This is mind boggling e9x master minds way in please !!!!

So I am going to keep this short until questions come in. Never seen or heard anything g like this on a e9x M3 before. So the other night driving not hard just cruising and the car starts to mis fire something crazy. Immediately you turn and bring the car back home. Car is towed to the Indy the next morning. Car is throwing codes for a bad coil on cylinder 7. Replaced coil and car is still mis firing. Compression test is now performed. Compression test results in zero on cylinder 7. Camera is then snaked into this cylinder. The result is a hole in piston # 7. . Rod bearings were done 3000 miles ago and throttle actuators 1500 miles ago. Has anyone ever seen this or know what could cause it???? Shop is thinking the injector failed

Gotta be pretty lean to melt a hole in a piston dome. Did they induce some sort of vacuum leak at the cylinder 7 throttle body when the throttle actuators were replaced? 1500 miles seems like a suspicious interval prior to this failure. Surprised there were no other codes leading up to the holed piston though. Severe detonation could conceivably hole a piston, but that should be detected by the ionic knock sensing.

One other cause for piston crown damage is of course contact with a valve, but that generally destroys the valve rather quickly.

Beemdog wrote

Gotta be pretty lean to melt a hole in a piston dome. Did they induce some sort of vacuum leak at the cylinder 7 throttle body when the throttle actuators were replaced? 1500 miles seems like a suspicious interval prior to this failure. Surprised there were no other codes leading up to the holed piston though. Severe detonation could conceivably hole a piston, but that should be detected by the ionic knock sensing.

One other cause for piston crown damage is of course contact with a valve, but that generally destroys the valve rather quickly.

Good point but how could I prove they induced a vacuum leak? I do too find it strange that this happened so soon after the repair. Im just at a loss and would want to trouble shoot this before I go and rebuild an engine to correct whatever caused this

Broken spring then loose keepee then dropped valve then broken valve then broken piston?

pbonsalb wrote

Broken spring then loose keepee then dropped valve then broken valve then broken piston?

That could be a possibility as well:confused0068:

In this post from the place that did your rod bearings:
http://www.m3post.com/forums/showthread.php?t=1262765

they wrote "Notice Cylinder 7 Upper is down to the copper"

Could there already have been an issue with Cylinder 7 back then that was missed?

Or is it just a coincidence that Cylinder 7 had the worst looking bearing and now your piston on the same cylinder is bad?

This is everyone's worst nightmare, sorry for your loss! Did you have any other symptoms leading up to the failure? What mods does the engine have? I'm no expert but theres probably several things that could cause this such as detonation, water/coolant in the engine, broken timing chain/valvetrain, loss of oil, etc. Hopefully your shop can troubleshoot further and track down the root cause for you or something else is likely to turn up during the tear down. How much is the rebuild going to run?

Mr. BMW wrote

In this post from the place that did your rod bearings:
http://www.m3post.com/forums/showthread.php?t=1262765

they wrote "Notice Cylinder 7 Upper is down to the copper"

Could there already have been an issue with Cylinder 7 back then that was missed?

Or is it just a coincidence that Cylinder 7 had the worst looking bearing and now your piston on the same cylinder is bad?

This seems more likely to be the issue the more I think about it. Anybody know the likelihood that this is in fact a spun bearing this recent after the rod bearing replacement ?

M3amigos wrote

This is everyone's worst nightmare, sorry for your loss! Did you have any other symptoms leading up to the failure? What mods does the engine have? I'm no expert but theres probably several things that could cause this such as detonation, water/coolant in the engine, broken timing chain/valvetrain, loss of oil, etc. Hopefully your shop can troubleshoot further and track down the root cause for you or something else is likely to turn up during the tear down. How much is the rebuild going to run?

This is worse than a nightmare especially when you did preventative maintenance on the Rod bearings right before this as well as throttle actuators. Only mod on the car is test pipes and exhaust. There were no symptoms leading up to this. Car was running cruising and it just started to misfire. Turned around brought it back home had it towed to the shop next morning. Shop thinks likely cause was a failing injector. So the injectors are being sent out to determine that then go from there. Doesn't make sense rebuilding or getting a transplant motor without knowing the cause. This was almost certainly a fueling issue

E92NJM3 wrote

This is worse than a nightmare especially when you did preventative maintenance on the Rod bearings right before this as well as throttle actuators. Only mod on the car is test pipes and exhaust. There were no symptoms leading up to this. Car was running cruising and it just started to misfire. Turned around brought it back home had it towed to the shop next morning. Shop thinks likely cause was a failing injector. So the injectors are being sent out to determine that then go from there. Doesn't make sense rebuilding or getting a transplant motor without knowing the cause. This was almost certainly a fueling issue

Yours is the second e9x car that I've heard with a possible fuel injector failure.

redpriest wrote

Yours is the second e9x car that I've heard with a possible fuel injector failure.

Really. I would love for that person to chime in and tell me about it. Also the shop is saying this could become a wide spread issue with the higher mileage cars as more and more ppl are crossing over into the 80k mileage range. Should injectors and fuel pump in which the fuel filter is built into be changed around 75-80 k

E92NJM3 wrote

Really. I would love for that person to chime in and tell me about it. Also the shop is saying this could become a wide spread issue with the higher mileage cars as more and more ppl are crossing over into the 80k mileage range. Should injectors and fuel pump in which the fuel filter is built into be changed around 75-80 k

http://www.m3post.com/forums/showthread.php?p=20236769#post20236769

To the OP sorry for your loss, it is a nightmare.

Seems like far too much of a coincidence that it's the same cylinder especially after changing to new bearings for only 3k miles.

This may point to an underlying root cause to these failures.

Mr. BMW wrote

In this post from the place that did your rod bearings:
http://www.m3post.com/forums/showthread.php?t=1262765

they wrote "Notice Cylinder 7 Upper is down to the copper"

Could there already have been an issue with Cylinder 7 back then that was missed?

Or is it just a coincidence that Cylinder 7 had the worst looking bearing and now your piston on the same cylinder is bad?

wow..what are the odds man...sorry for your loss

Test pipes require a tune, do they not? Might have been running too lean.

Did you bring the car back to the place that did your bearings and if so what do they think?

Mr. BMW wrote

Did you bring the car back to the place that did your bearings and if so what do they think?

The culprit has been found. After injectors were tested the injector for cylinder #7 failed. Stuck 90% shut. Failing injectors is now another weak point of this car

E92NJM3 wrote

Failing injectors is now another weak point of this car

Your car, or all M3s because of this one failure?

E92NJM3 wrote

The culprit has been found. After injectors were tested the injector for cylinder #7 failed. Stuck 90% shut. Failing injectors is now another weak point of this car

So the cylinder was only getting 10% fuel which was cause detonation and that lead to the failure?? Wouldn't the knock sensor prevent that from happening?

javarithms wrote  

E92NJM3 wrote

The culprit has been found. After injectors were tested the injector for cylinder #7 failed. Stuck 90% shut. Failing injectors is now another weak point of this car

So the cylinder was only getting 10% fuel which was cause detonation and that lead to the failure?? Wouldn't the knock sensor prevent that from happening?

Would this not set a fuel trim code? P0171? Theres gotta be more to this story