o2 Sensor Data

[tatasta]

Originally Posted by xc_SS/RS

Did he or you try moving the #3 coil pack to a different cylinder to see if the problem stayed, or followed the #3 coil pack?

Thanks for the reply. Yes. Coil packs, injectors, plugs and wires have all been moved around throughout trying to track this down. The tech at the dealership tried it again with no change.

Thanks again

[tatasta]

bump up.

Are there many reasons that would cause low voltage to a coil other than a bad ECM?

If so, what are the fixes?

Thank you

[PepeLePew]

I don't think it is an ECM, otherwise you would have low voltage to all the coil packs most likely. You said you moved the coil packs, plug wires, and spark plugs to other cylinders and the problem stays with number 3, correct? If so, my guess is that you have an issue with your coil pack harness.

I'd start by checking the resistance on the wires in your harness. To do this, you can back probe the connector at both the coil pack and the connector where it connects into the main harness. The black wire is the negative on all connectors and the pink is ignition voltage. Then set your multimeter to read ohms and probe both ends of the harness. If the resistance of any wire is more than 2ohms, you probably have a wire that is going bad most likely due to heat or from being tugged on too hard when removing connectors. If that is the case, the you can try to find the spot that is bad (either coming loose from a connector or insulation on a wire being torn somewhere) and repair it. Or you can buy a new harness for about $75.

[PepeLePew]

One more thing... I know you said the service tech ohm and load testing the wiring already. Depending on how he did that and where a faulty wire may be, it might not have shown up in his testing. For example, if a connector went bad during the tear down process when you put the SC on, it could be a loose wire at the connector. If the tech probed the wires by sticking them through the insulation, the short would not be apparent.

Also, the way I understand it, the ECM sends the same signal to 2 cylinders at a time on the firing stroke. That tells me that if it was an ECM issue, you would have the identical issue with cylinder 2 since it fires at the same time. So if everything else has really been checked by the service technician (plugs, coil packs, wires) and the problem is identified as voltage related (not fuel), then it has to be the harness.

The only other thing I can suggest, is to double check yourself that it isnt a plug wire, spark plug or a coil pack by moving them yourself to see if the problem moves with it. I know you said you trust the tech and he was a good guy... that very well may be the case and he could have done everything he said, but I've had too many past experiences with others working on my cars and messing stuff up or not doing what they said... so I am skeptical.

Best of luck to you. Hang in there and you'll figure it out soon.

[tatasta]

Originally Posted by PepeLePew

One more thing... I know you said the service tech ohm and load testing the wiring already. Depending on how he did that and where a faulty wire may be, it might not have shown up in his testing. For example, if a connector went bad during the tear down process when you put the SC on, it could be a loose wire at the connector. If the tech probed the wires by sticking them through the insulation, the short would not be apparent.

Also, the way I understand it, the ECM sends the same signal to 2 cylinders at a time on the firing stroke. That tells me that if it was an ECM issue, you would have the identical issue with cylinder 2 since it fires at the same time. So if everything else has really been checked by the service technician (plugs, coil packs, wires) and the problem is identified as voltage related (not fuel), then it has to be the harness.

The only other thing I can suggest, is to double check yourself that it isnt a plug wire, spark plug or a coil pack by moving them yourself to see if the problem moves with it. I know you said you trust the tech and he was a good guy... that very well may be the case and he could have done everything he said, but I've had too many past experiences with others working on my cars and messing stuff up or not doing what they said... so I am skeptical.

Best of luck to you. Hang in there and you'll figure it out soon.

Thank you for all the info. I really appreciate it. I will do a bit more investigating on my own.

Would I need to replace the entire engine harness or, is there a harness just for the coils that attaches to the engine harness?

Thanks again

[tatasta]

Nevermind... I see the harness you are referring to.

Thanks