it is time to write the current injection harness off and replace it. Oh well.
Going to move ok to the fuel system now - pretty nasty in there. Look at what spilled out when I loosened the end cap at the end of the rail to it he pressure gauge. Nasty!
06-23-2017, 11:44 PM
