- Thread starter
- #26
Busdownthotiana
Proven Member
- 76
- 29
- Jul 24, 2023
-
Florida
I agree with the ecu bit, but I just got my ecu back from ecmtuning. I spoke with Dave Mertz who I told also about the injector plugs reading 12v unplugged and he replied withKey on - ECU Unplugged
The only way you can measure 12v at injector pins 1, 2, 14, and 15 in the ECU harness is if you have a complete circuit from the battery - through the MPI relay, through the resistor pack, through the injector coil and all the connected wiring harnesses up to the ECU. If you ground each pin (1,2,14,15) one at a time, you should hear the injector open and close. If you don't - then the issue is upstream from the ECU.
Since you are getting 12v at the ECU - and the ECU detection logic is failing, this tends to point to the ECU as the problem.
Did you have the ECU inspected and fixed by ECM Tuning? The capacitors on the boards leak and mess up traces on the board.
“The best way to test for pulses would be to use an oscilloscope with the injectors connected normally.
With the injectors unplugged, you'll still see 12v on ECU pins 1, 2, 14 and 15 when using a high-impedance meter because the ECU has an internal resistor of somewhat high value pulling up to 12v as part of the injector-circuit malfunction detection circuit.
Dave Mertz
ECMTuning, Inc..”
Right now I’ve tracked down that I am indeed receiving injector pulse at all 4 pins of the ecu. I’m not exactly sure why the ground signal is not traveling upstream as you said.. I’ll try back probing with the injector plugged in to see if I still get a reading which I don’t see why I wouldn’t. 4-5” away from the ecu im still receiving pulse too. It’s a strange situation for sure.
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