Misfires on cyl 6 on heavy load - Z4 35is MHD 2+

[Peter55]

Hey guys, I'm trying to solve misfires on cyl 6 on heavy loads.

My car is Z4 E89 35is with DCT and around 80k mileage.

Problem started to show after stage 2+ from mhd, it appears on continuous heavy load (flooring) and higher gears. I noticed it more often on hot day.

I've done the following since then:
1. NGK 97506 spark plugs with 0.020'' gap
2. New Delphi coils
3. Walnut blast intake port cleanup
4. Injector check for leaks - no leaks, new seals and replaced cyl 6 with cyl 2 - still misfire on 6
5. Walbro 450 lpfp
6. EKP with additional themopads (didn't know walbro 450 overheats ekp)
7. 3.5 bar map sensor with flashing

I plan to go with single turbo setup, so I'd done those things either way.

Additional mods:
1. Wagner Evo 3 IC
2. Catless downpipes
3. DCI
4. MHD + xhp
5. Vrsf charge pipe with HKS bov
6. Golf tee mod, exhaust flap can't close so I've plugged the vacuum hose for now

I've checked the compression on cold motor, here are the results:
1. 159.5 psi
2. 181.3 psi
3. 181.3 psi
4. 159.5 psi
5. 177.0 psi
6. 181.3 psi

Logs with pulls (no missfire errors): log1 log2
Log on stationary with small load increase: log

My suspision is hpfp, in my opinion repeating misfire on 6 cyl could be caused by the lack of fuel pressure.
I wanted to ask - is there something in logs to support that? Or something I should have check before hpfp change?

Another issue are high LTFT on idle, around 20% on bank 1 and over 20% on bank 2 - here I also suspect hpfp or walbro 450 messing with EKP settings. That one came recently.

May I ask for some help from you?

 

[pbondar]

Will be interested in the gurus views…

 

[RTA]

Please put your logs on datazap or on this website.
Log at least the hpfp and lpfp channels next to the usual.
Dipping and afr ratio issues could indicate fueling issues.

As you replace plugs etc, I think your pump might be on it's way out.
You could, longer shot, also have electric issues, check the dynamo and battery for correct voltages and operation.

But better to see your logs...

Also please make a full pull in 3rd from 2000 up to 7k. Traction control full off.

 

[Peter55]

Please put your logs on datazap or on this website.
Log at least the hpfp and lpfp channels next to the usual.
Dipping and afr ratio issues could indicate fueling issues.

As you replace plugs etc, I think your pump might be on it's way out.
You could, longer shot, also have electric issues, check the dynamo and battery for correct voltages and operation.

But better to see your logs...

Also please make a full pull in 3rd from 2000 up to 7k. Traction control full off.

In Z4 there's no lpfp pressure sensor.

I've made 2 logs with MHD, I don't see there additional hpfp params beside rail pressure. Maybe protool would have more.
First run was without limp mode, but I could feel under my foot that something was not right.
Second run was with the limp mode
log1 log with limp mode
I noticed very high EGT, is there a limiter based on that parameter in n54?

 

[pbondar]

Well your HPFP profile with rpm varies differently to mine…

V17 datalog adjusted to reduce timing corrections

www.spoolstreet.com

 

[Peter55]

Well your HPFP profile with rpm varies differently to mine…

V17 datalog adjusted to reduce timing corrections

www.spoolstreet.com

I see, how does your fuel setup look like? Overdrive? LPFP upgraded?

 

[pbondar]

I see, how does your fuel setup look like? Overdrive? LPFP upgraded?

Bog stock 14 year old, 70k mile HPFP with a Walboro 435 with upgraded EKP

 

[RTA]

Your cyl 6 gives 3.3 degree correction at around 6k rpm.
Thereafter your bank 2 start correcting to avoid damage etc.
im not sure the minimum required, lasy to check,, so check for the minimum hpfp pressure, but you should check your cyl 6 plugs/injectors etc...
Octane is good?
You could, if the parts for cyl6 are new/good, consider to reset your adaptions and perform the correct re-adaption procedure. (Its documented online)
This assuming you do not have a direct mechanical issue, but first check for mechanical/part related issues.
Next, you could also return a stage lower, and log that. This to see the diff.
Dont beat the car, too extensive, given something might be off..

 

[Peter55]

Your cyl 6 gives 3.3 degree correction at around 6k rpm.
Thereafter your bank 2 start correcting to avoid damage etc.
im not sure the minimum required, lasy to check,, so check for the minimum hpfp pressure, but you should check your cyl 6 plugs/injectors etc...
Octane is good?
You could, if the parts for cyl6 are new/good, consider to reset your adaptions and perform the correct re-adaption procedure. (Its documented online)
This assuming you do not have a direct mechanical issue, but first check for mechanical/part related issues.
Next, you could also return a stage lower, and log that. This to see the diff.
Dont beat the car, too extensive, given something might be off..

Thanks for the answers, coils, Spark pług are new, injector swapped with 2 cyl, coded, adaptations cleared. The issue remains the same and on the same cylinder. I've tried multiple fuels.
I don't have data for minimum hpfp pressure for 6000rpm, but i checked other logs on spoolstreet and it is lower at least for 30 bar.

 

[RTA]

Swap in 3 steps coil, plug and injector between cyl 5 and 6, see if the issue follows these changes. Before: check if all is currently installed per torque spec and if there is no damage in the sleaves, seals etc.. tiny scratches or leaks can cause this too.
Also do a compression test on all cyl's and compare them and against the required compression spec. Can be found with google.. bmw n54 manual or 335i bentley manual. Also check all cyl 6 wiring for damages..
When all done, consider the re-adaption. Not before these checks have been done.

 

[Peter55]

Swap in 3 steps coil, plug and injector between cyl 5 and 6, see if the issue follows these changes. Before: check if all is currently installed per torque spec and if there is no damage in the sleaves, seals etc.. tiny scratches or leaks can cause this too.
Also do a compression test on all cyl's and compare them and against the required compression spec. Can be found with google.. bmw n54 manual or 335i bentley manual. Also check all cyl 6 wiring for damages..
When all done, consider the re-adaption. Not before these checks have been done.

I did all of that as I wrote in the first post, issue still occurs.
About which adaptation are you exactly talking about?

 

[RTA]

Sorry, im responding from my phone.

BMW N series petrol engines adaptations N43 N46 N52 N53 N54

BMW N series petrol engines adaptations N43 N46 N52 N53 N54

bimmerprofs.com

 

[RTA]

Sorry, im responding from my phone.

BMW N series petrol engines adaptations N43 N46 N52 N53 N54

BMW N series petrol engines adaptations N43 N46 N52 N53 N54

bimmerprofs.com

While you did replace, one off the new parts could be off.. given the persitence of cyl 6, i would still test by moving to cyl 5 again.
Also, double check the coding of the injector on cyl 6.. you might have an potential exotic cause, so i just give you my thoughts on possible assessment steps.

You could also check with a scope the cyl wall of 6, sometime it could have issues without direct compression loss.
You could also check the coloring of your plugs and check if the one of cyl6 differs. Colors could give a hint.
Also the mosfet on the ecu for cyl6 could be off.
Also a dipp off the low pressure fuel system could cause this, however you would have other side effects too in the meanwhile.
Electric issues can cause missfires too, but that causes in general missfires on random cylinders, not stick to cyl 6.

 

[NoGuru]

DCT has a dual mass flywheel and the bushing tend to wear out and create vibrations in the higher RPM's.

I had this issue and installed an M4 single mass and it resolved the misfire.

 

[Peter55]

While you did replace, one off the new parts could be off.. given the persitence of cyl 6, i would still test by moving to cyl 5 again.
Also, double check the coding of the injector on cyl 6.. you might have an potential exotic cause, so i just give you my thoughts on possible assessment steps.

You could also check with a scope the cyl wall of 6, sometime it could have issues without direct compression loss.
You could also check the coloring of your plugs and check if the one of cyl6 differs. Colors could give a hint.
Also the mosfet on the ecu for cyl6 could be off.
Also a dipp off the low pressure fuel system could cause this, however you would have other side effects too in the meanwhile.
Electric issues can cause missfires too, but that causes in general missfires on random cylinders, not stick to cyl 6.

Thanks, no matter what I change issue occurs always on 6, I hot my hands on another hpfp and it's still the same. I have msd81, so there should be no issues with injectors mosfets, but are ignition mosfest prone to damage?

 

[Peter55]

DCT has a dual mass flywheel and the bushing tend to wear out and create vibrations in the higher RPM's.

I had this issue and installed an M4 single mass and it resolved the misfire.

Thanks, stock M4 has single mass flywheel?
What misfire did you have?

 

[RTA]

But will a flywheel issues only affect 6?

 

[RTA]

Thanks, no matter what I change issue occurs always on 6, I hot my hands on another hpfp and it's still the same. I have msd81, so there should be no issues with injectors mosfets, but are ignition mosfest prone to damage?

Did you had a chance to check the color of the plug?

 

[NoGuru]

But will a flywheel issues only affect 6?

Yes, its the cylinder right next to the flywheel/

I did mine two years ago, works great and spins faster.