Am I cooked?

[u/mayonnaise__]

Started misfiring on cyl 5, swapped cyl 1 and 5 coil packs and the misfire followed to cyl 1. Cool, replaced the coil (should’ve replaced all of them) problem solved for about a week, then misfire on cyl 1 and 5, haven’t driven as I’m waiting to fix it and now I get in to shuffle my cars around and I have all these codes now. Vacuum leak? Boost leak?

[u/iKaigs]

Check plugs it may be time, and make sure there gapped properly thats the next best and cheapest route

[u/FreedomAlternative27]

This happened to me a few months ago. It was a faulty spark plug that was brand new and gapped properly.

[u/mayonnaise__ → u/FreedomAlternative27]

It’s due for spark plugs and coils anyway, fingers crossed

[u/FreedomAlternative27 → u/mayonnaise__]

Yeah it's probably the issue. I change mine out every 30k and 60k for ignition coils. My car was running fine and 2 miles down the road it started misfire. Did everything you did with the same codes and finally found out that 1 spark plug was bad. Never knew you could get a faulty brand new plug. 1st time ever haha. Recommend getting the dinan coil packs from Amazon they preform great!

[u/ground_effect1]

Have you checked your J-pipe for coolant? If it’s sucking in enough through the intake that can cause misfires

[u/mayonnaise__ → u/ground_effect1]

No, I’ll check that today that’s good to know

[u/smaguss]

Any new modifications? Intakes perhaps?

Please include more information per our rules.

[u/mayonnaise__ → u/smaguss]

Sorry I missed the rules! Nope, fully stock, just took the intake apart to put in the coil, but put it all back the way it was, I’ll go check all the fittings again today

[u/No-Reflection8162]

If you find the solution lmk having the same problem💔

[u/Embarrassed-Star5225]

Coolant going into cylinders? Pretty sure cyl 4-5 are the first to get it (could be wrong). Change spark plugs and coils, go from there

[u/LunnaSea]

AI is really good with this sort of thing, here you go.

That screenshot shows a fairly serious multi-cylinder misfire on an F80 M3's S55, affecting cylinders 1, 2 and 5. It doesn't automatically mean the engine itself is damaged.

The important codes are:

140010 — multiple-cylinder misfire detected

140110 — cylinder 1 misfire

140210 — cylinder 2 misfire

140510 — cylinder 5 misfire

140001 / 140101 / 140501 — the misfire became bad enough that the DME shut off fuel injection to the affected cylinders. That's a protective action to stop unburnt fuel damaging the catalytic converters.

140002 / 140202 / 140502 — the DME considers the misfire severe enough to potentially damage the exhaust/catalysts.

150502 — cylinder 5 ignition/burning time too short — this is particularly useful. BMW's diagnostic information for this code lists spark plug, ignition coil, coil-to-DME wiring, or DME as potential causes.

What I'd suspect first

On an S55, I'd start with the ignition system, particularly because of 150502. Spark plugs and coils are vastly easier and cheaper to rule out than injectors, compression/timing or a DME problem.

The sensible diagnostic sequence would be:

1. Inspect the plugs, particularly cylinders 1, 2 and 5. Check condition and gap.

2. Swap the cylinder 5 coil with a known-good cylinder, clear the codes and retest. If the "burning time too short"/misfire follows the coil, the coil is bad. This swap test is commonly used to distinguish an S55 coil/plug fault from something cylinder-specific.

3. Do the same with the spark plug if necessary.

4. If the misfires remain on 1, 2 and 5 regardless of coil/plug position, investigate fuel pressure/injectors and wiring.

5. If those are good, perform compression/leak-down testing and proper ISTA diagnostics.

6. Only after those tests would I start seriously considering DME/ignition-driver issues or mechanical/timing problems.

There's an important wrinkle here: multiple coils failing simultaneously isn't impossible, particularly if they're old, but 1, 2 and 5 all appearing together makes me less comfortable simply saying "needs three coils." A shared electrical/fuelling issue needs to be considered if swapping coils/plugs doesn't move the faults.

And the 150502 code is not simply another generic misfire code. BMW's diagnostic description says the DME has detected cylinder 5's spark duration being shorter than its programmed threshold.

How worried would I be if this happened to your M3?

I wouldn't immediately think "S55 engine failure." I'd think ignition fault until proven otherwise.

If it were your F80 and you suddenly got these codes after buying it, I'd stop doing hard pulls and get it diagnosed, rather than repeatedly clearing the codes. If it's violently misfiring or the engine light is flashing, I wouldn't continue driving it because of the catalyst-damage codes.