THE M3 IS GETTING THE ANRI BUILD TREATMENT - Blown headgasket to build thread

[sapote]

I think the problem will be back after the plugs fouled again. Modern engines don’t foul plugs for no reason.

[ChapterM3]

I hear you guys, let me lay this out clearly so we're all on the same page, here's what happened today -
- The shop did NOT recommend doing a leak-down test right away, they recommended checking the plugs first, and then seeing if the codes clear for the misfire. If the car kept misfiring, they then said to move on to do a leak down.
- When they pulled the plugs, they reported them as all 6 being fouled and recommended changing them to see if that clears the problem
- They installed 6 new OEM plugs and reported that the cylinder misfires were clear, and the car was performing as normal, with no codes coming back
- Shop did not recommend moving forward with leak down at this time unless I absolutely wanted to

With that said I felt comfortable to say that it was in fact the fouled plugs, considering when they replaced them, the codes did not come back.

Am I missing anything further? If you all highly recommend I really have this leak down done I'm open to hearing your thoughts - from my end right now after going through this diagnosis with them, I don't see how else it could only be the plugs given the scenario I just laid out above - but again, I'm open to hear your thoughts!

Thank you!

[Arith2]

The shop was spot on for recommending a leakdown. If your skills aren't there to do it, don't put off the problem thinking you're going to DIY this. It's a gamble that could cost you a $5000 engine.

[sapote]

[B]They're going to check to make sure that the plugs did the trick and the cylinder misfires are gone - and I think if that comes back then I would not perform the leak-down test now. I would however learn more about doing said test myself, so that I can do it at my own leisure and not have to worry if I'm damaging the motor.

Sorry but I don't think new plugs will fix the problem. Should have the leak down test done instead.

I just don't see the point of having the shop just change the plugs.

[ChapterM3]

Why not have them do the leak down while the plugs are out? Getting to that point is like 75% of the work

It's a good point, but I decided otherwise as I'd like to learn the process and then do it myself when I have the time, so I can continue maintaining it on my own terms

[heinzboehmer]

Why not have them do the leak down while the plugs are out? Getting to that point is like 75% of the work

[ChapterM3]

Update - Brought it over to the M Shop - a local, well-known M-focused shop in the LA area - And brought it in for a leak down. While going through the car they noted that the car had added a cylinder to the misfire: Cyl 3, 4 and 5 were miss firing and it was cutting fuel to those cylinders. They recommended pulling the plugs to see what was happening and then futerh assessing if the car would need a leak-down test. Turns out all 6 plugs were fouled - I'm assuming prematurely worn from the e85 used while these plugs were in. So they are replacing the plugs with new OEM ones I brought with the car that I had bought a few months back from FCP.

They're going to check to make sure that the plugs did the trick and the cylinder misfires are gone - and I think if that comes back then I would not perform the leak-down test now. I would however learn more about doing said test myself, so that I can do it at my own leisure and not have to worry if I'm damaging the motor.

Any further thoughts, feel free to share y'all, thank you!

[sapote]

Thank you for your input - so considering what you're saying, would a bad HG disappear after the engine warmed back up again?

The leak could seal itself with the warm/hot head expanded. Not necessarily it's your case but it's a possibility based on the symptom.

[ChapterM3]

1. I don't think it's the bad coils, as bad coils issue should not disappear a few minutes later. Yes, I would do a leak down test.
2. It must be a mistake as these cars idle at around 850rpm. 500 rpm is too low.

Thank you for your input - so considering what you're saying, would a bad HG disappear after the engine warmed back up again?

[sapote]

1. CEL - Misfire codes P0300, P0304,P0305 (multiple cylinder misfire, Cyl 4 and Cyl 5 misfire) when I started my car after it was only sitting for about 15 minutes, so the engine was still warm.
2. Car does not misfire while driving, and once driven, idle goes back down to its normal 500rpm

1. I don't think it's the bad coils, as bad coils issue should not disappear a few minutes later. Yes, I would do a leak down test.
2. It must be a mistake as these cars idle at around 850rpm. 500 rpm is too low.

[ChapterM3]

What tune were you or the previous owner using for the E85? What injectors? E85 will quickly lean out and damage an engine on stock injectors. The S54 is tough but that’s a huge red flag. Not trying to discourage but rather prepare you for more than a simple coil change.

ProFlex Commander kit - https://www.advancedfueldynamics.com...bmw-e46-m3-s54
Edit: Stock injectors :-/, then when kit was taken out, stock injectors were replaced with new ones

Car has not run e85 for about 20k now and has had zero miss-fire issues besides this

[Arith2]

Got it thank you for this rec - Definitely don't hear marbles rattling, so that's a good sign - but still want to make sure with a leak down. One note I forgot to add is that the car did run e85 for about 15k miles, and I'm wondering if that might have fowled the plugs pre-maturely. Worth taking a look at for sure when they're doing the leak down. Will report back next week when I get the results (car won't be driven until leak down is performed)

What tune were you or the previous owner using for the E85? What injectors? E85 will quickly lean out and damage an engine on stock injectors. The S54 is tough but that’s a huge red flag. Not trying to discourage but rather prepare you for more than a simple coil change.

[ChapterM3]

With those 3 codes I don't recommend you drive it at all and go directly to doing the leak down test.
Most people call pinging knocking and sometimes describe it as marbles rattling in the engine.

Got it thank you for this rec - Definitely don't hear marbles rattling, so that's a good sign - but still want to make sure with a leak down. One note I forgot to add is that the car did run e85 for about 15k miles, and I'm wondering if that might have fowled the plugs pre-maturely. Worth taking a look at for sure when they're doing the leak down. Will report back next week when I get the results (car won't be driven until leak down is performed)

[Halftim3]

With those 3 codes I don't recommend you drive it at all and go directly to doing the leak down test.
Most people call pinging knocking and sometimes describe it as marbles rattling in the engine.

[ChapterM3]

Do you hear pinging in the 2k - 3k rpm range when driving? I would do a leakdown test to confirm the headgasket isn't blown between those cylinders.
i had those same codes at idle a few years ago with fresh ngk plugs and updated bosch coils, but it was the headgasket. Got it fixed and those codes never returned.

-Mike

You know, I did notice a ping, a singular ping, a couple of separate times in that range - it was very faint, and more like a typical vanos-type sound (Vanos has been all replaced 20k ago, still get the normal noises), but now that you mention it I did notice something. Only a singular ping though.

Can you describe more of what I should listen for? I listen for every little sound and notice every little sound, so the more you describe the better I can listen if that makes sense - What other symptoms could I look for before doing a leak-down test?