misfire? need suggestions

[Danishp97]

https://youtube.com/shorts/D0OG7fgJMbA?feature=share

Hello everyone. I bought the car 8 months back roughly 24,000 kms on the odo.
Did an oil change, filter change etc. car already had a custom stage 2 tune when I bought it. Previous owner had done spark plugs (oem gapped properly) when tuning the car at 20,000 kms.

After I got the car I did injectors and coils together as preventive maintenance. Everything was fine. However 2000 kms post all this I blew one fuel rail. Followed by the second one a week later.
We installed new fuel rails. Car was driving fine until 500 kms later injector 8 started to leak from TOP.
Temporarily put the 8th injector from my previous injectors that were taken off the car and called in for a replacement. Everything was okay and i went for a good 200 kms drive post which when I got home the car started to sound like misfire at idle. Decided not to drive until the replacement injector 8 is here. Got the replacement injector, installed it, but the misfire like sound at idle is still there. Scanned for codes car has no codes. Misfire counter reads 0. Cylinder smoothness test shows Cylinder number 6 running rough. Value is somewhere near 5. I swapped the coils and plugs from cylinder 5 to cylinder 6 to see if there’s any difference but no difference as such. No codes, and smoothness test shows cylinder 6 running rough. Today I went for a drive again, clocked 282kmph easily without any hiccup, car pulls proper. Only when I stop and it idles I can hear my exhaust pop intermittently and feel a vibration/hiccup of sort under my seat.
One thing I realised that when I cold start the car it does not misfire until the cold start settles.

Is it a vacuum leak? Failing lpfp? A little lost at this point as it drives PROPER.

Car’s odo is at 28,000 kms and it’s a 2013 car. Any help is appreciated!

[rorz12]

Originally Posted by Danishp97

https://youtube.com/shorts/D0OG7fgJMbA?feature=share

Hello everyone. I bought the car 8 months back roughly 24,000 kms on the odo.
Did an oil change, filter change etc. car already had a custom stage 2 tune when I bought it. Previous owner had done spark plugs (oem gapped properly) when tuning the car at 20,000 kms.

After I got the car I did injectors and coils together as preventive maintenance. Everything was fine. However 2000 kms post all this I blew one fuel rail. Followed by the second one a week later.
We installed new fuel rails. Car was driving fine until 500 kms later injector 8 started to leak from TOP.
Temporarily put the 8th injector from my previous injectors that were taken off the car and called in for a replacement. Everything was okay and i went for a good 200 kms drive post which when I got home the car started to sound like misfire at idle. Decided not to drive until the replacement injector 8 is here. Got the replacement injector, installed it, but the misfire like sound at idle is still there. Scanned for codes car has no codes. Misfire counter reads 0. Cylinder smoothness test shows Cylinder number 6 running rough. Value is somewhere near 5. I swapped the coils and plugs from cylinder 5 to cylinder 6 to see if there’s any difference but no difference as such. No codes, and smoothness test shows cylinder 6 running rough. Today I went for a drive again, clocked 282kmph easily without any hiccup, car pulls proper. Only when I stop and it idles I can hear my exhaust pop intermittently and feel a vibration/hiccup of sort under my seat.
One thing I realised that when I cold start the car it does not misfire until the cold start settles.

Is it a vacuum leak? Failing lpfp? A little lost at this point as it drives PROPER.

Car’s odo is at 28,000 kms and it’s a 2013 car. Any help is appreciated!

Just a few ideas:-

1- did you make note of the unique 3 digit codes on the side of each injector and program them in ISTA after replacing your injectors? If you didn't account for the factory offsets per injector, it will not run smooth. If you haven't done this, you will have to remove each injector, make note of the digits and in which cylinder number it is located, reinstall them and then code them in ISTA (engine off) directly afterwards.

2- did you make sure you got the correct injector (EU5 or EU6)? ISTA can identify which version you need. Given it's a 2013, it's probably EU5.

3- did you replace all the old decoupling elements with new ones as well?

[Danishp97]

Originally Posted by rorz12

Just a few ideas:-

1- did you make note of the unique 3 digit codes on the side of each injector and program them in ISTA after replacing your injectors? If you didn't account for the factory offsets per injector, it will not run smooth. If you haven't done this, you will have to remove each injector, make note of the digits and in which cylinder number it is located, reinstall them and then code them in ISTA (engine off) directly afterwards.

2- did you make sure you got the correct injector (EU5 or EU6)? ISTA can identify which version you need. Given it's a 2013, it's probably EU5.

3- did you replace all the old decoupling elements with new ones as well?

Hi, yes injector flow rates were coded after the install. Injectors are EU5 and yes the decoupling elements were changed too.

[rorz12]

Originally Posted by Danishp97

Hi, yes injector flow rates were coded after the install. Injectors are EU5 and yes the decoupling elements were changed too.

Could be worth double checking the values, especially on cylinder 6. But it's a bit of a pain of a job to redo all, and you would have to replace the teflon seal once you remove an injector. I would say at least double check that injector 6 is seated and sealed correctly and cross check the flow rate value.

So the car was running and idling smoothly after you replaced injectors and coils but you only started getting this problem after the fuel rails blew? A bit odd that a fuel rail would blow with 20K KM on the ODO and the second one the following week. Have you checked that the pressure is fine in both rails?

Do you know anything about the car history? Was it sitting for a long period before purchasing? 20K KM for a 2013 is nothing.

[Danishp97]

Originally Posted by rorz12

Could be worth double checking the values, especially on cylinder 6. But it's a bit of a pain of a job to redo all, and you would have to replace the teflon seal once you remove an injector. I would say at least double check that injector 6 is seated and sealed correctly and cross check the flow rate value.

So the car was running and idling smoothly after you replaced injectors and coils but you only started getting this problem after the fuel rails blew? A bit odd that a fuel rail would blow with 20K KM on the ODO and the second one the following week. Have you checked that the pressure is fine in both rails?

Do you know anything about the car history? Was it sitting for a long period before purchasing? 20K KM for a 2013 is nothing.

Hi, history is that the previous owner never used to rip it etc. he would occasionally put a lower grade of fuel even after the tune. So what I did is change injector and coils. Car was driving absolutely fine
Even after changing the rails. This issue only start once the injector 8 started to leak fuel from top and car started to reek of gas smell. So we installed one old injector temporarily until replacement came. After installing the old injector too the car was driving fine until same night it started to misfire like my video i have attached. So then I chose not to drive it until replacement came. After installing the replacement injector too this misfire at idle is still there. When you scan the misfire counter shows 0. If you run cylinder roughness test it shows cyl 6 running rough. So we switched coils and plugs over from cyl 5. Still the same no luck no improvement. However the car is making proper boost drives proper pulls like a train. ONLY at idle is this popping noise from exhaust and vibration and hiccup. I even clocked 280km/hr last night without any hiccups.

[rorz12]

Originally Posted by Danishp97

Hi, history is that the previous owner never used to rip it etc. he would occasionally put a lower grade of fuel even after the tune. So what I did is change injector and coils. Car was driving absolutely fine
Even after changing the rails. This issue only start once the injector 8 started to leak fuel from top and car started to reek of gas smell. So we installed one old injector temporarily until replacement came. After installing the old injector too the car was driving fine until same night it started to misfire like my video i have attached. So then I chose not to drive it until replacement came. After installing the replacement injector too this misfire at idle is still there. When you scan the misfire counter shows 0. If you run cylinder roughness test it shows cyl 6 running rough. So we switched coils and plugs over from cyl 5. Still the same no luck no improvement. However the car is making proper boost drives proper pulls like a train. ONLY at idle is this popping noise from exhaust and vibration and hiccup. I even clocked 280km/hr last night without any hiccups.

Did you ever figure this out? Ironically enough, I now have a problem with cylinder 6 misfiring on my 2013 650i..

My injectors, coils, spark plugs and HPFPs are all new yet I get misfires on cylinder 6 at cruise speed of around 105 KMPH. Above and below that speed, it goes away. In sport mode doesn't misfire. Also get some misfires after shifting from 2-3 and 3-4.

Another weird thing is all my misfires go away if I disconnect the MAF sensors. MAF sensors are brand new though..

I've switched around everything and it still stays in cylinder 6. Compression on all cylinders is good and around 210 psi average. Highest being 217 psi and lowest 205 psi.

I've seen an airmass plausibility code A few times but I've smoke tested for leaks and nothing showed up.