[MLars]

Hi all, just picked up a 2008 335i with 101k miles. Cars was having misfiring issues (cyl 1 misfire) so I replaced the plugs and coils per recommendation from this forum. It already has index 12 injectors, although I'm not sure when they were done. Ran a bottle of Techron fuel system cleaner through it too. The car runs better but still misfires slightly, and today I was able to get the SES light to come on again. Pulled over and plugged in my code reader, came up with cyl 6 misfire. Aside from going over half throttle in gears 3 through 6 the car runs great. No cold start idle issues to speak of. Dealer also confirmed "all recalls have been addressed," so not sure if that includes the HPFP. Any suggestions/experience with this? From the reading I've done it seems to be either HPFP or carbon buildup, do these symptoms sound like this?

Thanks in advance,

Matt

[bimmerguy1210]

Just because the recall has been done on the hpfp, doesn't mean it won't fail again. My 2010 ''recalled'' hphp with 70k miles failed last month. I got misfires and cylinder shutdown in the upper rpm range as well. This would be my prime suspect, and if you haven't done a walnut blast yet then do that as well although it would be a stretch that it's the cause.

A datalog will be very beneficial.

[MLars]

Originally Posted by bimmerguy1210

Just because the recall has been done on the hpfp, doesn't mean it won't fail again. My 2010 ''recalled'' hphp with 70k miles failed last month. I got misfires and cylinder shutdown in the upper rpm range as well. This would be my prime suspect, and if you haven't done a walnut blast yet then do that as well although it would be a stretch that it's the cause.

A datalog will be very beneficial.

Awesome, thanks for the advice. I figured it would probably be the fuel pump. I can data log with MHD right?

[b92]

Likely culprit is usually a spark plug or coil. If you're not short on money I recommend replacing all of these, it costs a little over $200 and if you order from FCP Euro you will get a lifetime warranty with them.

If you want to go the cheap route, try swapping the spark plug from cyl 6 with a spark plug in another cyl to see if the misfire code follows the spark plug or stays at cyl 6. If it moves then you'll need a new spark plug.

If it stays, try swapping your cyl 6 coil pack with another cyl. If the misfire code moves then it's your coil pack. If you need to replace a coil then you should replace all of the coils in that same bank ('bank 1' is cyls 1,2,3 and 'bank 2' is cyls 4,5,6).

If the misfire stays in 6 then you can be looking at a faulty injector ($$$) or simply carbon buildup. I would get your intake valves walnut blasted first since this is the cheaper of the two and is a maintenance that should be completed every 40k miles or so. Carbon buildup can also be noticed when idling- take a close look at your RPMs when idling and if they're bouncing around then you probably need to have your intake valves walnut blasted.

[bimmerguy1210]

Originally Posted by MLars

Awesome, thanks for the advice. I figured it would probably be the fuel pump. I can data log with MHD right?

Yes, you can!

[MLars]

Originally Posted by b92

Likely culprit is usually a spark plug or coil. If you're not short on money I recommend replacing all of these, it costs a little over $200 and if you order from FCP Euro you will get a lifetime warranty with them.

If you want to go the cheap route, try swapping the spark plug from cyl 6 with a spark plug in another cyl to see if the misfire code follows the spark plug or stays at cyl 6. If it moves then you'll need a new spark plug.

If it stays, try swapping your cyl 6 coil pack with another cyl. If the misfire code moves then it's your coil pack. If you need to replace a coil then you should replace all of the coils in that same bank ('bank 1' is cyls 1,2,3 and 'bank 2' is cyls 4,5,6).

If the misfire stays in 6 then you can be looking at a faulty injector ($$$) or simply carbon buildup. I would get your intake valves walnut blasted first since this is the cheaper of the two and is a maintenance that should be completed every 40k miles or so. Carbon buildup can also be noticed when idling- take a close look at your RPMs when idling and if they're bouncing around then you probably need to have your intake valves walnut blasted.

Thank you for the detailed reply, I just did all plugs and coils less than 500 miles ago (from FCP Euro). And due to the fact that I've gotten it on cylinder 1 and 6, I'm beginning to rule out an ignition (plugs, coils, injectors) issue and am leaning towards the fuel pump. I do agree with you about the intake valves, I'm probably due for a cleaning on those anyways. Would an issue like these be the intake valves though? Idle is perfectly smooth with absolutely no oscillations.

[MLars]

Originally Posted by bimmerguy1210

Yes, you can!

Just another thing to buy haha, good thing I budgeted for repairs when I bought this thing. I'll get on ordering that. What am I looking for in the log, lack of fuel pressure or cut off?

[HKD126]

Pull the intake manifold off and check out the intake valves. Will take you no more than 45 minutes if you’ve never done it, requires very basic tools and will cost you nothing to diagnose. Start there.

[MLars]

Originally Posted by HKD126

Pull the intake manifold off and check out the intake valves. Will take you no more than 45 minutes if you’ve never done it, requires very basic tools and will cost you nothing to diagnose. Start there.

I've got an appointment for an hour at a DIY garage on Saturday, I'll try to do it then while I'm changing my coolant (coolant flange broke off, replaced with aluminum one and filled with water). Just moved to Florida for a job and don't have any of my tools from back home, so it's been difficult to find time to work on my car, especially without a garage.

[SSW]

Originally Posted by MLars

Thank you for the detailed reply, I just did all plugs and coils less than 500 miles ago (from FCP Euro). And due to the fact that I've gotten it on cylinder 1 and 6, I'm beginning to rule out an ignition (plugs, coils, injectors) issue and am leaning towards the fuel pump.

FWIW, when I replaced all of the coils in my 335i E90, one of them was bad.

If you haven't done it already, try swapping one of your other coils w/the one on #6. If the misfire "moves" to the one w/the coil that was on #6, then you know that is the problem.

Buy another coil to replace the bad one.

[MLars]

Ok guys, got my cable in from BMS last week and was finally able to get a couple logs. Ran from 1st through 3rd gear. Did these on a two lane back road so would've been dangerous to go faster than that.

https://drive.google.com/drive/folde...vn?usp=sharing

[turbohugh]

Originally Posted by MLars

Ok guys, got my cable in from BMS last week and was finally able to get a couple logs. Ran from 1st through 3rd gear. Did these on a two lane back road so would've been dangerous to go faster than that.

https://drive.google.com/drive/folde...vn?usp=sharing

Upload the logs to data zap.ne and then go to n54tech.com a lot more traffic for logs there

[MLars]

Originally Posted by turbohugh

Upload the logs to data zap.ne and then go to n54tech.com a lot more traffic for logs there

Ok thanks, I'll try to do that after work

[dcorn]

I had a misfire with no code, pushed it hard and finally got a "cyl 5 misfire" code. New plugs solved that and made the car run much better. Still had a bit of roughness so I got the valves cleaned and the car ran perfectly after that.

[MLars]

Originally Posted by dcorn

I had a misfire with no code, pushed it hard and finally got a "cyl 5 misfire" code. New plugs solved that and made the car run much better. Still had a bit of roughness so I got the valves cleaned and the car ran perfectly after that.

Thanks for the info. Ya I've done plugs and coils, and based on my logs my fuel pressure looks great. Think I'll go ahead and get the valves cleaned, it's most likely due for it anyways