[redz06]

Without any warning my unmolested 2011 335i MT6 sedan with 86000 miles developed misfiring today. First I noticed it in the upper reaches of 5th and 6th gears as a slight miss. Later I tried hard acceleration in 1st gear and was rewarded with a half engine symbol in my display. followed by limp home mode.

There were no long cranking sessions or any warning ahead of time, as occurred before my first HPFP was replaced about 25000 miles ago. Is it worth doing any further diagnosis or should I just proceed to order a new HPFP. I am thinking of replacing it myself. Has anyone on the forum done this? I checked the DIYforum and could find nothing on replacing the HPFP for the N55 engine.
Are any non-standard tools required? Is it necessary to do anything to burp the air out of the system before startup?

[Tunafish]

The hpfp is not a normal failure on the n55.. Are you getting codes telling you fuel pump?

[redz06]

I have no way to read error codes, as my Centec OBD code reader does not fit the plug in my car.

My local BMW dealer diagnosed and replaced one HPFP about 4 years and 25000 miles ago. That fixed the problem then. But my N55 is not the only one cited on this forum with HPFP failure. Just because HPFP failures do not happen as frequently on N55 motors as they have on N54 motors does not mean that my current HPFP is fine.

You see the symptoms that I cited in my original post. What do you believe the cause is?

I am reluctant to take my car back to the local dealership, because of past experiences where the service department seems to be "looking for customer-paid work" rather than taking care of design issues with my car.

[Glene]

Originally Posted by Tunafish

The hpfp is not a normal failure on the n55.. Are you getting codes telling you fuel pump?

Early N55 using the same HPFP as the N54. I think they switched to the new style HPFP in 2013.

[Glene]

Are any non-standard tools required? Is it necessary to do anything to burp the air out of the system before startup?[/QUOTE]

The procedure is very much the same as N54.

[Tunafish]

The last n55 pump failure I read about was 2016. Like I said not common.. Could be plugs, coils, fuel injectors, MAF sensors, fuel pump, needs walnut blasted, bad gas, electric gremlins... But fuel pump is a possibility, you can change and if it fixes the issue great, if not then go onto the possibility.

[Tunafish]

The last hpfp revision for the e90 came out in 2010 which was used in cars until 2017.

[redz06]

I had a diagnosis done today which revealed codes set by a bad #5 ignition coil. Glad I did not order a replacement HPFP! I will replace all 6 coils and all 6 spark plugs.

[redz06]

Well I replaced all of the coil packs and installed new spark plugs while I was there. Initially this appeared to resolve the problem, but a 40 mile run yesterday showed that the problem is still there. I got a P300 and a P301 code. I also have a P305 code showing, but that might have been from before replacing the coil packs. Yesterday, I would have to shut off the engine every couple of miles to get the half engine warning to go away. After waiting for a while, the car would restart without the half engine warning and would idle and run well for about a mile, before the misfiring started. Shortly the half engine symbol would come back and the misfiring would become more noticeable. My run back home included about a dozen stops and restarts. All in all not a good day. I tried to erase the codes but this was not successful. Will try again today. After cooling down for a couple of hours, I drove it around the neighborhood for a bit without misfiring, but on pushing the throttle a bit harder I noticed that throttle response was poor, like there was no boost or timing increase. Timing at idle jumps around several degrees.

Any idea what the real problem is?

[Glene]

Originally Posted by Tunafish

The hpfp is not a normal failure on the n55.. Are you getting codes telling you fuel pump?

2011 N55 engine used identical hpfp from N54.

[Tunafish]

Yeah you are right.. But what you are missing is that the n54 had six HPFP revision from 2008 to end of 2010 which than came the seventh revision that was use in n55 until 2016. So while you can use a n54 pump in a n55 why would you want to..

What is the rest of your error codes.. You are missing a number.. It is possible that your issue is hpfp but you could tell pretty easy with right diagnostic tool.. What coil packs did you get?

[redz06]

Originally Posted by Tunafish

Yeah you are right.. But what you are missing is that the n54 had six HPFP revision from 2008 to end of 2010 which than came the seventh revision that was use in n55 until 2016. So while you can use a n54 pump in a n55 why would you want to..

What is the rest of your error codes.. You are missing a number.. It is possible that your issue is hpfp but you could tell pretty easy with right diagnostic tool.. What coil packs did you get?

Coil Packs Bosch 00044X6 Set of 6, latest parts from FCP Euro
Spark Plugs BMW ZR5TPP33. Error codes might have had a 0 or a 00 in front of the P300, 301, 305 etc. I did not believe that was significant. I did not see any codes that I could identify to the HPFP, but still believe that is a possibility.

I erased the codes in the module, but there are still 2 permanent codes recorded for P300 and P305. Good news is that with the external codes erased, the engine is running well again. But I wonder how long that will last.

[Tunafish]

I am not a fan of bosch.. I went that way when the first time i changed my coil plugs.. While they didnt have issues at first, 10k in the coils were shutting off the cars charging circuit once warmed up and once spiked the voltage to +18v. The plugs soon after started miss firing

Went with eldor coils and ngk plugs havent had a issue since.. What you gapped to .025?

[redz06]

I went with .028 per procedure I was following.

[yarin.levy2]

Originally Posted by redz06

Well I replaced all of the coil packs and installed new spark plugs while I was there. Initially this appeared to resolve the problem, but a 40 mile run yesterday showed that the problem is still there. I got a P300 and a P301 code. I also have a P305 code showing, but that might have been from before replacing the coil packs. Yesterday, I would have to shut off the engine every couple of miles to get the half engine warning to go away. After waiting for a while, the car would restart without the half engine warning and would idle and run well for about a mile, before the misfiring started. Shortly the half engine symbol would come back and the misfiring would become more noticeable. My run back home included about a dozen stops and restarts. All in all not a good day. I tried to erase the codes but this was not successful. Will try again today. After cooling down for a couple of hours, I drove it around the neighborhood for a bit without misfiring, but on pushing the throttle a bit harder I noticed that throttle response was poor, like there was no boost or timing increase. Timing at idle jumps around several degrees.

Any idea what the real problem is?

This thread is old but I experience exactly the same. same car same model and year. All 6 coils and plugs were replaced as well.
How have you managed to solve it eventually?