[V8] ECU grounding, etc.

[Coleman, David]

So yesterday I finally got a chance to spend a few hours w/ my
poorly-running V8.  Here's a quick recap:

+ Car starts only after a few 1-second cranking sessions.  Won't start
w/ extended cranking.
+ Once warm, idle begins to fluctuate wildly (0-1500 rpm) until engine
dies
+ Engine suddenly bogs down to the point of killing the motor if
anything close to WOT, either revving or driving.  Sort of like I'm
mashing the brake pedal while keeping the throttle open
+ Car runs WAY too rich, in all running/driving circumstances

I've replaced the FPR and spark plugs.  From there:
+ Code consistently shows 2324 (bad ECU ground, MAF wiring)
+ Running diagostic output tests indicate all injectors click, ISV
actuates, but carbon canister solenoid no good
+ Replaced canister solenoid and associated vac hose clamps, now clicks
away during output tests.
+ About this time chunks of ceramic began appearing on the ground behind
tailpipe
+ Cats wasted.  Gutted what was left, replaced center muffler, left rear
section alone (verified no cat innards got caught in there).

No change... this brings us to yesterday.  Test light and multimeter in
hand, I went through the manual's check process for ECT sensor (G62), O2
sensor, and MAF sensor -- all failed the checkout, with all blaming the
ECU or its wiring.

So I pulled the ECU harness connector away and did two checks before it
was time to call it quits:
+ ECU voltage supply check asks to confirm ground at terminals 10, 14,
19, 24, and 54 of the harness connector ---  All were good except at 54.
+ I also picked back up on the MAF sensor check procedure, which was
asking to verify continuity between ECU harness connector pins 19 & 37.
No good.  Blames an apparent short between ecu pin 37 and terminal #5 of
the MAF sensor connector.  So far no luck finding a short...

So the upshot is: how does terminal #54 of the ecu harness connector get
its ground?  Any other thoughts?

Delirious in Delaware,

DaveC.
'91 V8 5-speed






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