2010 335xi...lots fixed and still missfiring...

[7erfella]

Hello folks, I got a 2010 335xi, manual trans, 70k miles, jb4 tuner, muffler delete and tial bov (just so you guys have all the info)

So the story: car runs rough with tuner on or off or even completely disconnected

I've replaced all spark plugs with new ones from BMW, replaced all coil packs brand new from BMW, had the intake manifold walnut blasted, valve cover and valve cover gasket have also been replaced


And the damn thing is still getting misfiring codes and running rough, mainly misfiring on cylinders 1-3, the hpfp has been replaced through the recall


Another thing I've noticed is I get a hint of fuel smell in the cabin when the heater is running, checked for leaks around the injectors and everything is nice and dry


I just don't really know what else to check, no noticeable boost leaks

[NFerber]

New injectors?

[7erfella]

Haven't touched the injectors yet, is there a way to use INPA or a GT1 system to tell me which one specifically is bad? Or how would I go about testing them BESIDES taking them all out and taking them to a company to be tested

[d21spike]

Haven't touched the injectors yet, is there a way to use INPA or a GT1 system to tell me which one specifically is bad? Or how would I go about testing them BESIDES taking them all out and taking them to a company to be tested

A leaky injector could cause the entire bank to misfire since it would be throwing off the AFR, at least that was the case for me. I'd begin with looking at the index values of your injectors, you want to be on 11's or 12's. That said, you can try looking at the plugs to see if any are wet with fuel or smell like fuel. If you did try to inspect the injector yourself, you would have to replace the decoupling (~$5 at the dealer) ring before reinstalling. Also, you want to be quick since on the tip of the injector there is a seal that will expand. As far as a company that works with our injectors, I have yet to find one.

To answer your question though, no I do not believe there is a way through software to determine a faulty injector.

[7erfella]

Great info! Thank you! Looks like the injector investigation will begin haha

[Critter7r]

You said you had the intake manifold walnut blasted, but did you have the intake valves done too?

[d21spike]

You said you had the intake manifold walnut blasted, but did you have the intake valves done too?

I'm not sure I follow you're logic here .... nothing really gets done to the manifold during a typical blasting as it just comes off to gain access to the valves?

[7erfella]

Yeah sorry guys that's what I meant, I cleaned the valves not the actual manifold, and put in new gaskets as well

[NFerber]

Most people on the forums say that you have to replace a bank of injectors all at the same time, get them coded... Here is something i found over on e90post:

Here is a quote from the most current N54 fuel injector replacement service bulletin: IMPORTANT: Injectors with index 11 and higher have a different calibration and construction than injectors with index 10 and lower. Due to this difference, the injectors with index 11 and higher and injectors with index 10 and lower cannot be mixed on the same engine bank (i.e., cylinders 1-3 or 4-6). Once a bank of injectors is at index 11 or higher, the “bank set replacement” requirement no longer applies. For index 11 injector failures, only replace the failed injector

So it looks like if you have index < 10, then you have to replace the whole bank. So you might as well just replace on cyl. 1-3. If you have 11 or higher, then you might get lucky and just have to replace 1. No I have no idea of how to find just the one that is bad unless you have codes specifically pointing to one cyl instead of the cyl bank. I have seen a post a while ago over on e90post where a guy took them out, leaving them still attached to fuel/electronics, and turned over the car and watched the spray pattern on each to determine a bad injector. That is outside my realm, but maybe something to investigate more.

Hope you find your issue, good luck.

- - - Updated - - -

Another post I found:

"Originally Posted by Jeff@TopGearSolutions
Ive tried myself to play the injector game. I ended up replacing all 6 injectors to index 12 and all head aches were gone.

Pull the spark plug on the offending bank and see how they look.

If they are fouled up it could be an indication that the injector is weak too.

Start with pulling the plugs.

Its hard to tell if an injector is weak unless the spark plug is fouled, the injector tips are gunked up or the injector itself is louder then others.

Only other way to really diagnose injectors is through INPA and it's not bullet proof either but you can look in the "System Status" "Rough Running Idle" area and look at the injectors for anomalies. I feel like im getting a head of myself here so sorry for the rant LOL.

Anyway, if the plugs check out and you really think it's not the injector then it could be a need for walnut blasting on the intake valves."

[7erfella]

Wow! Great info! Thank you! ill start checking everything one of these weekends

[Critter7r]

I'm not sure I follow you're logic here .... nothing really gets done to the manifold during a typical blasting as it just comes off to gain access to the valves?

That was kind of my point, it's the valves that need cleaning ... but I thought maybe his manifold was gunked up and he had that blasted clean too. Either way, I just wanted to see if the actual valves had been cleaned, and OP says they were, so it's all good.

[Reyhan335]

Could be injectors bro.

[7erfella]

As soon as I get some time im gonna pull the plugs and see if any cylinder is worse then another and go from there

[7erfella]

Ok so little update: checked codes again and cleared, then checked again and it comes with the same codes, misfires on cylinder 1-3, so should I replace all 3, or is 1 of them throwing the others off?

[d21spike]

This has already been answered, if 10 and lower you have to replace the bank.


Ok so little update: checked codes again and cleared, then checked again and it comes with the same codes, misfires on cylinder 1-3, so should I replace all 3, or is 1 of them throwing the others off?

[7erfella]

I understand that, but do I have to replace all 3 of those? Or all 6?

[d21spike]

That's up to you, if you can foot the bill I'd do all 6. Basically it's not if but when they leak (that is if you have the older ones). But if you're just looking to fix your issue for now then just do the bank and have them coded.


I understand that, but do I have to replace all 3 of those? Or all 6?

[NFerber]

I understand that, but do I have to replace all 3 of those? Or all 6?

Cylinders 1-3 are 1 bank, cylinders 4-6 are another bank. So if they are index 10 or below, you would replace cylinders 1-3. If 11 or above, you could just replace 1 cylinder.

You could also replace all 6, I don't think that it's necessary and is expensive. But replacing all 6 isn't a bad idea if you have the money.

[7erfella]

Thanks for the help guys, I'll have to figure out what index they are and go from there, money is not really the issue, it's the fact that I've already spent so much that I kinda wanna just replace the bad ones and not all 6 and spend so much money, I'd rather buy some more power miss if possible