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Hello I have a 1997 Chevy lumina, 3100 engine, crank no start, I have checked for spark and have good spark, it will run off of spraying a fuel source in the intake, fuel pressure is good but I have no injection pulse, power to injector but no ground side pulse from computer, I have checked cam and crank sensors, both are Hall effect and I believe both are good, the crank sensor signal wire pulses around 24-30 times per revolution, I don’t have a scope so I’m watching a multimeter as I turn the engine by hand, I also checked the cam signal the same way and it pulses once every 2 revolutions of the crank pulley, I’m about to
call a bad driver on the computer but I wanted to see if anyone had any other ideas before I called it.
In this case, you Need a Wiring-Diagram to eliminate all possibilities. You should check all input-signals direct at the ECU, the Outputs too. Maybe you have only a broken wire and the ECU doesn't see the cam or crank-signal but you can see it at the sensor directly.
Yes I checked the cam and crank signals at the ecu, I also checked for the injection pulse at the computer and I don’t have any, I rang out all the wires from the computer to each connector with an ohm meter and they all tested good
So, you have cam/crank signals direct at the Computer and no injection pulse Output, correct?
If all Power/GND Connections at the Computer are fine and no anti-theft System is active, i whould also say the Computer is bad.
But i really hate this to say, my expierience is, that mostly something else is wrong, not the Computer!
Yes, I will double and triple check everything again tomorrow but that’s what I came up with today, do you know if the computers on these need to be flashed or anything or if I can just pull one from a junkyard and throw in to try?
I can't say 100% but i guess it's not probrammed, because it's an old style System. Let this question answer somebody else
But if your Computer is really cooked, you have to find out why. Maybe a coil is bad and fired trough the control-wire back into the Computer and killed it.
If you find the computer is bad there are some services on eBay where you provide Vin and they give you another computer. I didn't need to send a core when I did it on a GM on the past. About a week turnaround. Just have to do key and crank relearn. Takes about 30 min.
ok Guys just wanted to give you an update to what happened with this and how it got resolved, I did not replace the computer, it ended up being 2 different problems, first problem and original problem was the security system, which I bought a gm vats bypass module from eBay and installed, once installed, and this is where it got screwy, rather than once again testing the computer output for a injector ground pulse I just tried to start the car, it didn’t start so I assumed that it was the same problem, NEVER ASSUME! so after a couple days of beating my head off the wall I re checked for injector pulse and realized I actually had it and I was looking at another problem, that problem ended up being a weak fuel pump, it was running and actually pumping fuel but it wasn’t building enough pressure, so overall I had a security issue and a bad fuel pump threw in the mix which really had me confused for a little bit. Thanks again for all the feedback!!
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