Out of the blue, I leave my car alone for a week and the next time I drive it, it's got a bad misfire. My scan gauge says it has these two DTC's. I looked them up and it says I have a misfire on cylinder 2.

I googled it and it looks like it's typically an intermittant issue. I'm experiencing it in and out also. I checked spark on #2 three times, last time it wasn't showing any spark so I decided to try and switch out the coil pack and plug wire from another cylinder to see if the problem would migrate to another cylinder...it stayed on #2.

So this leads to the wiring. Now my question is, what would be the easiest way to track this down? All four coil packs consolidate into one weather pack on the passenger side. Which pin on that weather pack can I check for voltage while cranking to see if cylinder #2 is firing? I am really hoping it's just the coil bracket mini-harness and not something in the actual engine harness. I suppose an easy way to check would be switching out the passenger side weather pack for the driver side and seeing if the DTC migrates to the driver side of the block. But I'd really like some input.

Thanks!

 

I would use a lab scope with long test leads to monitor the signal while I drive the car. I know not everyone has this capability. You need good wiring diagrams or use a ohmmeter to find which terminal in the connector goes to coil #2. Misfire codes are 300s, as in P0301-P0308. P0300 is random, or multiple cyl misfire. You say you have a code P0352? I'm not where I can access All Data right now, but be sure of the code number before you get too deep into searching. The three hundreds are ignition codes(P0300-P0399). They deal with all ignition related circuits and components.

Swapping coils in an old school method of isolating the trouble to the coil itself. Swapping the coil harnesses will do the same for the harnesses. Be sure to check all connections in the circuit from the PCM to the coil. Take care of course with the harnesses and wiring in general. GM got very thrifty with copper on the later harnesses and the thin wiring breaks way too easy. They commonly break close to a connector.

 

From what I found on a google search, the P035x is misfire on x cylinder. So P0351 would be cylinder #1, my code is #2, and so on...


I'll switch over the coil harness tomorrow and see if the issue migrades to the driver side bank. I'm hoping that it does, because finding a new coil harness would be easy.

 

Could also be a misfire from a defective fuel injector, a fuel pressure balance test would confirm this, pulse each injector for a timed amount and the pressure should all drop roughly the same. The bad injector will not drop the fuel pressure much if at all.

 

Or you could just move the injector

Various diagrams in here
http://www.lt1swap.com/2001_ls1_schematic.htm

 

Misfires are P0300-P0308 always have been always will be. Its OBDII standard. If you have code P0352 it's a variant and you need to carefully read the description because it is a more specific failure than a simple misfire.

On checking All Data, I find that DTC P0352 is specific to the coil circuit. It is not an injector or any other type of misfire. Try swapping coils with another cylinder and see if the misfire, and DTC follow the coil. For instance, if you swap coils with cyl 4, you should expect to see a DTC P0354. If the misfire and DTC stay as they are, you need to find the issue in the harness, or PCM.

 

I did swap coils with the number 1 cylinder, and the issue didn't migrate with the coil. I'm going to swap coil mini harnesses tonight and see if it migrates then, if not then I'd assume it's a broken wire, hopefully not a bad computer though??

 

PCMs rarely go bad short of user error

 

I have replaced PCMs for bad quad drivers. The coil on plug PCM has a quad driver for each coil. You can try using a DVOM with a Hz scale to read the primary ignition pulse to coil #2. The DVOM won't show you waveform but you can compare the pulse with that of a good cylinder to look for any difference. Before you replace a PCM, you need to have someone use a lab scope to verify that the waveform of the primary pulse to #2 is defective at the PCM.

Also, if the PCM has had a quad driver fail, it is wise to determine if the failure was caused by a shorted coil or circuit. Use your DVOM on the ohms scale to measure resistance of the coil and the circuit between the PCM and coil. Check too for any short to ground or power.