[jkwhar]

I know this isn't an F15 subforum but I think there's more activity here then the f15 side but it's the same engine.

Hey all, the symptoms are mildly rough idle/misfire when starting up from a warm engine for about 10 seconds. I can also feel it while cruising on a highway (this happens very rarely and when it does happen, its so mild that sometimes I cant tell if its the crappy NJ roads or the engine). I've been chasing this issue for a few weeks now.

2014 F15 N55 with 120,xxx miles. To add, I don't/can't remember having this issue before I had the car get its oil pan gasket and OFHG replaced. I've checked from what I can think/figure/find on youtube/tutorials the shop would've removed to make sure they didn't forget anything.

What I have done/checked:
-changed sparkplugs - NGK 97506
-changed coilpacks -Delphi
-Checked ISTA and no faults/codes stored.
-Did a smoke test after the air filter to rule out leaks, nothing.
-ran misfire test plan on ISTA, nothing found.
-Did a misfire counter, and the count is random and jumps between cylinders (again, this only within the first 10 seconds)
Cyl1-1 count
Cyl3- 6 counts
And a minute or 2 later, I saw Cyl3- 1 count.

-I checked the rail pressure comparing it to the set point value and its very close to each other.
-Changed the spark plugs and air filter back in 11/2021
-reset adaptation
-recalibrate the valvetronic, 450cycles

I'm leaning towards fuel or air issue since the misfire jumps between cylinders.

I am probably forgetting 1 or 2 other things I've checked.

Any thoughts on what to check next? And, is there a misfire counter that doesn't reset on its own if it doesn't detect a misfire? It would be nice to get a misfire count on a long drive to see if the misfire happens in any other cylinders.

Thanks in advance!


EDIT 1:
3/26/24- Changed both vanos solenoids and the problem still exists. I'm going to check the injectors to see if they are leaking.

[thejeremyman9]

original coils?

[jkwhar]

Originally Posted by thejeremyman9

original coils?

Yup, I ruled it out since the misfire happens in random cylinders. I did put in an order for bosch coils so I'll swap them out just to rule it out for sure.

[thejeremyman9]

Some people have had luck using techron fuel system cleaner with similar very mild symptoms and initial rough idles. Use 1 bottle per tank and run 1-2 tanks in a row. https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1
BMW uses this same bottle rebranded

[jkwhar]

Originally Posted by thejeremyman9

Some people have had luck using techron fuel system cleaner with similar very mild symptoms and initial rough idles. Use 1 bottle per tank and run 1-2 tanks in a row. https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1
BMW uses this same bottle rebranded

I'll give that a try. Last I used was Liquimoly DI Jectron Fuel Injection Cleaner Nov/21.

[F15_SGM]

It's Your coil pack. Mine is also an n55 f15. I also replaced the plugs it didn't fix it. Had to swap spark plugs to NGK 97506 as the bosch zr5tpp33 is no good and put in a fresh pack of Delphi coil pack. You won't get any codes regarding this, and swapping them from cylinder to cylinder won't change anything as your whole pack is weak. Your plugs will need to replace same time as well, and highly recommend not using the OE bosch. Only use NGK or OEM BMW Bosch.

Also, don't just start doing adaptions and calibrations. Those are only meant to do when replacing and installing new parts for those certain items. It is not good for wear as it resets calibration on them as it has zero wear/new part.

Here is more information regarding the trash bosch plugs. https://f15.bimmerpost.com/forums/sh....php?t=2014403

[jkwhar]

Originally Posted by F15_SGM

It's Your coil pack. Mine is also an n55 f15. I also replaced the plugs it didn't fix it. Had to swap spark plugs to NGK 97506 as the bosch zr5tpp33 is no good and put in a fresh pack of Delphi coil pack. You won't get any codes regarding this, and swapping them from cylinder to cylinder won't change anything as your whole pack is weak. Your plugs will need to replace same time as well, and highly recommend not using the OE bosch. Only use NGK or OEM BMW Bosch.

Also, don't just start doing adaptions and calibrations. Those are only meant to do when replacing and installing new parts for those certain items. It is not good for wear as it resets calibration on them as it has zero wear/new part.

Here is more information regarding the trash bosch plugs. https://f15.bimmerpost.com/forums/sh....php?t=2014403

I really hope it's as simple as coil packs. So you had similar symptoms as mine where its random cylinder misfire? And thanks for the heads up on the adaptation/calibrations.

And looks like I'm running Bosch ZR5TPP33. I'll order a set of NGK 97506 and swap them later. The Bosch coil packs should be delivered tomorrow.

Thanks!

[F15_SGM]

Originally Posted by jkwhar

I really hope it's as simple as coil packs. So you had similar symptoms as mine where its random cylinder misfire? And thanks for the heads up on the adaptation/calibrations.

And looks like I'm running Bosch ZR5TPP33. I'll order a set of NGK 97506 and swap them later. The Bosch coil packs should be delivered tomorrow.

Thanks!

The bosch coil pack will also give you trouble. You will need a set of Quality Delphi coil pack. The bosch coils are not good coils for N55. Only Delphi N55 or Eldor S55 coils will work good.

[thejeremyman9]

Originally Posted by F15_SGM

It's Your coil pack. Mine is also an n55 f15. I also replaced the plugs it didn't fix it. Had to swap spark plugs to NGK 97506 as the bosch zr5tpp33 is no good and put in a fresh pack of Delphi coil pack. You won't get any codes regarding this, and swapping them from cylinder to cylinder won't change anything as your whole pack is weak. Your plugs will need to replace same time as well, and highly recommend not using the OE bosch. Only use NGK or OEM BMW Bosch.

Also, don't just start doing adaptions and calibrations. Those are only meant to do when replacing and installing new parts for those certain items. It is not good for wear as it resets calibration on them as it has zero wear/new part.

Here is more information regarding the trash bosch plugs. https://f15.bimmerpost.com/forums/sh....php?t=2014403

Stock bosch plugs at stock gap are better than the NGKs for 99% of applications unless you truly need a colder plug and a smaller gap for a pretty serious build. This has been discussed to death in the N55 tech forum. You want the hottest plug with the largest gap your car can support. It sounds like you had a bad experience with the bosch plugs but that doesnt mean they are no good, and going to a colder plug with a smaller gap can actually be worse when its not actually needed for the application.

[F15_SGM]

Originally Posted by thejeremyman9

Stock bosch plugs at stock gap are better than the NGKs for 99% of applications unless you truly need a colder plug and a smaller gap for a pretty serious build. This has been discussed to death in the N55 tech forum. You want the hottest plug with the largest gap your car can support. It sounds like you had a bad experience with the bosch plugs but that doesnt mean they are no good, and going to a colder plug with a smaller gap can actually be worse when its not actually needed for the application.

No need to cheap out on plugs, Platinum vs Iridium. The part number is not even the same. Most of everyone that still claims bosch is good have the zr5tpp33-S variant, and they think it's the zr5tpp33. As examples in the link in my prior post, people were posting zr5tpp33-s and saying they have zr5tpp33. The zr5tpp33 are nothing but trouble after some time. You can only purchase the zr5tpp33-s with BMW stamped Bosch. Also, the OP also has zr5tpp33. Same symptoms as mine with weak coils. NGK is a far superior brand than bosch in the plug world, and The OEM plug for a 4-cylinder N20 is also the same NGK 97506. From my experience using the NGKs, the engine is smoother than ever before, even comparing them to my OEM Plugs zr5tpp33-s. Although if your car calls for it, then why not. You don't need to gap them for a stock application. The quality control on bosch products is no good nowadays. I read everything prior to getting that zr5tpp33 and wish I never listened to anybody that supports bosch plugs or anyone saying they are the same as Oem. I only replaced them as preventive as my OEM BMW zr5tpp33-s were still great with 90K on them. When I swapped the zr5tpp33 for another one, they exhibit the same behavior as OP after a short amount of time as well. After further research, its something to do with Quality control and the tighter electrode gap and larger internal resistor that dissipates heat faster/ground differences between zr5tpp33 and zr5tpp33-s. As I said, some cars just call for it. Also, mine are gapped to 0.020, and I'm only stage 1 bm3 nothing serious, and have no issues at all. If you absolutely don't want ngk not sure why not though, but you can get the BMW OEM plugs that are bosch zr5tpp33-s.

https://www.bimmerfest.com/threads/c.../post-13410647

Thread #19.

[thejeremyman9]

Originally Posted by F15_SGM

No need to cheap out on plugs, Platinum vs Iridium. The part number is not even the same. Most of everyone that still claims bosch is good have the zr5tpp33-S variant, and they think it's the zr5tpp33. As examples in the link in my prior post, people were posting zr5tpp33-s and saying they have zr5tpp33. The zr5tpp33 are nothing but trouble after some time. You can only purchase the zr5tpp33-s with BMW stamped Bosch. Also, the OP also has zr5tpp33. Same symptoms as mine with weak coils. NGK is a far superior brand than bosch in the plug world, and The OEM plug for a 4-cylinder N20 is also the same NGK 97506. From my experience using the NGKs, the engine is smoother than ever before, even comparing them to my OEM Plugs zr5tpp33-s. Although if your car calls for it, then why not. You don't need to gap them for a stock application. The quality control on bosch products is no good nowadays. I read everything prior to getting that zr5tpp33 and wish I never listened to anybody that supports bosch plugs or anyone saying they are the same as Oem. I only replaced them as preventive as my OEM BMW zr5tpp33-s were still great with 90K on them. When I swapped the zr5tpp33 for another one, they exhibit the same behavior as OP after a short amount of time as well. After further research, its something to do with Quality control and the tighter electrode gap and larger internal resistor that dissipates heat faster/ground differences between zr5tpp33 and zr5tpp33-s. As I said, some cars just call for it. Also, mine are gapped to 0.020, and I'm only stage 1 bm3 nothing serious, and have no issues at all. If you absolutely don't want ngk not sure why not though, but you can get the BMW OEM plugs that are bosch zr5tpp33-s.

https://www.bimmerfest.com/threads/c.../post-13410647

Thread #19.

Not here to argue, just saying that that this exact thing - the bosch with the S vs. without the S vs. the NGKs and related discussions on gap has happened countless times over the last several years. The bosch without the S are just fine. I am running them, have been for years, on MHD stage 2+ 91 octane and E20 using E30 fuel. OP can read N55 tech forums if he wants or just pick. Nothing is necessarily WRONG with the NGKs, but the issue is running a colder plug with a smaller gap if you dont need it. Short trips and lower power level with gold plugs and small gap and caused fouled plugs. And in general, you want the largest gap you can for good combustion

[jkwhar]

Originally Posted by F15_SGM

The bosch coil pack will also give you trouble. You will need a set of Quality Delphi coil pack. The bosch coils are not good coils for N55. Only Delphi N55 or Eldor S55 coils will work good.

Which Delphi coils are you running? I'm seeing 2 or 3 model numbers.

[F15_SGM]

Originally Posted by jkwhar

Which Delphi coils are you running? I'm seeing 2 or 3 model numbers.

https://www.fcpeuro.com/products/bmw-ignition-coil-kit-set-of-6-12138616153kt1

[jkwhar]

Originally Posted by F15_SGM

https://www.fcpeuro.com/products/bmw-ignition-coil-kit-set-of-6-12138616153kt1

Order is in!

[jkwhar]

Changed all 6 coils with Delphi and didn't fix the issue.

Edit: I'm going to order a set of NGK 97506 spark plugs and see if theres any difference.

[F15_SGM]

Originally Posted by jkwhar

Changed all 6 coils with Delphi and didn't fix the issue.

Edit: I'm going to order a set of NGK 97506 spark plugs and see if theres any difference.

Yes, do both at same time. Also i wouldn't put the new coils on with bad plugs just incase it shorts the new coil. Hopefully the new plugs will resolve everything.

[jkwhar]

Swapped the plugs, no change.

[thejeremyman9]

Only hot start right, not cold start?

[jkwhar]

Yup. It could also be bc during cold start, the rpm’s are much higher.

Outside of the starting up at warm, can drives perfectly. WOT no issues.

[Orion4]

Did you ever run the Techron a couple of tank fulls to see if that aids?

[jkwhar]

Originally Posted by Orion4

Did you ever run the Techron a couple of tank fulls to see if that aids?

I picked up a bottle. Going to add it tomorrow after I fuel up.

After thinking what else to check, I decided to check the TMAP sensor. I'm certain it's not the MAF because unplugging it makes no difference. Ran a test plan that shows the reading of ambient, charge pipe and intake mani pressure.

It ISTA it says +-25 deviation is fine but I'm getting -50's while the engine is idling. Also, the "setpoint value for the intake pipe vacuum" was blank.

[F15_SGM]

Okay, I think next step would be to investigate the injectors. Try techron if no change it's another issue. Can you describe what you feel when driving more in depth? Have you checked for any vacuum leaks?

Crankcase Ventilation hose is very common to be broken and many other brittle plastic hoses.