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Questions are great I just didn't want to overload my post with a ton of information . This is a fresh engine rebuild with a larger cam then Factory. After the rebuild it ran rough and found 4 injectors were bad replace the four injectors started the motor ran great and idled great. Got up to Temp with no problems and issues. Then went to take it for a safety inspection check engine light came on and started to throw the p0336 code. Erased the code the motor ran fine. When I picked it back up from the safety inspection it was running like it was hitting on only four cylinders again. Bought a new installed it cleared code this time it came back immediately after startup. Thought maybe I got a bad new sensor so pulled a sensor out of my Yukon that I knew was good, installed it and it would immediately throw the code after startup. Began to chase down the wires could not find where anything was broken or chewed on and all grounds were solid as I cleaned up all the frame connections with a sander prior to installing them all. That is when I measured the voltage at the sensor was getting 11.6 volts across the power wire and the ground at the plug. Then I tried the power wire straight to frame ground and still got 11 .6 volts.
That voltage seems low, what is your battery voltage?
Also you really need to do a voltage drop test with it running, and by voltage drop test I mean from the positive battery terminal to the 12v terminal at the connector.
Do the same with the ground. A voltage drop test checks the circuit when it's loaded. A weak circuit will act completely different loaded compared to KOEO.
Is there any tricks to getting to the sensor while it is running since it is behind the starter? I was thinking of using an old sensor end and another connector plug to make an inline pigtail i could splice into so i can test. Is that my best option?
Here is the results of my voltage drop test. The black wires means that one black wire was connected directly to the negative post of the battery. The Red wires mean one red wire was connected directly to the positive post of the battery. In the picture of the plug below the middle purple wire was connected to the blue back pin wire, yellow to yellow and green to green.
Is it possible to do a relearn with P0336 error code? I don't have a scanner to do the relearn. Would be willing to get the necessary software. Is HP tuners are recommended software I should get? Thanks for helping me out.
07-30-2019, 03:45 PM
