[N8N]

Car is '09 335i E92 6MT, purchased with 72Kish miles, now about 74,500. Car essentially looks like a new car inside and out and runs and drives great with one exception.

So I've been having a heavy throttle (not necessarily full, but "brisk" acceleration) surge that's been driving me nuts, and also when I replaced my spark plugs recently I found #6 black and wet. So I ran a couple tanks full of Techron through the car, not thinking that it would really help, but hopeful... then today since it was a balmy 38 degrees outside I re-pulled the #6 spark plug and found it not as black and not as wet, but still not looking like a good spark plug should. I also pulled #2 for comparison and there was a little black around the edges but the porcelain was still white and it looked about like a good plug should. So I strongly suspect that I have a leaky #6 injector and that pouring stuff in the tank ain't gonna fix it.

FWIW I have no codes.

Called dealership, got a quote for $4-500 to replace the injector, and "about $800" for walnut blasting...!

Wasn't real happy about that. Called my buddy that has a franchise shop and he's supposed to get back to me and let me know if he can code in a new injector (I know he can't walnut blast.) Also left a message for IMA Motorsport in Chantilly and am waiting to hear back from them. I stopped by Mach V yesterday and Dan is the guy that could tell me what they can and can't do, will have to get with him when he gets back from vacation. (can't blame the guy for taking some time off though.)

Then I figured it would probably be prudent to flash back to stock - I've been running Cobb's Stage 1 Aggressive Linear map. So I did. Started the car and there was tons of white smoke pouring out of the tailpipe, and the cooling fan came on full high. Shut down, checked codes, I have no CEL but it was showing code P2EE6 Coolant temp sensor plausibility. Reset code, restarted, *seems* fine but I have not driven it yet. Since I had my battery charger out (I always use a charger or power supply when flashing just because) it's charging now because I figure topping up the battery is always a good idea as much of a juice pig as these cars are. I guess I will try an ECM reset, dump another bottle of Techron in and go from there.

Does this sound to you guys like I probably need both the injector and a walnut blast, as I expect? How can I non-invasively confirm the need for walnut blasting? Any other shops I should call in the NoVA/Dulles area?

thanks!

[themyst]

The injector is a DIY and runs $150 or so IIRC. Make sure you get the coupling element and find a local coder to help you code it into the DME (or do it yourself in INPA).

IMO if you have a leaky injector your car would stutter and idle poorly on a cold start and throw misfire codes. I am thinking valve cover gasket (this may be a $400 dollar job on labor alone).

-edit white smoke pouring out of the tailpipe in this cold weather isn't necessarily anything to worry about. Likely just condensation build-up in your mufflers. If your fan goes full blast and you get a red check engine light, then your water pump took a dump. That's not a cheap fix ($800-900 including labor).

[N8N]

The first time I pulled the plugs the "wet" on #6 was clearly gasoline - smelled like gasoline and evaporated in 10 min. or so leaving the plug dry and black.

I honestly can't believe I haven't seen a misfire code, because it sure feels like a misfire. Idle is pretty good but every now and then I think I can detect a little anomaly in it.

Previously I was getting a "mixture control" code but it hasn't come back since I cleared it the first time...? (still no light, just a shadow code.)

I took a closer look this time when I had the plastic cover off because I too was thinking "well maybe I'm getting a VC leak" but I didn't see any oil sitting in the bottom of the plug tube or anywhere else for that matter. Coming from working on Studebakers and my other current vehicle being a Jeep, it's kind of odd not seeing any oil on the outside of the engine at all.

[themyst]

Originally Posted by N8N

The first time I pulled the plugs the "wet" on #6 was clearly gasoline - smelled like gasoline and evaporated in 10 min. or so leaving the plug dry and black.

I honestly can't believe I haven't seen a misfire code, because it sure feels like a misfire. Idle is pretty good but every now and then I think I can detect a little anomaly in it.

Previously I was getting a "mixture control" code but it hasn't come back since I cleared it the first time...? (still no light, just a shadow code.)

I took a closer look this time when I had the plastic cover off because I too was thinking "well maybe I'm getting a VC leak" but I didn't see any oil sitting in the bottom of the plug tube or anywhere else for that matter. Coming from working on Studebakers and my other current vehicle being a Jeep, it's kind of odd not seeing any oil on the outside of the engine at all.

The N54 misfire detection is ultra-sensitive. If you actually misfired it would throw an SES light and your car would shut fuel and spark off on that cylinder until you restart the car.

A slight hiccup in idle may very well require a valve cleaning, but I don't necessarily buy that it's a necessity. It's gross to look at in pictures but it's not necessarily the solution.

If you take a picture of the actual "bad" plug, we could give you more feedback. If you see oil on the threads, that's a VC leak. If you see wet oil on the plug itself, also VC leak. If it's just wet fuel, could be an injector. Best to pull the plug to check before you cold start the car in the morning.

See below picture of my #6 plug at 32k miles. That required a VCG job.

[N8N]

Well, I am pretty much a dumbass, just ask my friends, but sometimes I do smart stuff. The car is all back together but I did snap a pic of #6 before I put it back in. What say you?

[techwhiz]

Looks to be running rich on that plug. Leaky injector.

[Jeff@TopGearSolutions]

Originally Posted by techwhiz

Looks to be running rich on that plug. Leaky injector.

Very likely or Valve cover gasket. I'm leaning towards injector only cause the Valve Cover gasket usually makes a bigger mess and it looks more oily then it does just flat black, generally speaking.

[solishe]

My car was running very rough at idle and seemed like misfire was occurring but no codes. Took it to indy shop and they could see cylinder 5 was running rough even though no codes. They swapped coils, no luck. Took to dealership, of course no codes no work. Finally got a code, sure enough it was a cylinder 5 misfire. Got injector replaced by dealer under warranty, all is well now. You can get a new injector and decoupler for $136 shipped at thebmwpartstore.com if out of warranty.

[N8N]

Well it is running great (but slow) on stock tune. Wondering if my local Shell's 93 isn't so 93. Still waiting for my buddy to call me back about coding the injector. So far dealer is only place that seemed confident Now I'm wondering if the surge was knock related timing pulls.

[olston84]

Dealership replaced five of the six injectors on my car under warranty at about 42K miles. I also have an 09'. So there's definitely something with some of the injectors that makes them go bad. So I'd probably start with the injector(s).

[BMWM.D.]

If you suspect an injector issue (and it looks that way from your pic), I'd act sooner than later. I've dealt with quite a few cars lately that have come in almost hydro-locked from fuel due to a leaking injector. Most of them have been later cars -- 2009-2011.

The last 2 I fixed actually had raw fuel dripping out of the turbo/downpipe area. Pretty scary to think about what this can do to your cats (if you have cats) or other engine parts.

[Spoolin1]

Could it be possible that the Cobb AP tune has cylinder 6 running a bit richer due to it being a hotter cylinder? I know in my S2000, we have a bit more e85 going to cylinder 4 because it's the one that gets the hottest. Even though full boost AF in the S is targeted around 11.8 on my WB o2 for all 4 cylinders, cylinder 4 is still getting a bit more fuel than the other 3 due to the way my tuner set it up.

[Ænema]

Originally Posted by N8N

Well it is running great (but slow) on stock tune. Wondering if my local Shell's 93 isn't so 93. Still waiting for my buddy to call me back about coding the injector. So far dealer is only place that seemed confident Now I'm wondering if the surge was knock related timing pulls.

Grab some datalogs to check on the timing. Also, a slight blip/variation at idle is pretty normal.