no chance he put a new computer in the car then jump started it?
This could be killing a computer..

SO have him charge the battery with a 6 amp charger for 4 hours with the battery disconnected
Dont mess with the aftermarket chips .
for the amount the car gets driven, keep things stock

 

QUOTE
- New rebuilt computer installed from Roger, car won't start (testing showed no spark and no signal to the noid lights)
END QUOTE

This suggests that the two leads on the positive post of the battery are loose.... and/or relay problems.

Obviously no spark is nothing to do with the LH. If the LH rebuild is one of mine, the new tile is much more resiliant to volts spikes than the original design. The only time one has failed was when a roadside recovery man connected a 30v "boost start" device. Then there was a very obvious burnt smell from the LH ECU :-)

 

John,

Both the loaner LH and the one from Roger won't start his other 928 (SC'ed 88), if it were just lose wires, you would think the computers would be fine. I'll ask him to check those wires just in case. We did swap out relays quite a bit when I was at his place a month or so ago.

 

Hi Don
OK, understood. But does the s/c car have special software in the LH ?

 

Yes, the SC car does have special chips, but I figured it would at least start on a standard LH. Also I tested the first failed LH, and the loaner LH in my 89 when I was out there and it wouldn't start either.

 

Well, it's certainly a puzzle..... do both EZK and LH ECUs that have been tried in the first car seem to have failed ? Or mainly LH ?

 

Only the LH has been swapped out/tested.

 

I can't fault your logical approach... but an "ECU killer" suggests something very seriously worng with the car in question.

 

Agreed, and that doesn't really fit this very unmolested car, one of the nicest I have ever seen. It's officially Bud's wife's car. Back 7 or 8 years ago they were active in the PCA and she had to quit entering the car in the concurs because she felt bad about winning every time.

Maybe I'll try to get back out there next weekend and recheck a few things.

 

Just to close out this thread, Rich was kind enough to check out both computers and found that the eprom chips were installed backwards. So was not a case of a car damaging a computer.

 

Don,
Interesting!
Fault finding logic and failure mode analysis dictates to go back to "what was last done" and check first.
Good to see the fault was rectified.
Tails 1990 928S4 Auto