88 Corvette injectors fire when key on ....
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Cruising
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Le Mans Master
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From: near the thumb in the mitten
With injectors unplugged, install a noid light.. Disconnect ECM. Does noid light blink when key is turned to run. The injectors are powered by a key on fuse. The ecm grounds them. I have experienced failures like this with non gm reman ecms.
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Cruising
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With ecm disconnected one wire has constant 12 volts positive..no ground
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Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
If the injectors don't come on when key is turned to run with ecm disconnected, but will if ecm is connected. I would replace the ecm. There is a slight chance if the distributor was worn distributor could cause it intermittently, so you could see if there is play or wobble in shaft. You just need to try to shake rotor and see if it moves or wobbles side to side.
Thread Starter
Cruising
Joined: Dec 2017
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If the injectors don't come on when key is turned to run with ecm disconnected, but will if ecm is connected. I would replace the ecm. There is a slight chance if the distributor was worn distributor could cause it intermittently, so you could see if there is play or wobble in shaft. You just need to try to shake rotor and see if it moves or wobbles side to side.
Team Owner
Joined: Jul 2004
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From: Hartford WI
If the injectors don't come on when key is turned to run with ecm disconnected, but will if ecm is connected. I would replace the ecm. There is a slight chance if the distributor was worn distributor could cause it intermittently, so you could see if there is play or wobble in shaft. You just need to try to shake rotor and see if it moves or wobbles side to side.
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Cruising
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Race Director
Joined: Apr 2002
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From: Anaheim CA
Sounds like a short in the injector wiring. Unplug ALL the injectors (all 8 are in parallel, so if one is plugged in it will look like a very low resistance). Measure from the light green wires to ground. Measure from the light blue wires to ground. Unplug the connectors from the ECM when you do this because the light green and light blue wires are connected together inside the ECM.
Thread Starter
Cruising
Joined: Dec 2017
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Sounds like a short in the injector wiring. Unplug ALL the injectors (all 8 are in parallel, so if one is plugged in it will look like a very low resistance). Measure from the light green wires to ground. Measure from the light blue wires to ground. Unplug the connectors from the ECM when you do this because the light green and light blue wires are connected together inside the ECM.
Le Mans Master
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From: near the thumb in the mitten
The injectors are fused 12v (2 fuses right and left) when key is turned to run or start. With the injectors unplugged only one side of connector should have 12v. Since you have the injectors unplugged you could ohm them to make sure they are within spec.s. With the injectors plugged in their will be voltage on both sides, the circuit is looking for ground from ecm. If harness is shorted the injectors should have cycled when key was tuned to run with the ecm unplugged. An injector with low resistance will cause a miss in 3-4 cylinders on that branch. Current follows the path to least resistance, the lower ohm injector would be the least resistance. Open injector causes miss on that cylinder only. Do all injectors still cycle with key turned to run?