# Rough Idle bummerfest



## Kittennmittenz (Jan 23, 2017)

Hello all, 
Just bought a lightly used (114K miles) 2011 335d for only 12K :thumbup:
I'm not new to diesels but definitely new to BMW. The car is in damn good condition considering the amount of miles on the vehicle. just needs some trim pieces and the side indicators replaced due to age

HOWEVER, while driving from Phoenix to California, I did get a check engine light and reduced power (2k rpm limit) that seemed to clear itself after 2 minutes. Power seemed normal afterwards until i got onto surface roads. The car has developed a rough idle that almost feels like a misfire when the vehicle is idling at a stop. the SES light is now on full time and is reading generic code P0101 which I have read on here could be anything from the MAF to DDE (is this what the ECU is called?) or an injector. I took it into a shop and the claimed they could not replicate the rough idle but did do 12 - 13 factory programming updates. Problem went away for 1 week then has returned. 

I know the guy I bought it from and drove it for a whole week before purchasing, the problem didn't exist about a month ago. Trans/diff service was done roughly 2000 miles ago, no problems to report in the 1500 miles between the service and me purchasing it. It also has never had a CBU clean out done (HOW TF???) 

Has anyone had that code in combination with the very rough idle? What are the chances this isn't an injector??? And if it is tuning, should I wait till next month when I do the full delete exhaust, egr race pipe, and 2.8 tuning from fixmyVW??

I am still happy with the car, nicest car I've owned for sure. Cannot wait to unleash all the torque in this monster!!!!

oh and as far as suspension upgrades, just swap to M3 parts or what?


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## ingenieur (Dec 26, 2006)

Kittennmittenz said:


> Has anyone had that code in combination with the very rough idle? What are the chances this isn't an injector??? And if it is tuning, should I wait till next month when I do the full delete exhaust, egr race pipe, and 2.8 tuning from fixmyVW??


So why are you here?


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## Kittennmittenz (Jan 23, 2017)

ingenieur said:


> So why are you here?


Has anyone had that code in combination with the very rough idle? What are the chances this is an injector???

^^^ that's a question. People come to forums to ask questions and get answers. So it seems that even the diesel bimmer guys are funny guys too :rofl::rofl:


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## Ozer (Sep 17, 2015)

Clean your MAF, check for vacuum leaks, see if any of the boost hoses popped out. All easy and free things you can do. 
Im not familiar with that code, if you are deleting all that stuff then it may get fixed with tuning and such. Good luck and post updates after its all done.


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## FredoinSF (Nov 29, 2009)

Can't help with the code, just here to say welcome and congrats on the new to you BMW Diesel.

Wondering how you're planning on getting away with the mods in CA, assuming you're going to "reset it" come smog time?


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## imtjm (Oct 5, 2004)

so, you brought it into a shop and they didn't pull the BMW DTC's? The SES was on, so there had to be something other than a generic P code. The shop did a bunch of programming updates, but didn't do any troubleshooting specific to the MAF Sensor or issues commonly associated with P0101? Things like check the MAF sensor to see if it's dirty, testing the MAF sensor, checking air filter, cracked intake boot/vacuum leaks, bad EGR throttle valve (btw, BMW extended the EGR throttle valve warranty for M57 diesel engine to 10yr/120k miles, you can verify if your car has it by going to bmw-rp.com)?


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## Nadir Point (Dec 6, 2013)

CBU cleaning is never a bad idea - especially at that mileage. I'd be willing to bet that, along with the typically associated carboned-up injector tips will be your findings.


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## BB_cuda (Nov 8, 2011)

I had P0101 and I unplugged the MAF and replugged it. My connector doesn't give the nice click sound so I guess it has a little play now. I had just done an oil catch can install and had the MAF connector off while the intake box was puled out of the way. After replug and driving for about 10 minutes the SES went away. This was at about 38,000 miles and I'm now at 53,000 miles.

The only real way to know if you have CBU is to look. The intake manifold has to be pulled off and use a boroscope to look into the head's ports. Also, use the scope to look inside the intake. I only had a minor buildup on my ports. The main rectangular ports were very clean and the tangential ports (smaller round ones) had a little bit but not enough to warrant walnut shell blasting. I have stopped the carbon source and "most of" the oil source which both mix to form the pudding like CBU that collects. I say most of the oil source as the turbos themselves can theoretically have an oil seal leak and the head itself can have a valve stem leak. Both of these can happen on a gas car too though. I feel that early on the main source of oil comes from the crank case ventilation scheme. My oil catch can doesn't seem to get that much collection though. So, either the oil isn't condensing in it (like it should) or I don't have much oil vapor coming out of the crank case ventilation duct. Last time I looked in my EGR valve, it was bone clean and no oil film. It may be time for another peek though. The winter months are when it should be cooler to get better collection within the can. My dipstick in the can barely registers that I have anything in it which means about 0.3" full or so. Dipstick doesn't go quite to the bottom. Come over to e90post/m57 and n57 diesel section where we do a fair amount of mods.

I did brisk past one other proven method of stopping and possibly reversing CBU. A number of people have went to meth/water injection which cleans the intake and head's ports. A user here and E90post named Hoooper showed us before and after pictures of running meth with about 10,000 or 15,000 miles in between. The ports cleaned up. I have no went to meth injection myself but there are a group of believers out there. Of course, meth inj gives another 20 hp or so too :-]. Hoooper will likely be along shortly to attest the cleaning that it does.


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## Kittennmittenz (Jan 23, 2017)

Update: rough idle is now a constant issue. My plan is to do all of the modifications noted above, plus the CBU clean out. (Along with other boring maintenance stuff) I can't imagine the problem existing after that. Will check the MAF, vacuum lines, etc. while we are in there. Will update once done. 
Hopefully, problem solved and we can skip to just exhaust videos and performance fun!!
Just ordered the full delete exhaust and egr race pipe, 2.8 tuning, larger intercooler, and plugs for those swirl flaps. I spoke with the guys from FixmyVW and he mentioned that JR tuning is working on 500hp tune/turbo kit for these cars!!

Do these engines have the crankcase oil fumes routed into the intake like diesel pickup engines do?

Also, can someone point me in the right direction for the water/meth injection kits?? I've ran them on diesels before and have had great results


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## Nadir Point (Dec 6, 2013)

Kittennmittenz said:


> Do these engines have the crankcase oil fumes routed into the intake like diesel pickup engines do?


Yep - and it is the precursor to CBU. I presently have my vent branched through a catch can on the intake side with the other side of the tee dumping to the old DEF port at the bottom of the downpipe.


Kittennmittenz said:


> Also, can someone point me in the right direction for the water/meth injection kits?? I've ran them on diesels before and have had great results


W/M is certainly a great add-on for the diesels. I have 3 running it right now. I'd recommend buying a pump, tank, nozzles, solenoids, switches, etc. and roll your own. It costs less, works better and is more reliable in the long run, at least in my experience.


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## Michael47 (May 9, 2014)

Kittennmittenz said:


> Do these engines have the crankcase oil fumes routed into the intake like diesel pickup engines do?


I think you are going to find that pretty much any vehicle with an internal combustion engine has crankcase fumes routed to the intake manifold. (I stand ready to be educated about that, but since the 1967 addition of this feature was credited with taking care of about 80% of pollution from such engines, I doubt it would be ended easily.)

But yes, BMW's diesels have those fumes routed to the intake. And yes, the combination of oil vapors and soot can result if the formation of concrete-like carbon deposits.


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## Kittennmittenz (Jan 23, 2017)

Sorry all for the lack of updates, finally got the CBU clean up done and that was "fun" to say the least.

After 116k miles with no CBU clean out the intake ports on the manifold were reduced to as little as 50% of the original diameter. The manifold had to be soaked over night and pressure washed to remove all of the build up. Trying to load pictures, it was pretty shocking to see how bad it was. The swirl flaps were so gunked up with carbon that they could barely operate. This stuff is sticky and tough to get off!
Service cost jumped to $1400 which oddly enough, the local dealership had the OE intake manifolds in stock for the same price. 

I only drove it for a day before it went to another shop for the performance parts but I can't wait to get the car back after all the modifications

I'm still kind of torn on the overall "value" of these cars but besides this issue the car has never had a single issue, (besides how pricey a damn headlight bulb is) I'm not sure how many guys have kept there 335Ds past 100k miles, seems like everyone got scared off around 90 ish. Well we will see how it goes I guess, I drive 30k miles a year so I'm sure I'll find out soon enough


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## imtjm (Oct 5, 2004)

"value" is a subjective personal judgement.

people probably got scared off using the same judgement as any other car. Doing $3k-$5k worth of repairs to enable your car to run another 100k, or spend $50k on a new car to run 50k under warranty. People aren't always the best at math or cost benefit analysis.


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## Hoooper (Jun 17, 2013)

ingenieur said:


> So why are you here?


I dont even understand this question?


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## imtjm (Oct 5, 2004)

Hoooper said:


> I dont even understand this question?


probably because you didn't read OP's original post, "And if it is tuning, should I wait till next month when I do the full delete exhaust, egr race pipe, and 2.8 tuning from fixmyVW??"


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## Hoooper (Jun 17, 2013)

imtjm said:


> probably because you didn't read OP's original post, "And if it is tuning, should I wait till next month when I do the full delete exhaust, egr race pipe, and 2.8 tuning from fixmyVW??"


Of course I read the OP. The response doesnt make sense. In what way should your future deletes prevent you from being here?


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## imtjm (Oct 5, 2004)

Hoooper said:


> Of course I read the OP. The response doesnt make sense. In what way should your future deletes prevent you from being here?


I won't put words in @ingenieur mouth, but I understood the rhetorical question. OP is doing a bunch of stuff which relates to the issue, so why bother asking the question now when it simply doesn't matter.


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## Kittennmittenz (Jan 23, 2017)

Well finally got the car back after an annoying issue with the exhaust kit...STAGE 2.8 is AWESOME!! haven't done any hard pulls 0-60 but man the passing power is insane. Getting on the freeway at about 35-40 behind someone who couldn't find the gas pedal lol, rolled into it to pass and by the time I looked down the speedo read 120

The exhaust note while cruising around parking lots sounds angry as hell, it's intoxicating 

Will log MPG over the next few weeks and will try and get an accurate 0-60 time


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## Kittennmittenz (Jan 23, 2017)

Oh and to cover the rough idling issue

Rough idle, delayed acceleration, poor MPG, and SES light all were remedied with the extensive CBU clean out and all the other various filter/fluid/oil servicing


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## imtjm (Oct 5, 2004)

well there you go then...all problems solved, except the inevitable speeding tickets :rofl::rofl:


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