[asus389]

My car was in today at the dealer with a list of things to check because the CPO warranty is up in a month. I mentioned that the car was sometimes idling rough and knocking/ticking soon after start - despite the cylinder head being replaced a year ago. Its no where near as bad as it was, but it still does it on occasion - especially when the temp swings from cold to warm (ie - first hot day after winter). The revs also sometimes bounce around at idle for the first couple minutes. It appears like the computer is preventing a stall or something. When the engine warms up after being driven for a bit things smooth out.

The SA called me back and said they didn't come up with anything to explain this, but suggested that I might try the dealer "fuel injector cleaning service" for $199. Its not part of the CBS schedule, but he said they sometimes recommend it for higher mileage cars. Mine has 70k.

Does anyone know what this is? Is it any different than just running a couple of bottles of techron through the car? If so, how so? Is this likely to solve my issue?

I did find: Fuel System Cleaning SIB 13 01 07.pdf

And also this, which (I think) describes the procedure further down in the document:

B130107Procedure_A,B,C,D

thanks

[J02 335i]

Its a dealer money grab in my opinion, I have yet to see a plugged or partially plugged fuel injector in my 10+ years of being a licensed tech.

More then likely you have a bad injector that leaks slightly when the car is off and causes the rough idle on a cold start, or an ignition coil on its way out.

[jphughan]

Originally Posted by J02 335i

Its a dealer money grab in my opinion, I have yet to see a plugged or partially plugged fuel injector in my 10+ years of being a licensed tech.

More then likely you have a bad injector that leaks slightly when the car is off and causes the rough idle on a cold start, or an ignition coil on its way out.

Pretty much this. My wife got suckered into doing this on her Mini Cooper S when it was in for recall service, even though it only had 36K miles. Unfortunately she didn't call me before telling them to go ahead, otherwise I would have checked into it, and used an indy mechanic we love and trust if it sounded like something that was actually necessary. Anyway, the general wisdom is that gas is clean enough these days that injector cleaning isn't a maintenance item; it should only be done if have symptoms that indicate they might be dirty. Sounds like the dealership at least has some symptoms to justify their recommendation, but I'd check what the previous poster mentioned first.

[Bavarian Tech]

You mention rough idle, the famous n52 cold engine shake, or more severe ?
What gas are you running ?
Oil type and how frequent ? Vanos solenoids can get clogged making the situation worse

Don't buy into their fuel injector service, especially at that price..Go to your local parts store, advanced,autozone, whatever and get a can of "Seafoam" throw it in your gas tank, call it a day..

Ticking and knocking are different sounds, knocking is a big big big no no..N52 can develop a slight ticking, you already had your head replaced once which is the fix according to BMW, how often is the car driven ?

[asus389]

Originally Posted by msbc721

You mention rough idle, the famous n52 cold engine shake, or more severe ?
What gas are you running ?
Oil type and how frequent ? Vanos solenoids can get clogged making the situation worse

Don't buy into their fuel injector service, especially at that price..Go to your local parts store, advanced,autozone, whatever and get a can of "Seafoam" throw it in your gas tank, call it a day..

Ticking and knocking are different sounds, knocking is a big big big no no..N52 can develop a slight ticking, you already had your head replaced once which is the fix according to BMW, how often is the car driven ?

I run shell 93 most of the time. The sound is similar to the ticking was, but more muted. Oil was changed according to the CBS I'm guessing until I bought the car as a CPO with 37k on it, since then I have changed it every ~7500. It has 70k miles on it now. I just changed the oil like 2k ago and prior to that I run a bottle of techron through it with a full tank. I do this about once a year. What is the "the famous n52 cold engine shake"? Is that a normal thing?

[Bavarian Tech]

Everyone will have their different opinion about it, normal as its not going to cause any problems short or long term, but its not right if that makes sense..You can either clean them which I have done, which made no difference or replace em..which is about $100 per cam...so $200 for a complete job..Your under CPO so you might be able to bitch about it enough and get ones but 9 chances out of 10 they'll just "clean" em. Take a video with your phone on a bone cold start so you have proof to back up your claim.

[Bavarian Tech]

Found a TSB

For N52 BMW will not replace the vanos solenoid, instead clean and reprogram DME so odds of getting them under warranty doesn't look promising

[asus389]

Originally Posted by msbc721

Found a TSB

For N52 BMW will not replace the vanos solenoid, instead clean and reprogram DME so odds of getting them under warranty doesn't look promising

Hmmm... I seem to recall the VANOS solenoid was replaced last year when SES came on. Printout says "vanos solenoid valve (inlet) jammed hooked up isid and found fault for inlet vanos solenoid valve soiled or faulty. follwed test plan nec. to replace vanos solenoid valves inlet and exhaust.

I do recall it running better following this repair, but the roughness seemed to come back this spring. Meh...

thanks for all the suggestions BTW.

[Bavarian Tech]

Only suggest i can recommend is pulling em,clean with some brake cleaner, compressed air em dry. Swap em around

[Jace_91]

I always get offered this as well, and I have 30k miles, I feel like it must be a money grab because if it was the important wouldnt you think it was covered by the maintainence plan?

[asus389]

Some follow up... The battery finally went out, showing some low voltage errors and requiring jumps a couple times in the last month. Upon replacing it much of the rough idle after cold start is gone. Its like 95% better. Can anyone explain this?

[roadkillrob]

Seems to be common, rough running when the battery is going bad, somehow the low voltage affects the ignition/electronics or fuel pumps/injectors enough to cause this. When the car is idling, the electronics will be getting battery voltage and if this is low, like 11 volts, it could cause something like the pulse rate of the injectors to be slow or the ignition to be a bit off. Once you get on the gas a bit, the alternator will make enough power to get voltage up over 13 where it belongs. Just a thought!

[GoRomeo]

Originally Posted by Bavarian Tech

You mention rough idle, the famous n52 cold engine shake, or more severe ?
What gas are you running ?
Oil type and how frequent ? Vanos solenoids can get clogged making the situation worse

Don't buy into their fuel injector service, especially at that price..Go to your local parts store, advanced,autozone, whatever and get a can of "Seafoam" throw it in your gas tank, call it a day..

Ticking and knocking are different sounds, knocking is a big big big no no..N52 can develop a slight ticking, you already had your head replaced once which is the fix according to BMW, how often is the car driven ?

Mr Bavarian Tech...

I experienced a rough idle on cold start this morning on my N52 engine 330i. First time. No codes or anything just yet. I changed my plugs last March and also swapped and cleaned my vanos solenoids. I use 89 gas most of the time.

I m thinking of getting a Techron fuel injector cleaner but whats this
"Seafoam" you are talking about?

Anyone else experienced this rough idle on their N52? Also some shaking and I even heard like a pop from the muffler. It only lasted like 10 secs then everthing was normal....weird.

[Meeni]

I had success in the past with Techtron cleaner. But as said above, dirty injectors are not the only source for rough idling, so it may work for you or do nothing (if the real issue is another one). Worth a try, a bottle of injector cleaner is 10 bucks and 2 seconds of your time.

[GoRomeo]

Originally Posted by Meeni

I had success in the past with Techtron cleaner. But as said above, dirty injectors are not the only source for rough idling, so it may work for you or do nothing (if the real issue is another one). Worth a try, a bottle of injector cleaner is 10 bucks and 2 seconds of your time.

hi there thanks! Yeah thats I am gonna do. I will try the Chevron injector claener, or Lucas (I ve heard good thing about it), I will do oil change. I hope is only a bad gas??

If all this does not help, I will have to replace coils. Still running on original coils. I am at 110k miles. No CEL lights though...

[Meeni]

Be sure to use the Techron cleaner, the other chevron thing that does not have the Techron label is not as effective apparently. Don't know if Lucas is good or not. Beware that many of these products are snake oil and very few do something useful.

[GoRomeo]

Originally Posted by Meeni

Be sure to use the Techron cleaner, the other chevron thing that does not have the Techron label is not as effective apparently. Don't know if Lucas is good or not. Beware that many of these products are snake oil and very few do something useful.

thanks!

I ve seen 2 Techron bottles, one is Fuel System Cleaner and the other is Fuel Injector cleaner?? I ve used the fuel system cleaner a few months ago. I guess Ill try the Fuel injector cleaner this time.

UPDATE:
I went to the parking lot and start my car see if rough idle was still there like this morning, but no all was good and normal. I guess the ultimate test would be starting again in tomorrow morning. I will buy the techron injector cleaner tonight.

[M3th_add1ct]

Originally Posted by J02 335i

Its a dealer money grab in my opinion, I have yet to see a plugged or partially plugged fuel injector in my 10+ years of being a licensed tech.

More then likely you have a bad injector that leaks slightly when the car is off and causes the rough idle on a cold start, or an ignition coil on its way out.

hi maybe you can give me input on this similar problem. I just swapped all 6 coils and plugs today 56 degree cold day I go to start the car I hear knocking around my dash driver seat engine wants to stall rpm jump up n down check engine light came on suddenly i hear fans come on really loud and I shut off car as I exit car I see more than usual white smoke and smell of pure gasoline. does this sound like a leaky injector?? I will diagnose obdII later on after work

[M3th_add1ct]

Originally Posted by GoRomeo

thanks!

I ve seen 2 Techron bottles, one is Fuel System Cleaner and the other is Fuel Injector cleaner?? I ve used the fuel system cleaner a few months ago. I guess Ill try the Fuel injector cleaner this time.

UPDATE:
I went to the parking lot and start my car see if rough idle was still there like this morning, but no all was good and normal. I guess the ultimate test would be starting again in tomorrow morning. I will buy the techron injector cleaner tonight.

I had the same thing happening to me starts up fine no codes no nothing other days it wants to act up . is like there is no problem one day next day is all codes and SES light and check engine lmao are cars are moody or have their period lol I have an e92 2007

[GoRomeo]

Originally Posted by nemesis_M3

I had the same thing happening to me starts up fine no codes no nothing other days it wants to act up . is like there is no problem one day next day is all codes and SES light and check engine lmao are cars are moody or have their period lol I have an e92 2007

LOL I agree. I never had SES lights or anything.... im planning to replace my coils soon. I wonder how can we test the coils? Anyone?

UPDATE:

Mine has done it only once. That same day I bought a bottle of Techron Injector cleaner with about half of tank of gas and no problem ever since. Mornings start just fine. Lets see maybe it was bad gas or something.

I ll keep you all posted.

[M3th_add1ct]

Originally Posted by GoRomeo

LOL I agree. I never had SES lights or anything.... im planning to replace my coils soon. I wonder how can we test the coils? Anyone?

UPDATE:

Mine has done it only once. That same day I bought a bottle of Techron Injector cleaner with about half of tank of gas and no problem ever since. Mornings start just fine. Lets see maybe it was bad gas or something.

I ll keep you all posted.

i got 4 spare coils i swapped yesterday 2 were bad i replaced all 6 if you want ill ship em to you so you can diagnose just ship it back when you are done

[GoRomeo]

Originally Posted by nemesis_M3

i got 4 spare coils i swapped yesterday 2 were bad i replaced all 6 if you want ill ship em to you so you can diagnose just ship it back when you are done

Cool man thanks for the offer. So basically what you are saying is to test them individually or replace 4 of them see if idle improves, or is there another way of diagnose? Thanks again!