Chasing Misfire

[iamdub]

IIRC, a crank-to-cam mis-sync commonly causes an intermittent misfire on #7 and/or #3 on the Gen3 engines. It may do similar on the Gen4 but maybe another cylinder/cylinders. Something is different on them because the crank sprocket for the timing set is clocked half a tooth differently between the generations.

I'd definitely try that even if it's not THE problem since it could be a minor, unseen problem. At least it could be ruled out for this and future issues.

You swapped packs, but did you test the signal going to the #2 coil to ensure that the PCM is firing it?

 

[badandyturbo]

IIRC, a crank-to-cam mis-sync commonly causes an intermittent misfire on #7 and/or #3 on the Gen3 engines. It may do similar on the Gen4 but maybe another cylinder/cylinders. Something is different on them because the crank sprocket for the timing set is clocked half a tooth differently between the generations.

I'd definitely try that even if it's not THE problem since it could be a minor, unseen problem. At least it could be ruled out for this and future issues.

You swapped packs, but did you test the signal going to the #2 coil to ensure that the PCM is firing it?

No not yet. I am having difficulty verifying which wire to test. The harness has 4. Pink, purple and 2 blacks.

 

[swathdiver]

No not yet. I am having difficulty verifying which wire to test. The harness has 4. Pink, purple and 2 blacks.

My manual shows wire PK (Pink) as Ignition 1 Relay, BN (Brown) as Low Reference, and OG (Orange) as ECM Ignition Control and BK (Black) as Ground.

Coil 2 has Pink, Black, Brown and Orange (OG)
Coil 4 has Pink, Black, Brown and Dark Green (D-GN)
Coil 6 has Pink, Black, Brown and Light Blue (L-BU)
Coil 8 has Pink, Black, Brown and Purple (PU)

Coil 1 has Pink, Black, Brown and Purple
Coil 3 has Pink, Black, Brown and Light Blue
Coil 5 has Pink, Black, Brown and Dark Green
Coil 7 has Pink, Black, Brown and Orange

 

[iamdub]

My manual shows wire PK (Pink) as Ignition 1 Relay, BN (Brown) as Low Reference, and OG (Orange) as ECM Ignition Control and BK (Black) as Ground.

Coil 2 has Pink, Black, Brown and Orange (OG)
Coil 4 has Pink, Black, Brown and Dark Green (D-GN)
Coil 6 has Pink, Black, Brown and Light Blue (L-BU)
Coil 8 has Pink, Black, Brown and Purple (PU)

Coil 1 has Pink, Black, Brown and Purple
Coil 3 has Pink, Black, Brown and Light Blue
Coil 5 has Pink, Black, Brown and Dark Green
Coil 7 has Pink, Black, Brown and Orange

So, would he put a DVOM on black and orange and test for a pulsing 12V?

 

[swathdiver]

So, would he put a DVOM on black and orange and test for a pulsing 12V?

Sounds right. When we looked at it the other day, I could not find the menu to test the injectors but did find it on mine a few days later. So when we meet up again we can run a test via the Tech-2, as long as his computer programming supports it.

 

[91RS]

We've seen some chewed up cam and lifters causing misfires at idle ONLY with no noise. Once you've verified you have spark and fuel, mechanical is all that's left.