I've developed a misfire, and I could use a hand....

[Derick]

So it's not big enough where it's thrown an engine light yet, but I can definitely feel it.

The plugs are about 3 years old, and the wires are just over 2 years old. With those having been replaced, I figured for certain it was the coil. That was the only part in the per cylinder system that hadn't been replaced. Well I replaced the coil...and....same thing. I'm getting between 2-22 misfires in the misfire current PID. I swapped wires the other night.....same thing, cylinder 2, spark plug wire didnt affect anything. So, today I replaced the plug. Seemed to be great for the short term, but misfires came back. I would have preferred to have inspected the plug....but it fell out of the puller, and got lost into the abyss. It was just under the exhaust manifold. I tried to remove it with some forceps but pushed it somewhere I couldnt find again.

It's at about 42% throttle as reported by torque, just giving it enough gas to maintain a speed. Short jolt or studder. Under WOT, she purrs along just fine. It's very weird, but I'm not sure what to check out next.

 

[Geotrash]

So it's not big enough where it's thrown an engine light yet, but I can definitely feel it.

The plugs are about 3 years old, and the wires are just over 2 years old. With those having been replaced, I figured for certain it was the coil. That was the only part in the per cylinder system that hadn't been replaced. Well I replaced the coil...and....same thing. I'm getting between 2-22 misfires in the misfire current PID. I swapped wires the other night.....same thing, cylinder 2, spark plug wire didnt affect anything. So, today I replaced the plug. Seemed to be great for the short term, but misfires came back. I would have preferred to have inspected the plug....but it fell out of the puller, and got lost into the abyss. It was just under the exhaust manifold. I tried to remove it with some forceps but pushed it somewhere I couldnt find again.

It's at about 42% throttle as reported by torque, just giving it enough gas to maintain a speed. Short jolt or studder. Under WOT, she purrs along just fine. It's very weird, but I'm not sure what to check out next.

Any change in the engine noise from outside? Knocks, etc? Injector connector tight?

 

[tungsten]

Lol,plug fell into the abyss.Hate it when that happens.

 

[Fless]

Lol,plug fell into the abyss.Hate it when that happens.

It wanted fellowship with the 10mm socket....

 

[OR VietVet]

Use a magnet to retrieve the plug and do a comparative compression test with next cylinder over, #4.

 

[Derick]

Use a magnet to retrieve the plug and do a comparative compression test with next cylinder over, #4.

I tried, I have no idea where it is. Cant feel it by touch, cant see it by eye. Fished around for quite awhile trying to find it with a magnet.

 

[Derick]

Any change in the engine noise from outside? Knocks, etc? Injector connector tight?

Everything sounds normal.

 

[Foggy]

Well , you said "COIL" .. you have 8 of them and they fail very rarely...
But with the stuff you've done, I'd suspect maybe some torque converter shudder maybe,
although less common on the 4L80E...
or Even Spark Plugs Still... Use AC Delcos from a reputable source... Lots of
fake parts out there these days

 

[Derick]

Not TC shudder, I can see the misfires happening in torque. I replaced the plug with an AC Delco 6. Seemed ok for the short term, but it came back. I can also see specifically its cylinder 2, so I replaced the cyl 2 coil and no change.

 

[OR VietVet]

What does the newly replaced plug look like now that it was good with new and then not good? I know I suggested to run a compression test on that cylinder and the next one to it. They are easy enough to remove the plugs. C'mon man. May have great compression but eliminate the basics one step at a time plus now you can see the new plug. Post pics and compression test results.