[Beunhaas]

Hi guys,

I’ve been reading on here for two years now. A lot of great info, but never posted here simply because the N55 engine ran flawless.

About four months ago the engine started running rough, but never had any codes. Running BM3 stage 2 91 octane tune. Did one more pull to make a log and after that it ran terrible, still no codes.
Got fuel pouring out of the exhaust, had a feeling of a stuck injector.

Flashed back to stock tune, started car and after few seconds a code of misfire on cylinder #5 and injector was shut down.

So replaced the injector, which was indeed stuck wide open as i could blow straight trough it.

After that car ran fine but had some hesitation on WOT. Changed all sparkplugs to new Bosch ZR5TPP33 but still same hesitation on WOT.
Flashed back to stock map, and after a few pulls got misfire at cylinder #5 again. The coilback was quite discoloured so replaced it with a new original BMW one.
On stock map i don’t get any fault codes but sometimes i get a small hesitation, but no fault codes anymore.
On 0+ m2 map i get some hesitations.
And on stage 1 or 2 91 octane maps i get a lot of hesitations and the car shudders quite hard.

Log on stock map:
https://www.bootmod3.net/log?id=6247...90c67276e180a8

Log on m2 map:
https://www.bootmod3.net/log?id=6247...90c67276e180b5

https://www.bootmod3.net/log?id=6247...90c67276e180bc

Log on stage 2 91 octane map (not even possible to make a good log all to redline due to the big hesitations):
https://www.bootmod3.net/log?id=6252...729b0426c79e75

You can see especially in the rpm line the hesitation as the line is not smooth anymore.

Car is a 2014 rwd 8at EWG.
Mods:
BM3
Xhp stage 2
FTP charge pipe
Wagner catted downpipe
Running 93 octane fuel

Any ideas what is going on here?

[XutvJet]

If the injector was stuck open, it could cause the cylinder bore and rings to get washed with fuel thus leading to scouring of the cylinder liner and/or damage to the rings. This damage could result in a loss of compression and/or hot spots in the motor thus leading to misfires and generally wonky performance.

In the B58 motors with the plasma arc coating used as a liner vs the steel liners used in the N55, there have been instances of injectors getting stuck open, washing the cylinders, and destroying the plasma arc coating. The fix? A new B58 short block as the coating is not repaireable.

I'm not saying that full cylinder/ring damage is the source of your issues, but it may be worth doing a compression test.

Hopefully you changed the oil after fixing the injector because all that fuel gets mixed with the oil and negatively impacts its ability to lubricate (i.e., reduces oil grade).

[Info@mad-us.com]

How many miles on the car?

[Beunhaas]

Originally Posted by XutvJet

If the injector was stuck open, it could cause the cylinder bore and rings to get washed with fuel thus leading to scouring of the cylinder liner and/or damage to the rings. This damage could result in a loss of compression and/or hot spots in the motor thus leading to misfires and generally wonky performance.

In the B58 motors with the plasma arc coating used as a liner vs the steel liners used in the N55, there have been instances of injectors getting stuck open, washing the cylinders, and destroying the plasma arc coating. The fix? A new B58 short block as the coating is not repaireable.

I'm not saying that full cylinder/ring damage is the source of your issues, but it may be worth doing a compression test.

Hopefully you changed the oil after fixing the injector because all that fuel gets mixed with the oil and negatively impacts its ability to lubricate (i.e., reduces oil grade).

Definitely going to do a compression test, altough its running butter smooth at idle.
Scouring of the cylinder wall is indeed possible with reduced lubrication from the excessieve fuel. It ran for max 1 min with the injector stuck open so don’t think much if any fuel at all wil contaminate the oil that quickly. Will check the oil.

But if it has hotspots i would expect to see timing corrections at his cylinder, or misfire codes which i don’t. Thats why i cant get my head around whats going on.

One interesting thing that came to mind is that the AFR gets wobly while the hesitation occurs which might indicate misfires. BM3 is know for suppressing missfire codes

[Beunhaas]

Originally Posted by Info@mad-us.com

How many miles on the car?

Hi, car has 100K km so about 62K miles

[Info@mad-us.com]

Originally Posted by Beunhaas

Hi, car has 100K km so about 62K miles

If you drove with that injector stuck open for awhile I would get a compression test done. Just to rule out any engine damage.

[n55david]

Originally Posted by Info@mad-us.com

If you drove with that injector stuck open for awhile I would get a compression test done. Just to rule out any engine damage.

This

You need to check. It could be something serious or minor but you don't know without checking.

I've always seen valvecover leak issues (vacuum problems) cause cylinder issues etc but if you had a stuck open injector, it can be very bad.