[firedragon]

Hello All,

I am new to BMW's and need some help and assistance with a bad misfire issue that has come out of nowhere.

Some history: I had a service from an independent garage that I know well last weekend [Saturday] and they changed all 6 spark plugs as well as oil and filters etc. All was well.

On Wednesday I ran the petrol tank down to --- on the clock [not intentional to get that low just caught out on the motorway], probably took it down to -3 miles. Anyway, filled up the tank at a Morrisons and went on my way. 5 minutes back down the motorway and the car started to hesitate on acceleration and then it misfired and then ran on 5 cylinders with the EM light on.

Took it straight to the garage that done the service as thought it was a plug issue. They done a diagnostic and it stated a misfire in cylinder 5. They proceeded to swap the plug for another, reset the codes and ran the car, the EM light come on again. This time it stated cylinder 2 was misfiring. They then swopped over the coil from cylinder 2 with 1 and swopped the plug from 6 etc to eliminate any plug or coil issue. Reset again, ran the car and the EM light came on again - still referencing cylinder misfire.

They assured they torqued the bolts to the correct setting so no combustion gas is leaking out and that the coils have been seated properly - this I have double checked.

I cannot understand why the misfire went from cylinder 5 to cylinder 1 when all the plugs and coils are ok? Furthermore, one may think the culprit could be a clogged injector from some dodgy fuel but again would this not be consistent to one cylinder or several/all - why effect one then another with the original cylinder effected now ok..?

I have had a very low battery warning since buying the car some eight months ago and have just replaced the battery for new yesterday. This was replaced after the misfire issues.

After reading many posts it would seem that most people have a consistent cylinder down whereas I have had one and then it moved to another and is now consistent to that cylinder - electrical issue maybe, however all wiring to the coils seem ok.

Some people say that the low battery voltage can mess around with the electrical system and this could have spiked the ECU/DME and hence causing the strange misfire.

Others say that when the plugs are changed the ECU needs to be reprogrammed i.e to reset the adaption module - I thought though that this adaption module reprograms itself to ensure the right spark across the plugs etc.

Basically, now I am getting nowhere with the garage that done the service of which I think they are probably not at fault anyway, and the stealership are quoting £216 to just have a look for 2 hours

The car is now un-driveable and sounds like a Citroen 2CV with BMW not able to look at it for another two weeks. To boot I will probably have to get it put on a flat bed to get it o the garage...another load of cash.

Do you think it is ok to drive to the garage i.e. will the ECU have closed down the injector to the effected cylinder to prevent CAT damage?

Apologies for the lengthy post.

Any advice would be more than welcome and thanks in advance for reading this long thread.

Thanks

[firedragon]

Sorry forgot to mention that the car has also been suffering with abnormal gear changes downhill.

It seems to select a higher gear and revs higher than it should when you would expect if to go into a lower gear.

Lastly, do you think it has gone into limp home mode?

Cheers all

[e92_enthusiast_1]

What year and how many miles on your car? What brand coils did you guys install?

[firedragon]

Thanks for your reply.

It is a 2006 with 60,000 miles on the clock.

The coils were not replaced only the plugs, we just moved them around to eliminate from the equation i.e. swopped 1 with 3, 2 with 5, 4 with 6 and all other variations you can think of.

[firedragon]

Sorry, the coils are genuine BMW stock probably from new I expect!!!

[e92_enthusiast_1]

I'm dumb I meant plugs. Did you use OEM Bosch plugs?

[boris]

Can you give us the list of codes stored in the DME?

[e92_enthusiast_1]

I see you have a 2006. I'm not too familiar with that engine and I'm not sure if the OEM plugs were Bosch on that years engine.

Yeah a full list of codes would be very useful too.

[firedragon]

The plugs that we put in were NGK which are listed as suitable, why do you think it could be just the wrong plugs? If it was due to the wrong plugs would it not effect all 6 cylinders rather than one then another.

Regarding the codes I am not sure sorry - I just got told it was a code for a misfire in cylinder 5 and then this cleared and then the last three stated a misfire in cylinder 2.

[firedragon]

Thanks for your help so far guys.

It is 1am here in the UK so I am off to bed now but will check the post in the morning. Just didn't want you thinking I was rude by not answering anymore posts for the next few hours.

[e92_enthusiast_1]

No worries, I am just trying to get as much information as possible about vehicle history and what's been done. Just for everyone who's reading. You never know. Weird issue for sure. Please keep us updated with any details.

[firedragon]

Will do mate.

I tried a static ECU reset this morning by pushing the start button then holding down the accelerator for 30 seconds then pushing the start button again then waiting 30 seconds before starting her up....no change!

Checked the wiring to the coils again and can find no issues...I really think this is now an electrical issue but gonna need the stealership to confirm...great!!!

[Gizm0]

Your issue is you ran the gas tank so low that the fuel pump sucked in the oily residue/gunk that was in your gas tank and clogged one or more injectors... You can try to dump a can of injector cleaner in the gas tank, but if the ECU has already shut down the injector, then that won't help much... You'll either have to remove the injector to clean it or put new injectors in... $$$$

[e92_enthusiast_1]

Interesting. Thx for the heads up on that Gizmo. Didn't know that could happen.

Originally Posted by Gizm0

Your issue is you ran the gas tank so low that the fuel pump sucked in the oily residue/gunk that was in your gas tank and clogged one or more injectors... You can try to dump a can of injector cleaner in the gas tank, but if the ECU has already shut down the injector, then that won't help much... You'll either have to remove the injector to clean it or put new injectors in... $$$$

[firedragon]

Thanks Gizmo for your assistance.

Couple of points - I have ran out of gas completely before [I know, what a tit] and this has not happened but can guess that it could happen anytime the tank gets this low. Would the fuel filter not prevent this from happening?

If the misfire was originally in cylinder 5 then one assumes that this injector was blocked to some degree. Then the misfire went to cylinder 2 so one assumes this injector is now blocked. As cylinder 5 is no longer logged as misfiring then I suppose this could have dislodged any debris itself hence why it is now ok...correct...? In saying this, I thought that once an injector was blocked there was no going back and therefore I would expect both cylinder 2 and 5 to have now been logged as misfiring.

[firedragon]

Gizmo, would a manual reset of the ECU release the injector in question to allow for me to get he cleaner in?

[berne]

how did i go? i have a similar problem

[firedragon]

Hi Berne,

It turned out to be three faulty/duff spark plugs.

Cheers

[firedragon]

By the way, the injector will shut down even if it is just a plug issue to ensure the CAT is kept from burning out.

[kunal_d]

There are many cases where not using original BMW branded plugs on these cars will cause misfires like this.

[Gizm0]

Originally Posted by kunal_d

There are many cases where not using original BMW branded plugs on these cars will cause misfires like this.

The Bosch are $30 cheaper than the BMW for a set of 6 and perform just as good...

Bosch... http://www.ecstuning.com/BMW-E92-335...lugs/ES257800/

BMW... http://www.ecstuning.com/BMW-E92-335...ugs/ES2681429/

[firedragon]

The plugs that failed were Bosch plugs...NGK had the same issues. Very strange but could be down to how they were fitted.

BMW OEM plugs are Bosch plugs.