Rough Idle and Misfire: Need Help

HT0307 · 05-08-2021, 02:24 AM

Need Help with figuring out what's up with my 09 135 N54. I've got brand new ignition coils, spark plugs, and LPFP. I have a Cylinder 6 Misfire(29D2) that won't go away and has gotten progressively worse. It was originally only under load now the car shakes on start up and idles extremely rough, too rough to drive around. The second code is for Low Pressure Fuel Sensor (29F3). I'm hoping it isn't a bad injector but I'm aware that might be the problem or maybe that sensor but I didn't think a sensor would cause that much of a rough idle and misfire. Any input is appropriated!

Saif2018 · 05-08-2021, 03:47 AM

Quote:

Originally Posted by HT0307

Need Help with figuring out what's up with my 09 135 N54. I've got brand new ignition coils, spark plugs, and LPFP. I have a Cylinder 6 Misfire(29D2) that won't go away and has gotten progressively worse. It was originally only under load now the car shakes on start up and idles extremely rough, too rough to drive around. The second code is for Low Pressure Fuel Sensor (29F3). I'm hoping it isn't a bad injector but I'm aware that might be the problem or maybe that sensor but I didn't think a sensor would cause that much of a rough idle and misfire. Any input is appropriated!

Datalog Log the idle fuel pressures both Rail pressure (HPFP) and LPFP (low pressure fuel pump)

Pull cylinder 6 injectors and smell it, any fuel or oil visible,

If it looks fine, Swap your injector from cylinder 6 to another one, make sure you reseal and see if misfire follows.

HT0307 · 05-09-2021, 01:36 AM

Quote:

Originally Posted by Saif2018

Quote:

Originally Posted by HT0307

Need Help with figuring out what's up with my 09 135 N54. I've got brand new ignition coils, spark plugs, and LPFP. I have a Cylinder 6 Misfire(29D2) that won't go away and has gotten progressively worse. It was originally only under load now the car shakes on start up and idles extremely rough, too rough to drive around. The second code is for Low Pressure Fuel Sensor (29F3). I'm hoping it isn't a bad injector but I'm aware that might be the problem or maybe that sensor but I didn't think a sensor would cause that much of a rough idle and misfire. Any input is appropriated!

Datalog Log the idle fuel pressures both Rail pressure (HPFP) and LPFP (low pressure fuel pump)

Pull cylinder 6 injectors and smell it, any fuel or oil visible,

If it looks fine, Swap your injector from cylinder 6 to another one, make sure you reseal and see if misfire follows.

Update, pulled and swapped out the injector on cylinder 6 and now it's running smooth again.

Saif2018 · 05-09-2021, 05:04 AM

Quote:

Originally Posted by HT0307

Update, pulled and swapped out the injector on cylinder 6 and now it's running smooth again.

Good to hear, do a 3rd gear WOT Datalog and post it here.

05-08-2021, 02:24 AM	#1
HT0307 Private First Class 25 Rep 177 Posts Drives: E82 135i Join Date: Feb 2017 Location: Pensacola, Fl. iTrader: (0) Garage List 2009 135i [0.00]	Rough Idle and Misfire: Need Help Need Help with figuring out what's up with my 09 135 N54. I've got brand new ignition coils, spark plugs, and LPFP. I have a Cylinder 6 Misfire(29D2) that won't go away and has gotten progressively worse. It was originally only under load now the car shakes on start up and idles extremely rough, too rough to drive around. The second code is for Low Pressure Fuel Sensor (29F3). I'm hoping it isn't a bad injector but I'm aware that might be the problem or maybe that sensor but I didn't think a sensor would cause that much of a rough idle and misfire. Any input is appropriated! Attached Images
	Appreciate 0 Tweet Quote