2012 Suburban Misfire #5 drama

[Doubeleive]

Yes, can you still rent those at auto parts stores?

Maybe the kit is only $25-30 probably can get one at harbor freight

 

[Fless]

I agree that more tests are needed before tearing down. In addition to the noid light test, I'd probably borescope that hole and turn the engine over by hand to verify that both valves are opening and closing fully, and nothing looks off (like very clean head and valves combustion side surfaces).

Also, an injector balance test might be worthwhile.

 

[Keiterburb]

for me pulling it apart and not finding anything mechanical wrong would be a last resort. but yeah, a afm delete would at least make it worth while.

when I said check for power, I'd use back probe pins, at the individual connectors on the coils. these are lole 5$ on Amazon and hope there's a lower voltage on #5. you can follow the wires thru the seal and to the pin inside without damaging anything.

you probably don't have it handy, but I'd pull out my pocket scope next and check the trigger wire at the coil from the ecm. but these days mechanical work is the last thing I like to do. if your multi meter does hz. it might tell you something, but not sure.


byond that I'm out of ideas.. back to basics. have you looked at the fuel trims and miss fire counts? when it's missing on a gm the miss fire number will constantly count up while it's missing. that and something as simple as a loose spark plug will miss.

Thanks for the suggestions; I have been shooting power with disconnected connectors but will check for needle probes around my garage or order a set to test while running. Also, ordered noid light test kit as I am was out in Wyoming and part stores have no loaner tools.

I have an Innova 5610 and have watched the live data but unfortunately no live misfire counter. It was pulling fuel from bank 1 while running. Would love to get a great scan tool one day but can never decide on one.

 

[Keiterburb]

Maybe the kit is only $25-30 probably can get one at harbor freight

Placed on order, will take a few days to arrive

 

[Keiterburb]

I agree that more tests are needed before tearing down. In addition to the noid light test, I'd probably borescope that hole and turn the engine over by hand to verify that both valves are opening and closing fully, and nothing looks off (like very clean head and valves combustion side surfaces).

Also, an injector balance test might be worthwhile.

I have a borescope on my desk at work, I'll bring it home tomorrow while the plug is still out from leak down check today.

 

[j91z28d1]

huh so it has a miss fire fault code and feels like it's missing at idle but you're not seeing the miss fire numbers climb.

I'm not sure what that means, but it's not what I've seen happening on my stuff.

you have a very interesting one.

 

[Keiterburb]

huh so it has a miss fire fault code and feels like it's missing at idle but you're not seeing the miss fire numbers climb.

I'm not sure what that means, but it's not what I've seen happening on my stuff.

you have a very interesting one.

Not exactly, I have no misfire counters on my ******** live data so I don’t know. Just know it has a miss and code returns

 

[rdezs]

I'm thinking you're not getting a code for misfire because it might not be misfiring..... As far as the coil and spark plug go. But I would definitely want to confirm that with live data while it's running at different RPM, and completely rule out the electronics including the ECM.

Having passed a leak down and compression test, and only happening on one cylinder..... I'm leaning toward it's one of the lifters acting up. I'm wondering if the fouling of the spark plug is due to either the exhaust valve not opening all the way and that cylinder can't push all the exhaust out, or the intake valve not opening all the way, not allowing enough air, which also would foul the spark plug. Above vital with more oil pressure, I can see the lifter functioning properly.

How is your oil pressure by the way?