[Verbatim]

My car was misfiring in cylinders 5 and 6 and so the dealership decided to replace all the injectors under CPO warranty.
My question is, why are the fuel injectors failing? Aren't they supposed to last the life time of the car?
(and why does it seem like cylinders 5 and 6 are always the most problematic? )

[skinrock]

Just because they replaced them doesn't mean they were failing. I think you would have known if they were all bad. They likely replaced them because they fell under the recall notice.

[Verbatim]

Originally Posted by skinrock

Just because they replaced them doesn't mean they were failing. I think you would have known if they were all bad. They likely replaced them because they fell under the recall notice.

I've actually had the recall done before, so there must have been some reason they needed replacing. (the car wasn't misfiring for no reason)
Does it have to do with carbon build up on the injectors that cause them to spray unevenly?

[cstavaru]

Originally Posted by Verbatim

(and why does it seem like cylinders 5 and 6 are always the most problematic? )

First check if the misfires disappeared...

[blisstik]

They may have replaced them so they can get paid for the labor.

[Verbatim]

Originally Posted by blisstik

They may have replaced them so they can get paid for the labor.

that's great for me haha
so injectors never fail?

[GeorgiaTech335coupe]

I'd imagine they have a very low tolerance for error, which can be somewhat supported by the fact they need to be coded which I believe is to accomodate minor manufacturing inconsistencies.

If it makes you feel better, I have only 60k miles and cyl 1 is on its 4th inj, cyl 2,4,5,6 are on their 3rd injector and cyl 3 is on its 5th injector.

[Verbatim]

Originally Posted by GeorgiaTech335coupe

I'd imagine they have a very low tolerance for error, which can be somewhat supported by the fact they need to be coded which I believe is to accomodate minor manufacturing inconsistencies.

If it makes you feel better, I have only 60k miles and cyl 1 is on its 4th inj, cyl 2,4,5,6 are on their 3rd injector and cyl 3 is on its 5th injector.

were those all replaced under warranty? I can't imagine someone would replace 14 injectors out of pocket

[GeorgiaTech335coupe]

Originally Posted by Verbatim

were those all replaced under warranty? I can't imagine someone would replace 14 injectors out of pocket

only the 1st replacement set was under warranty. I ponied up the rest for the following 9. Had my warranty voided. Twice.

[GeorgiaTech335coupe]

Originally Posted by GeorgiaTech335coupe

only the 1st replacement set was under warranty. I ponied up the rest for the following 9. Had my warranty voided. Twice.

I've also paid out of pocket for: water pump, many coils, lpfp, hpfp, battery, few pulleys, broken drive shaft, probably some other stuff I can't remember.

Car has cost me a lot of money, but I drive it harder than most.

[psmitty95]

I just bought one injector to fix my misfires in cylinder 3. I wanted to do all 6 but don't have the money to do that right now. I should also probably get a carbon cleaning soon since i'm at 51k miles...

[Verbatim]

I think the rare misfires could have been caused by my spark plugs... 47k miles and i haven't changed them yet

[dicostal]

Originally Posted by GeorgiaTech335coupe

I'd imagine they have a very low tolerance for error, which can be somewhat supported by the fact they need to be coded which I believe is to accomodate minor manufacturing inconsistencies.

If it makes you feel better, I have only 60k miles and cyl 1 is on its 4th inj, cyl 2,4,5,6 are on their 3rd injector and cyl 3 is on its 5th injector.

WTF man that does not make me feel better at all.

My car has 60k miles, and had an issue with injector once and they replaced only the faulty injector under CPO. I love my car and it is tune with FBO and I drive it hard when i want but not everyday. Its been pretty reliable thus far, but you are freaking me out...

[GeorgiaTech335coupe]

Originally Posted by Verbatim

I think the rare misfires could have been caused by my spark plugs... 47k miles and i haven't changed them yet

From my experience, this is the differences I've seen in misfires caused by different components (don't take this as the gospel, just some tendencies I've seen):

1. If you lug your engine in 3rd and the misfires happen right away, it was usually a bad coil.

2. If you lug your engine in 3rd and the misfires happen after being in WOT for a little bit after full boost, then it was usually a bad injector (majority of the causes for my misfires).

3. If the car only misfires at really high rpm when going WOT, then it was the spark plugs. (rarely ever was the case).

[GeorgiaTech335coupe]

Originally Posted by dicostal

WTF man that does not make me feel better at all.

My car has 60k miles, and had an issue with injector once and they replaced only the faulty injector under CPO. I love my car and it is tune with FBO and I drive it hard when i want but not everyday. Its been pretty reliable thus far, but you are freaking me out...

My car has been an anomoly compared to others with this misfire bug. I have had it come up so many times. I've been FBO+meth for over 2 years and meth will definitely cause the misfire bug to rear its head a lot easier.

Overall, I haven't had any major issues. Never had a lpfp or hpfp go out on me in 60k miles (replaced both becuase I wanted to). I did break my drive shaft, but I drag race my car A LOT. Well over 300 1/4 mile passes.

[psmitty95]

Originally Posted by GeorgiaTech335coupe

From my experience, this is the differences I've seen in misfires caused by different components (don't take this as the gospel, just some tendencies I've seen):

1. If you lug your engine in 3rd and the misfires happen right away, it was usually a bad coil.

2. If you lug your engine in 3rd and the misfires happen after being in WOT for a little bit after full boost, then it was usually a bad injector (majority of the causes for my misfires).

3. If the car only misfires at really high rpm when going WOT, then it was the spark plugs. (rarely ever was the case).

Mine was the 2nd one. I realized it was for sure misfires since my spark plugs were replaced at 49k and I swapped coils but the misfire didn't follow. Here's a thread I made back when I was trying to figure it out http://www.e90post.com/forums/showthread.php?t=749067 . I have the injector in my garage and it's getting installed this weekend along with many other things.

[dicostal]

Originally Posted by GeorgiaTech335coupe

My car has been an anomoly compared to others with this misfire bug. I have had it come up so many times. I've been FBO+meth for over 2 years and meth will definitely cause the misfire bug to rear its head a lot easier.

Overall, I haven't had any major issues. Never had a lpfp or hpfp go out on me in 60k miles (replaced both becuase I wanted to). I did break my drive shaft, but I drag race my car A LOT. Well over 300 1/4 mile passes.

I drive my car hard, but I try not to take it to the track for 1/4 mile runs. I did in the past and blew a transmission doing so, granted it was a fwd car and i did about 15 passes. So I try to be a bit more careful with this car. I have everything on my care but Meth, been debating getting meth...

I think I will go bigger turbos before I go Meth, I also use the fuel injector cleaner every 6 months, I know many say it does nothing but I feel a difference every time I use it.

[Juiced46]

Originally Posted by Verbatim

My car was misfiring in cylinders 5 and 6 and so the dealership decided to replace all the injectors under CPO warranty.
My question is, why are the fuel injectors failing? Aren't they supposed to last the life time of the car?
(and why does it seem like cylinders 5 and 6 are always the most problematic? )

Injectors do not last the lifetime of a vehicle. This isn't just for BMW, this is for all manufacturers. Injector failures are not uncommon on all platforms across the board.

Originally Posted by Verbatim

I've actually had the recall done before, so there must have been some reason they needed replacing. (the car wasn't misfiring for no reason)
Does it have to do with carbon build up on the injectors that cause them to spray unevenly?

It has nothing to do with carbon buildup on the injector. The injector does not get carbon build up on it.

Originally Posted by blisstik

They may have replaced them so they can get paid for the labor.

That is totally untrue. I will tell you why the car got 6 injectors. The test plan for misfires is very specific when using the BMW equipment. It looks at a few different variables. Some are symptoms (i.e gas smell etc), production date and what part # injector is in the engine. From there the tester will tell you based on the diagnosis which injectors to replace. Typically if you have 1 or 2 cylinders misfiring on the same bank, the tester will have you replace ALL injectors on that bank. It will then ask what part # injectors the opposing bank has installed. If its an older # then it has you replace that whole bank as well. It has nothing to do with the dealer trying to get more labor nor the tech doesnt know what he is doing so he just "shotguns" 6 injectors into the car.

Originally Posted by GeorgiaTech335coupe

I'd imagine they have a very low tolerance for error, which can be somewhat supported by the fact they need to be coded which I believe is to accomodate minor manufacturing inconsistencies.

If it makes you feel better, I have only 60k miles and cyl 1 is on its 4th inj, cyl 2,4,5,6 are on their 3rd injector and cyl 3 is on its 5th injector.

They needed to be coded because each injector has a unique "flow rate" so to speak. They have Piezo crystals inside of them and each injectors tolerance is slightly different. So the DME needs to be coded to know which injector is in which cylinder based on the # stamped on the injector.

Your cyl #1 issue may also be a carbon buildup issue on the intake valves. This can cause misfires and misdiagnosed as an injector problem at times.

Originally Posted by psmitty95

I just bought one injector to fix my misfires in cylinder 3. I wanted to do all 6 but don't have the money to do that right now. I should also probably get a carbon cleaning soon since i'm at 51k miles...

Did you have the injector recall done? If so do you know how many injectors they replaced? ( you do not automatically get 6 new ones FYI) Also if you need a carbon cleaning done shoot me a PM I can help you out.

[Verbatim]

Originally Posted by Juiced46

Injectors do not last the lifetime of a vehicle. This isn't just for BMW, this is for all manufacturers. Injector failures are not uncommon on all platforms across the board...

thanks for giving the first real answer

[phil200tdi]

Haven't the problems been more electrical? Ie the piezo crystals fail?

[E90Company]

Originally Posted by psmitty95

Mine was the 2nd one. I realized it was for sure misfires since my spark plugs were replaced at 49k and I swapped coils but the misfire didn't follow. Here's a thread I made back when I was trying to figure it out http://www.e90post.com/forums/showthread.php?t=749067 . I have the injector in my garage and it's getting installed this weekend along with many other things.

Should have gotten a warranty Peter

[psmitty95]

Originally Posted by E90Company

Should have gotten a warranty Peter

Hahaha I wish I did... It was hard enough finding a manual 335 that was AWD though so adding a CPO to that would have made it near impossible. I had been looking for months and got fed up and just took the risk... Kinda regret it now