Misfire - Wet Spark Plug on Cylinder 3, But Cylinder 4 Low Compression...

[y2k_o__o]

Yea. Who knows really what happened. About 30 miles driven on the car so far, everything seems fine.

To OP, any update 4 months after the injector cleaning?

[BMWahba]

Drive it hard, avoid short trips and turning it off after low rpm driving/not reaching full oil temp IMO.

Recipe has always worked with my 225k e36 and 183k e46.

Or maybe it's a sign to just let her go!

[Tbonem3]

Drive it hard, avoid short trips and turning it off after low rpm driving/not reaching full oil temp IMO.

Recipe has always worked with my 225k e36 and 183k e46.

[BMWahba]

Yea. Who knows really what happened. About 30 miles driven on the car so far, everything seems fine.

[tlow98]

It’s read per bank. There’s only two oxygen sensors. One for the front bank and one for the rear. Changes are made per those sets of cylinders.

[BMWahba]

That could make sense, in that it compensates for other cylinders the ones that were dripping or spraying too much.

[digger]

It probably averages per bank just a guess though

[BMWahba]

An update on my Injector testing... here were the results. Any thoughts on how this corroborates with the symptoms in this thread? Cylinder 1 and 3 were dripping, the rest were in "fair" condition. Cylinder 4 was the one that had low compression...still kinda doesn't add up.

Does anyone know if the ECU averages out the fuel injection across all 6 cylinders or is it read per cylinder?

[BMWahba]

I came here to say this but jet_dogg beat me to it.

In a situation like this swapping in a "known good" part isn't something I would personally do unless it was literally right now in a running car. Say your injector has been sitting on the shelf for 6 months and something has happened to it. You put it in cylinder 3 and nothing changes... because it is also bad now your diagnostics are thrown off.

Instead swap injectors between cylinders and see what happens. IF you confirm the wet cylinder (or misfire) followers the injector THEN put the "known good" injector in it and see if the issue is resolved.

Cyl 4 & 3 are companion cylinders, sometimes something that happens to one affects both.

I understand. Noted. I am sending my set of injectors out to get cleaned anyhow.

[George Hill]

Why don't you swap the injector with one from another cylinder?

I came here to say this but jet_dogg beat me to it.

In a situation like this swapping in a "known good" part isn't something I would personally do unless it was literally right now in a running car. Say your injector has been sitting on the shelf for 6 months and something has happened to it. You put it in cylinder 3 and nothing changes... because it is also bad now your diagnostics are thrown off.

Instead swap injectors between cylinders and see what happens. IF you confirm the wet cylinder (or misfire) followers the injector THEN put the "known good" injector in it and see if the issue is resolved.

Cyl 4 & 3 are companion cylinders, sometimes something that happens to one affects both.

[BMWahba]

Why don't you swap the injector with one from another cylinder?

Not sure what I’d be accomplishing. My cylinder 3 was wet but that was not the low compression cylinder. Logic would have it that cylinder 4 was the one that’d be wet with low compression from a wash out. But again, no clue.

[jet_dogg]

Why don't you swap the injector with one from another cylinder?

[BMWahba]

Yes. I will be sending my injectors out and in the meantime, I put in a spare set which were verified good. I should see the results of the injectors when they get them to rebuild/test to see if they were faulty.

For now, I’ll get the car put together and drive it a bit to see how things do.

[digger]

You could do with an injector service or replacement and then see if the issue persists

[maw1124]

My guess is some o-ring, probably on an injector, is letting fuel wash out Cyl4 when it sits. But that's a guess from WAY far away. I wouldn't suspect a coil or plugs or rings or the cylinder itself.

Seems like a "when it sits" condition only.

maw