[julianaponte]

Car misfires under heavy throttle. Recently went MHD stage 2+ (Did all preventative maintenance about 6k ago when I rebuilt engine) Car runs perfectly normal but when I put my foot down it starts misfiring and throws an ses light. Sometimes it'll go away by itself and stop misfiring if I drive slow and sometimes I have to turn it off and on again and then it'll stop misfiring. I injectors maybe? Any suggestions?

*Throws cyl 1,2,4 Misfire codes (P0301, P0302, P0304) as well as "O2 sensor No activity Bank 1 Sensor 2 code (P0140)

[924er]

Originally Posted by julianaponte

Car misfires under heavy throttle. Recently went MHD stage 2+ (Did all preventative maintenance about 6k ago when I rebuilt engine) Car runs perfectly normal but when I put my foot down it starts misfiring and throws an ses light. Sometimes it'll go away by itself and stop misfiring if I drive slow and sometimes I have to turn it off and on again and then it'll stop misfiring. I injectors maybe? Any suggestions?

*Throws cyl 1,2,4 Misfire codes (P0301, P0302, P0304) as well as "O2 sensor No activity Bank 1 Sensor 2 code (P0140)

diagnose in this order per cylinder;

plugs, coils, injectors, HPFP, walnut shellblast

https://www.e90post.com/forums/showthread.php?t=631829

[uncle don]

Originally Posted by julianaponte

Car misfires under heavy throttle. Recently went MHD stage 2+ (Did all preventative maintenance about 6k ago when I rebuilt engine) Car runs perfectly normal but when I put my foot down it starts misfiring and throws an ses light. Sometimes it'll go away by itself and stop misfiring if I drive slow and sometimes I have to turn it off and on again and then it'll stop misfiring. I injectors maybe? Any suggestions?

*Throws cyl 1,2,4 Misfire codes (P0301, P0302, P0304) as well as "O2 sensor No activity Bank 1 Sensor 2 code (P0140)

I have exact same issues but bone stock...and same codes.
did you find out a fix? or problem?

[jpauten]

Originally Posted by uncle don

I have exact same issues but bone stock...and same codes.
did you find out a fix? or problem?

Check your plugs and coils first, but if you're having the exact same issue as OP, my guess would be injectors. When the car is cold (hasn't been started in a day or so), pull the plugs and see if they smell like fuel. If they do, go get some index 12 injectors from FCP Euro and at least replace the injectors where the misfires are occurring

[uncle don]

buying plugs and coils today... I have not looked into injectors yet... could injectors cause sluggish low end taking off? surging and or bucking some until maybe drive then clears out? could that be injectors?

[iqraceworks]

Originally Posted by uncle don

buying plugs and coils today... I have not looked into injectors yet... could injectors cause sluggish low end taking off? surging and or bucking some until maybe drive then clears out? could that be injectors?

How old are the plugs and coils that are currently in the car? From everything I've read about N54's......replacing coils and plugs is a must before you even think about modding for power.

I didn't really want to spend the money, but I did new plugs and coils before I started....and haven't had a single issue with misfires. It was money well spent.

[uncle don]

with 117k miles I don't believe coils have never been changed.
paperwork I got says plugs are 33k miles old...

[jpauten]

Originally Posted by uncle don

buying plugs and coils today... I have not looked into injectors yet... could injectors cause sluggish low end taking off? surging and or bucking some until maybe drive then clears out? could that be injectors?

Yes that does sound like injectors. Have you read the codes? There's a chance you'll be able to get away with only replacing a single injector for now

[uncle don]

yes codes are misfires per cylinder and one general misfire... I first had one on cylinder 3 and I put a new coil in and fixed it. then about 24 hours later it did it again and check engine light came on and I had two more cylinder misfires show up....
so im replacing all new coil packs and plugs this weekend to hopefully alleviate that issue.

[lnguyen9152]

Start by moving ignition coils around and seeing if misfire follows

[iqraceworks]

Originally Posted by lnguyen9152

Start by moving ignition coils around and seeing if misfire follows

If they all have 133k miles on them...why waste you time? Replace them all and be done with it.

[relative4]

Originally Posted by iqraceworks

If they all have 133k miles on them...why waste you time? Replace them all and be done with it.

Are you going to pay to replace the perfectly good parts on his car?
Hell, the whole car has 133K miles on it... why waste your time? Replace it and be done with it.

[iqraceworks]

Coils aren't very expensive ($150 for all 6)...if you have a 335i and can't afford coils, you don't need to own a 335i. How long do you think coils last?

Hell....he spent that much on the MHD tune.

[deadwoodluke]

Not trying to hijack this page, but I have identical symptoms but only in cylinder 6. P0306. I've swapped coils and plugs and I'm thinking its the fuel injector, however I have 6 new index 12 injectors. Has anyone heard of this happening with index 12?

[relative4]

Originally Posted by iqraceworks

Coils aren't very expensive ($150 for all 6)...if you have a 335i and can't afford coils, you don't need to own a 335i. How long do you think coils last?

Hell....he spent that much on the MHD tune.

After that doesn't fix the problem, what random parts are you going to advocate wasting money on next?

[jpauten]

Originally Posted by deadwoodluke

Not trying to hijack this page, but I have identical symptoms but only in cylinder 6. P0306. I've swapped coils and plugs and I'm thinking its the fuel injector, however I have 6 new index 12 injectors. Has anyone heard of this happening with index 12?

How new are your injectors? This exact same thing just happened to me, I did everything you did, and it turned out to be my injector.

[iqraceworks]

Originally Posted by relative4

After that doesn't fix the problem, what random parts are you going to advocate wasting money on next?

At 133k miles......it needs them anyways. Wasting your time finding which coils are bad makes about as much sense as trying to find which spark plugs are bad.......with that many miles on them, just replace them.

If it was anything else I would agree with you as far as troubleshooting goes.....but coils and plugs with that many miles on them need to be replaced, all of them.

[uncle don]

I got 6 coils and 6 bosch plugs oem replacements from amazon for $143 shipped for all....not bad if you shop around. same part#'s.
mine has 117k miles on coils, and 33k miles on plugs... so replacing all. if misfires keep happening ill take it to a indi shop and get professional opinion at that point....
I actually had a nice local indi shop here tell me he wouldn't recommend walnut blasting at all on bmw's...im like waaaaaaaaaaaahhhhh....? so everyone has an opinion.

[deadwoodluke]

Originally Posted by jpauten

How new are your injectors? This exact same thing just happened to me, I did everything you did, and it turned out to be my injector.

You know I'm actually not sure, just bought the car. I can tell it has a new HPFP from how it looks and the injectors are all index 12. The coils are from 2018 and eldor according to the manufacture date on them. All the maintenance was done at the dealership. It's actually comforting that you had the same problem on index 12, I thought index 12 fixed all this from happening. I have no problem buying a new injector, just didn't want to waste money if you guys thought it was impossible on an injector so new.

I also have no problems cold starting, in fact I'd say it starts better cold than hot.

[relative4]

Originally Posted by iqraceworks

At 133k miles......it needs them anyways. Wasting your time finding which coils are bad makes about as much sense as trying to find which spark plugs are bad.......with that many miles on them, just replace them.

If it was anything else I would agree with you as far as troubleshooting goes.....but coils and plugs with that many miles on them need to be replaced, all of them.

Repeating nonsense does not make it correct. Coils work until they stop working and do not need to be replaced until then. When they fail, replace them individually.
I've run 7 coil-on-plug cars into high mileage and replaced a total of 3 ignition coils. The idea that coil sets should be replaced proactively is ridiculous, ignorant, and foolish.

The rightmost dash vent in my wife's E90 recently broke. I replaced it for $15. Should I have replaced all the dash vents now in case another breaks later? Would only have cost $60.

[iqraceworks]

So when you replace spark plugs.....do you replace them on an individual basis too? I'm mean.....why be proactive and replace them all at the same time when you can jack around and trouble shoot and replace each one individually when it fails.....

Give me a break.....time is money, it's not worth it to jack around and troubleshoot stuff like that just to save a few bucks.

If an air vent fails...no big deal. Plugs/coils fail....you are stranded and/or risk damaging your motor. Big difference....I guess that's a hard concept for you to grasp.

But do what you want.......nobody cares.

[relative4]

Originally Posted by iqraceworks

So when you replace spark plugs.....do you replace them on an individual basis too? I'm mean.....why be proactive and replace them all at the same time when you can jack around and trouble shoot and replace each one individually when it fails.....

Give me a break.....time is money, it's not worth it to jack around and troubleshoot stuff like that just to save a few bucks.

If an air vent fails...no big deal. Plugs/coils fail....you are stranded and/or risk damaging your motor. Big difference....I guess that's a hard concept for you to grasp.

But do what you want.......nobody cares.

Your equation of plugs and coils demonstrates your lack of understanding of their mechanisms and failure modes.
Plugs degrade gradually due to slow, steady vaporization of the electrodes. Thus they are a scheduled replacement item.
Coils work normally until one of the windings burns up and severs. They fail suddenly, with little or no prior degradation of performance.
I used to keep a spare coil in the trunk. Coils can fail any time, regardless of whether they have 150K miles or 1K miles.
If it takes you more than 5 minutes to verify a failed coil, you're an incompetent mechanic. But I guess we already established that.