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Discussion Starter #1
These grounding wires go from the bolt in the valve cover just above the #3 plug, meet up with some other wires in a snake, wrap around the hood release, meet up with yet more wires, then sort of disappear. I need to check the actual grounding ends as I'm having intermittent power loss with sudden kick back in. It's either the ignition coil/module or a ground issue. I've checked, repaired and cleaned every other ground in the engine bay, as well as general wiring, but this has eluded me. The wiring diagram isn't much help to me.
Any ideas?
 

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Trained (ex)Professional, , 1953-2018 RIP,
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The injectors are powered by the combi relay when ever the key is turned on. The injectors 'fire' when the ECU pulses the ground circuit. So in other words, the injectors are not hard grounded to the chassis. They are grounded through the ECU.
 

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The injectors are powered by the combi relay when ever the key is turned on. The injectors 'fire' when the ECU pulses the ground circuit. So in other words, the injectors are not hard grounded to the chassis. They are grounded through the ECU.
Yes, what he said.


Also, if your power loss is intermittent and sudden - it is almost certainly not fuel related UNLESS you have a shorting injector harness. Even then, it wouldn't be like an on/off switch because each bank of injectors has its own driver (from memory).
 

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Discussion Starter #4
FYI, for anyone with similar issues, it was an overheating ignition coil ballast resistor. I installed a brand new MSD Blaster II coil, bypassed the resistor, problem solved.
 

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The injectors are powered by the combi relay when ever the key is turned on. The injectors 'fire' when the ECU pulses the ground circuit. So in other words, the injectors are not hard grounded to the chassis. They are grounded through the ECU.
This is technically correct as the wiring diagram will show - but, there are two harness grounds that appear to come-off the injector harnesses, one for each bank. Those are usually bolted to the left side (North America) valve cover or at one of the Aux Air mounting bolts. Item's #5.

FuelSYS4.jpg
 

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Discussion Starter #6
As shown the the first image, correct? The ground strap from the plenum to the other head cover is for the TPS and CSI... I think.
 

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Yes to the image, but NO to question Chairman, those are grounded through the harness as well. The flat braided plenum strap is to ground the plenum itself as the phenolic spacers under the intake tubes are not metallic. This could result in static charge build-up due to the friction of the air flowing through the plenum. This could be very bad if it built-up and then jumped somewhere that goes back to the ECU!

I always thought that the two eyelets were Injector grounds because they were on the injector part of the harness, but according to the full FI wiring diagram, they each have their own ground PIN at the ECU connector. So these are "common" harness grounds.
 
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