[Shmooples]

Hey guys, so I recently decided to pull the trigger and get a jb4 for my stock 2008 335i (60k miles). I changed out all of the spark plugs to NGK 95770 (gapped to .022) prior to the install and everything seemed to run alright for some time. However, I was on the highway recently, dropped gears, and went WOT (like I've done in the past) and suddenly I got a CEL. Sure enough, it looks like a misfire developed for cylinders 1 & 2. Fast forward to me trying to troubleshoot. I swapped my coil packs from 3 & 4 to 1 & 2, still misfiring. I wouldn't imagine its the spark plug, because they are brand new, but I swapped the plugs from 1 & 2 to the oem bosch plugs that were in the engine. Misfire seemed to be gone while the jb4 was set to map 0 and at a low rpm, but still occured during WOT, however only cylinder 2 was misfiring this time. Not really sure what the issue might be? Any help would be a godsend at this point as I am still new to tuning. Thanks!

[jeddo45]

Originally Posted by Shmooples

Hey guys, so I recently decided to pull the trigger and get a jb4 for my stock 2008 335i (60k miles). I changed out all of the spark plugs to NGK 95770 (gapped to .022) prior to the install and everything seemed to run alright for some time. However, I was on the highway recently, dropped gears, and went WOT (like I've done in the past) and suddenly I got a CEL. Sure enough, it looks like a misfire developed for cylinders 1 & 2. Fast forward to me trying to troubleshoot. I swapped my coil packs from 3 & 4 to 1 & 2, still misfiring. I wouldn't imagine its the spark plug, because they are brand new, but I swapped the plugs from 1 & 2 to the oem bosch plugs that were in the engine. Misfire seemed to be gone while the jb4 was set to map 0 and at a low rpm, but still occured during WOT, however only cylinder 2 was misfiring this time. Not really sure what the issue might be? Any help would be a godsend at this point as I am still new to tuning. Thanks!

With misfires, it usually goes in this order:

1. Spark plugs
2. coil packs
3. Fuel injectors

I'd get all new coil packs and test injectors next.

[Shmooples]

Originally Posted by jeddo45

With misfires, it usually goes in this order:

1. Spark plugs
2. coil packs
3. Fuel injectors

I'd get all new coil packs and test injectors next.

Yeah, i'm sort of leaning towards that as the answer. Just seemed weird that the misfire didn't follow the coils after I swapped them to a cylinder that didn't misfire...

[dcorn]

Walnut blast?

I just got my valves cleaned and every bit of hesitation/misfiring under boost went away.

[chuckn0rr1s]

Once upon a time I had a similar issue but on a stock E90 335. I ended up swapping out all of the coils even though they all tested fine. it was a small enough misfire that the CEL would not illuminate but strong enough to notice it under WOT. My point is even though the coils may seem like they are ok they might not be.

[Shmooples]

Originally Posted by dcorn

Walnut blast?

I just got my valves cleaned and every bit of hesitation/misfiring under boost went away.

I was thinking about that. @ 60k miles, im not sure the previous owner had it done once. Did your misfiring just come on after running it hard or was it brought on incrementally? Also, how much did it end up costing to get it done?

[Shmooples]

Originally Posted by chuckn0rr1s

Once upon a time I had a similar issue but on a stock E90 335. I ended up swapping out all of the coils even though they all tested fine. it was a small enough misfire that the CEL would not illuminate but strong enough to notice it under WOT. My point is even though the coils may seem like they are ok they might not be.

Yeah, that would make sense considering I just changed out the plugs before the jb4 and not the coils. If all else fails, i'll get some new coils by the end of the week.

[HB E90]

Originally Posted by Shmooples

Yeah, that would make sense considering I just changed out the plugs before the jb4 and not the coils. If all else fails, i'll get some new coils by the end of the week.

Just wondering if you got the new coils and if that fixed it. I recently installed MHD and started getting misfires on cyl #3. It did move to cyl#2 after swapping so hopefully just one bad coil? Should get it today. I have a new set of NGK plugs coming also but will do later if its good after new coil.

[Shmooples]

Originally Posted by HB E90

Just wondering if you got the new coils and if that fixed it. I recently installed MHD and started getting misfires on cyl #3. It did move to cyl#2 after swapping so hopefully just one bad coil? Should get it today. I have a new set of NGK plugs coming also but will do later if its good after new coil.

Well in my case, it turned out to be bad injectors. Had to take it to the dealer to get all 6 replaced. After though, everything ran great! However, for you, it definitely does sound like the coils are bad if the misfire is moving. When I was having issues, my misfire did not move after changing the coils.

Good luck to you!