[mrb3is]

[/FONT]Hello all. I have a 2007 E92 with the N54 motor. I have been having the typical injector problems, and have been replacing them as they went bad. I was down to two (#5 & #6 I believe). My mechanic calls to tell me he noticed some metallic sludge in the cylinder upon removing the injector in #5. He tells me he has boroscoped the cylinder, and he is sorry to report that the cylinder wall is "scored", and that the only fix is to replace the motor (~118,000 mi). The car doesn't smoke or use oil. And the car runs smooth as silk at lower RPMs. Yet when I accelerate hard, I get severe missing - just like when the other injectors went bad. Has anyone else heard of this problem? I have had the HPFP replaced. I get codes when this happens, but they all involve the VANOS and the charge air gate....no cylinder misfires are recorded. I am confused, and refuse to take my car into a dealer without some knowledge about what's going on. You'd think if a cylinder was compromised, you get rough operation all the time. And if the cylinder wall was damaged enough to lose compression, it would smoke like a crop duster. I got none of that. Any advice would be greatly appreciated.

[Ingeniator]

Run a compression/leakdown test. If it is off by more than 15-20% I would consider a rebuild/swap.

[Aerotest]

+2 and get another mechanic. Any guy who would diagnose a bad cylinder without a leakdown is incompetent. IMO no oil control problems, no low compression, no replace engine.

[135Pats]

If you have compression and aren't blowing thru a quart a week (and you would be if you smoked a ring or something along those lines), I don't see a need to replace the motor.

[jwzimm]

Also, when you replace the injectors are you getting the car reprogrammed to match the new injector flow values? It sounds like you are getting this done at an independent shop (who may not know). That could be the cause of some of your issues. The DME (engine computer) needs to know the calibration data of each injector to ensure it commands the correct amount of fuel for each cylinder. This data is marked on each new injector and needs to be programmed in to the DME following install.

[mrb3is]

In my mechanic's defense (and he has never given me any reason not to trust him), he told me in a subsequent conversation that he ran a compression test, and the cylinder in question was "significantly lower" than normal. He didn't sound real convincing....and why wouldn't he have mentioned that right away. That is the definitive proof you've got big problems. Just seems fishy.
Plus, I don't want to buy a friggin' motor! $7,500!!!!

[Ingeniator]

Interesting. I would get a second shop to run one. I would also prefer a leakdown test over standard compression. This will let you confirm it is indeed bottom end. Sorry for your bad luck but I'm sure you can find a good used motor for less than $7500

[pwr hungry]

This potentially blows...best of luck for an inexpensive fix OP!

[Tiago@VRSF]

Originally Posted by Ingeniator

Interesting. I would get a second shop to run one. I would also prefer a leakdown test over standard compression. This will let you confirm it is indeed bottom end. Sorry for your bad luck but I'm sure you can find a good used motor for less than $7500

Great advice. A second opinion never hurts, especially when considering the cost of a really expensive repair.

[mankytron]

Yes def get a 2nd opinion. Your missing could be due to the low compression in that cylinder, but get a comp and leakdown test done and get some hard numbers for those tests. These engines have iron liners so if you had mild scoring, a hone and re ring for that cylinder may be all thats needed to bring it up to spec.

[mike@x-ph.com]

+1 on second opinion before shelling lots of money

[ArndtCraft]

Im no mechanic, and this may sound far fetched, but couldn't a misfire be directly related to heavy carbon build up on and around the valve and seat? This would explain both a loss of compression and misfire.

[Ingeniator]

Originally Posted by ArndtCraft

Im no mechanic, and this may sound far fetched, but couldn't a misfire be directly related to heavy carbon build up on and around the valve and seat? This would explain both a loss of compression and misfire.

A leak down will identify if it is rings/bottom end, intake valves, exhaust valves or head gasket.

[mrb3is]

I am currently taking the good advice given here, and getting a second opinion. First blush, the "scored" cylinder was supposed to be #5. New tech could not get #5 to misfire. Misfires all occurred in #2. May be a lifter problem, injector problem, or carbon buildup problem. Doing a compression test today. I have my fingers crossed... My suspicion is a lifter problem. Now... Can lifters be adjusted, or must they be replaced? And, if it's a lifter, and it must be replaced, do they all need to be replaced?

[Ingeniator]

Originally Posted by mrb3is

I am currently taking the good advice given here, and getting a second opinion. First blush, the "scored" cylinder was supposed to be #5. New tech could not get #5 to misfire. Misfires all occurred in #2. May be a lifter problem, injector problem, or carbon buildup problem. Doing a compression test today. I have my fingers crossed... My suspicion is a lifter problem. Now... Can lifters be adjusted, or must they be replaced? And, if it's a lifter, and it must be replaced, do they all need to be replaced?

Could be as simple as VANOS issues. I hope you have better service at this place. Also if the compression is off ask them what the leakdown was for all cylinders and how far off the bad one is. They should also be able to tell you it is leaking from the "X". My bet is carbon buildup if you have any milage. It could be an injector but that is pretty simple to troubleshoot.

[blackshan]

Good luck OP!

[mrb3is]

the problem turned out to be a fuel line that was torqued too tight. Fuel flow choking off at the higher demands. I had the fuel lines torqued properly and had a carbon blast. The car runs better than ever! I will always get a second opinion from now on. And, I will trust my own gut feel too. Thanks for all the support and good advice.

[Hidden]

Originally Posted by mrb3is

the problem turned out to be a fuel line that was torqued too tight. Fuel flow choking off at the higher demands. I had the fuel lines torqued properly and had a carbon blast. The car runs better than ever! I will always get a second opinion from now on. And, I will trust my own gut feel too. Thanks for all the support and good advice.

Awesome news. Great lesson.

[joeyt]

Report back to the original mechanic and tell him he's a con man and that theres a thread staring so.

Please name and shame this guy as he needs to be known by anyone reading this thread he is a con man and was trying to get you to spend 8k when it was just a pipe. So he lied about scoring of a bore and lied about a compression test aswell and also could fix the problem. So thus he is not a good garage at all and needs to close his doors.

Name and shame man

[MDORPHN]

Originally Posted by Ingeniator

Run a compression/leakdown test. If it is off by more than 15-20% I would consider a rebuild/swap.

Agree.

And, btw, a scored cylinder would not be related to the misfires.

Neil

P.S. You might also consider doing a Blackstone (or similar) oil analysis. Together with the compression/leakdown test, it will tell you a lot about the health of your motor.

[Bimmertech113]

Originally Posted by mrb3is

the problem turned out to be a fuel line that was torqued too tight. Fuel flow choking off at the higher demands. I had the fuel lines torqued properly and had a carbon blast. The car runs better than ever! I will always get a second opinion from now on. And, I will trust my own gut feel too. Thanks for all the support and good advice.

Good news. I'm a BMW master tech. If you don't mind traveling to Nashville I would be more than happy to looking at your car for you. I'm significantly cheaper than any dealer or independent. And I know what I'm doing.