[Jeff@TopGearSolutions]

With the amount of new threads recently asking about misfires and what to do I thought it was only appropriate to help everyone in a one stop shop.

A lot of us are getting a good amount of miles on our cars and historically when people tune their car for the first time all of the weakest links appear. Before you blame the tune here are few things to check over or replace.

Sparkplugs should be changed about every 25K on tuned vehicles. Coilpacks normally last a little longer but it all depends on your conditions. You also want your HPFP and injectors to be up to date and strong.

UPDATE: Cobb has been generous enough to make a great video for everyone:
http://www.youtube.com/watch?feature...&v=FsNK1ySAlSo


Here is a list of things you can try in no particular order and there may be more. I would suggest starting with the least expensive ideas first.

-Spark plugs
-Coilpacks
-Injectors
-High Pressure/Low Pressure Fuel Pump
-Carbon Build up in intake valves
-Vanos Solenoid

Here are few ways to troubleshoot:

If the misfire is on multiple cylinders:
The cheapest way to fix this is likely replacing all 6 spark plugs. On the off chance it may be coilpacks.

If the misfire is on one or two cylinders:
Try swapping coil packs to see if the problem moves to another cylinder: i.e. if cylinder 1 is misfiring, swap coil 1 to 2 and see if the misfire now happens on cylinder 2. If it moves the coil pack needs replacement.


If changing spark plugs and replacing coil packs does not work it could be the following:

Fuel related, I.e. injectors, HPFP, or LPFP. Normally attributed with cold start misfires, fuel codes and bad idle.

or

Excessive carbon build up in the intake valves

or

Last but not least it may be a vanos solenoid on its way out or needs to be cleaned.

This should help most common misfires but there are some cases where its not as easy to troubleshoot. The above mentioned is the most common causes but your particular problems could be more involved.

Feel free to add to the list if you have had a problem and fixed it. The more details the better. Everyone can use this thread to troubleshoot and ask for help. Please respond and post your misfire problems here.

[import36]

sticky?!

[JamesM3M5]

Yes, STICKY THIS THREAD. It's a little more "politically correct" than the previous thread a couple months back entitled "Change your damn plugs... stop wasting forum space..."

But yeah, this is long overdue. Thanks, Jeff!

[cyniclaus]

Thanks, I changed my plugs at 45k and it seemed to solve my problems. I've got about 8k on AP Stage 1

Is there a recommended mileage to change the coilpacks or a vertain mileage where they typically start to go?

What about carbon cleaning? At what mileage should we get cleaned and can any mechanic do it or should it be a BMW specialist? Can/will the dealer perform that?

Are the coilpacks or carbon covered under the CPO warranty or is that considered normal wear like brakes or the clutch?

[vasillalov]

So basically, what you are saying that after eliminating the obvious: spark plugs and coils, it could be a wide variety of things that can cause a misfire: anything from carbon build up, bad fuel injector, fuel pump , etc etc.

...not the moon phase?

What do you suggest for my situation:

* 25K miles on car
* Brand new spark plugs
* Swapping coils does not move the misfires to a different cylinder
* Injectors and HPFP replaced less than 5K miles during recall campaign

[GeorgiaTech335coupe]

I think injectors should get their own step, after spark plugs and coils. In my case I have had more injectors go out than bad plugs and bad coils combined. Plus they are the 3rd cheapest step before LPFP, HPFP, and carbon buildup cleaning.

[JamesM3M5]

Carbon cleaning should run $800-1000. Not particularly cheap, but not too steep, either. It should be done every 30-40k miles at least. I bought mine with 46k, did the cleaning at 47k, and the buildup was horrendous. I noticed much smoother running and a little better power at the top end. I manually scrubbed with gun cleaning brushes and carb cleaner. Forget that! It was a mess and a PITA. I bought the BMW walnut shell blasting tool to do Mini and BMW DI engines. Maybe I'll run a special on cleaning services next month...

Wow, I didn't know injector prices had come down that far: 13 53 7 585 261 is $135 retail, available from Tischer BMW for $108 (20% off retail) each.

Vas, try replacing the coils - all of them. If they don't fix it, you're not out a whole lot. 12 13 7 594 937 $60 retail, $48 from Tischer.

[GeorgiaTech335coupe]

Originally Posted by JamesM3M5

Carbon cleaning should run $800-1000. Not particularly cheap, but not too steep, either. It should be done every 30-40k miles at least. I bought mine with 46k, did the cleaning at 47k, and the buildup was horrendous. I noticed much smoother running and a little better power at the top end. I manually scrubbed with gun cleaning brushes and carb cleaner. Forget that! It was a mess and a PITA. I bought the BMW walnut shell blasting tool to do Mini and BMW DI engines. Maybe I'll run a special on cleaning services next month...

Wow, I didn't know injector prices had come down that far: 13 53 7 585 261 is $135 retail, available from Tischer BMW for $108 (20% off retail) each.

Vas, try replacing the coils - all of them. If they don't fix it, you're not out a whole lot. 12 13 7 594 937 $60 retail, $48 from Tischer.

Best coil prices are found here. Free shipping if your order is over $50, so order a spare.

http://www.bimmerpartswholesale.com/...921+4294967171

[vasillalov]

Originally Posted by JamesM3M5

Wow, I didn't know injector prices had come down that far: 13 53 7 585 261 is $135 retail, available from Tischer BMW for $108 (20% off retail) each.

Yep. Bought one to replace it on cyl1, hoping that it will cure the problem. I suspect this injector was not calibrated correctly into the ECU, but I will know more once I get my INPA cable.

Originally Posted by JamesM3M5

Vas, try replacing the coils - all of them. If they don't fix it, you're not out a whole lot. 12 13 7 594 937 $60 retail, $48 from Tischer.

6 new coils at just 25K miles?! That's rather illogical. If the injector replacement does not cure it, I will try maybe 1 new coil.

The one thing I hate the most is throwing money on parts and blindly hoping it will fix a problem!

[vasillalov]

What I'd like to know is this:

OEM specifications for electrical resistance of the coils. One could easily do a home test with a mid-range volt meter.

[JamesM3M5]

Originally Posted by vasillalov

What I'd like to know is this:

OEM specifications for electrical resistance of the coils. One could easily do a home test with a mid-range volt meter.

hotrod posted a thread on this a few weeks back. He checked his used coils versus new ones. I don't think they solved his misfire, but he did solve it in that thread.

Resistance doesn't tell us enough about the behaviour of the coil under load. It's useful to check, but probably isn't the end-all of the coil diagnosis.

I agree on not throwing parts at a problem - wastes time and money. But you can easily sell the set to anyone here on the forums. Any track or drag race enthusiast should have a spare set whenever they go to a track event.

[landman2k1]

When I installed my JB4 a few months back I was getting a misfire on cylinder 1, swapped the 1/2 coil and the misfire jumped to cylinder 3. Strange! Just got around to changing plugs and all seems to be well. 40K miles, so it was probably time anyway.

[blisstik]

Don't forget about resetting your adaptations! It should be one of the first things you try out before swapping any parts. This is helpful if you feel that your car is starting to bog in the low RPMs. I know it worked for me.

http://www.e90post.com/forums/showthread.php?t=386376

[vasillalov]

Originally Posted by blisstik

Don't forget about resetting your adaptations! It should be one of the first things you try out before swapping any parts. This is helpful if you feel that your car is starting to bog in the low RPMs. I know it worked for me.

http://www.e90post.com/forums/showthread.php?t=386376

I have an email from Rob from Cobb in which he specifically recommends NOT to reset adaptations because boost will get choppy.

[zeel]

Originally Posted by JamesM3M5

Carbon cleaning should run $800-1000. Not particularly cheap, but not too steep, either. It should be done every 30-40k miles at least. I bought mine with 46k, did the cleaning at 47k, and the buildup was horrendous. I noticed much smoother running and a little better power at the top end. I manually scrubbed with gun cleaning brushes and carb cleaner. Forget that! It was a mess and a PITA. I bought the BMW walnut shell blasting tool to do Mini and BMW DI engines. Maybe I'll run a special on cleaning services next month...

Wow, I didn't know injector prices had come down that far: 13 53 7 585 261 is $135 retail, available from Tischer BMW for $108 (20% off retail) each.

Vas, try replacing the coils - all of them. If they don't fix it, you're not out a whole lot. 12 13 7 594 937 $60 retail, $48 from Tischer.

If you decide to run a special on cleaning services for carbon buildup, please post it in the mid-atlantic forum. I'm definitely looking into this in the next month or so.

[Mike@N54Tuning.com]

When tuned plugs should be replaced every 15-20K. Will solve a lot of headaches and its cheap to do if you can DIY. Just grab a spark plug socket and order some plugs and go for it. Your car will thank you.

Mike

[nitehawk]

Originally Posted by vasillalov

I have an email from Rob from Cobb in which he specifically recommends NOT to reset adaptations because boost will get choppy.

Care to share? Wouldn't that just be a temporary symptom until the DME relearns each adaptation?

[vasillalov]

Originally Posted by nitehawk

Care to share? Wouldn't that just be a temporary symptom until the DME relearns each adaptation?

Sure:

from: Irish rob.irish@cobbtuning.com
to: Vasil Lalov <vasil.lalov@gmail.com>
date: Tue, Dec 20, 2011 at 12:37 PM
subject: Re: Stage 2+FMIC - Misfires
mailed-by: cobbtuning.com
: Important mainly because of your interaction with messages in the conversation.

Hi Vasil,

Please see the attached map to see if we can get your misfires under control. Let me know how it works.

The boost control should smooth out over time. Resetting the learning would delay it.

Cheers,
Rob

I agree. The ECU will eventually re-learn new adaptations.

BTW, that map he gave me only made things worse. I am not saying anything else till I get my new injector in the mail. I am also waiting on an INPA cable so that I can do my own coding, Local stealership wants $160 for recoding. Local indy shop wants $90 for recoding a single injector. Pffft!

[Jeff@TopGearSolutions]

I updated first post with a little more info.

If you guys think I should add something specific just shoot me a PM with "misfire code thread" in subject line.

[SlowerThanU]

For heavy meth users (that sounds bad), O2 sensors should be on the list
For high HP cars, compression/leak own should be checked

[chesney72]

Not sure if this is a fix but I think it helps. If you take the coils out and clean the contact point of the residue that can build up on them it will give the coil a better chance to get a clean contact with the spark plug.

I've been missfire free since doing this....touch wood!!

[mundo74]

Originally Posted by vasillalov

Sure:



I agree. The ECU will eventually re-learn new adaptations.

BTW, that map he gave me only made things worse. I am not saying anything else till I get my new injector in the mail. I am also waiting on an INPA cable so that I can do my own coding, Local stealership wants $160 for recoding. Local indy shop wants $90 for recoding a single injector. Pffft!

Tell us a bit more about this inpa cable. Was hoping bav technic added this to their cable