I don't know if the arcing compromises the wire insulation or not but I would think that it would be obvious visually. On your question of crank relearn and misfires, I checked with Les and he confirmed that this should not cause a felt misfire. He also reminded me that you should minimize live data parameters on any given capture and minimize gauges because of the limited band width of those BT scanners. This may prevent things like O2 sensor graphing from providing useful data.


George

 

Ya that was an old screen shot and I just picked the first one I found to show that the cmp was near -/+2. I know there's too many things running.

 

no problem. Knowledge is power. George.

 

So I had severe acring going on due to leaking wires from all the misfiring. I swapped out the leaking wires with ones I had previously replace. So I have half of my wires ngk and half ac Delco temporarily until my new wires come. I don't see any leaks anymore and it runs way better. Now for some reason I get the cel light immediately after I start it but not all the time p0351. I'm monitoring the misfire with the scantool and most of the time it's zero's but sometimes I'll see few misfires on 2 or 3 cylinders. I've misted and don't see any leaking wires. I'm thinking that the cap has lost integrity and the spark is going though the weaken traces of the top of the cap on the inside. I bought a cheap cap to swap out and see if it corrects the problem. Sparks have been jumping around for 2 years I'm sure it's broken down the insulation on the terminals inside the cap or at least I'm hoping that's the case because I know I'm very close to correcting my misfire problem. I'm sure if the arcing has damaged the insulation on the wires that it's also done damage to the insulation on the cap traces as well. What's you thoughts ? Thanks again

 

I did not see any carbon traces inside that distr cap.

Its very unusual to have so many arcing ignition wires, especially from two top brand names. That P0351 code says that the engine computer is seeing unusual voltage levels on the white ICM control wire from the computer to the ICM. Does that ICM connector look OK? You should inspect that harness and test that white wire for excessive resistance. I can help with that.

George

 

Ya the connector looks fine. So what's the procedure for testing the resistance on the white wire ? Is it just disconnecting the harness from pcm and placing one probe on the white wire in the harness and the other on the white on the icm and looking for something close to 0 ohms ?

 

Yes, but I would go the other way around. Disconnect the harness at the ICM and make one connection at the open white wire there and then either probe the other end of the white wire near the PCM connector or back pro.be the connector. Once you’re set up and measuring move the harness around and watch the reading.

George

 

So the connector at the pcm doesn't need to disconnected ? Would you by Chance have a diagram of the connector at the pcm or know which connector and pin number would be the white wire ?Does the battery need to be disconnected ? Also what the best way to back probe with a paper clip at the pcm ? Or is it easier to take off the connector and do it that way ? I'm also wondering about the cam sensor. I'd like to see if that's putting out a reading. I guess it can be checked using the scan tool and the cpk pid ? The reason I'm concerned about the cam sensor is because I've had one go bad on me once already. It looked like it over heated and cracked. That sensor sends a signal to the white wire as well right ?

 

For resistance testing you do not need to disconnect at the PCM. I am trying to minimize jacking with the large PCM connectors because if there is an accident and you bend or break something its bad news. You can back probe into the back of the connector with a T pin or paper clip or pierce the wire with a straight piercing probe or a clamp down piercing probe. You can take the pcm connector off if you like but be careful.

There is a crank sensor at the front engine housing and a cam sensor at the distr. neither sensor is directly connected to the white wire from the PCM to the ICM. They both have reference voltages and signal output which both go to the PCM. The PCM and the ICM are the only two things on the 'ignition timing signal" white wire.

The crank sensor initiates the spark pulses by way of the CPK>PCM>ICM>Coil>Distr>wires>plugs. The engine timing is controlled by the PCM on the white wire. The cam sensor is a monitoring device to help the PCM determine the distr/valve position compared to the crank sensor timing. Cam retard goes out of spec due to timing chain and cam/distr gear wear. I don't know if a failing cam sensor can give a logical but out of spec reading. The engine will not run without a crank position signal but will run without the cam sensor. If CMP retard is within spec the cam sensor is connected and functioning. Can it be intermittent, sure.

The only way to completely test the output of these two hall effect sensors is with an oscilloscope. This is also the best tool for fuel injector, primary/secondary ignition and class 2 data line testing but that a subject for another day. Most people here do not have one of these tools so we have to make due with more basic first order testing with hand cranking and dc voltage monitoring or AC voltage readings which tells us if the sensor is producing an output but not how well it functions at operating speed on a warm engine.

George

 

Ok tested the white wire and eveything looks good 👍. When I used the scantool setup cpm pid there's zero reading.

The crazy thing is I can clear the codes and the light will stay off but as soon as i start the truck.... not all the time but most of the time..... it will instantly trigger the cel light again.