[Randy Johnson]

I've got a 435i with just under 60k miles. Never had an issue with the engine until now. Drove the car all day Saturday and parked it around 5 pm. Go out around 9:30 on Sunday morning and the car starts running rough. It started fine and I didn't notice the rough running until about 3 minutes into the drive. My low gas indicator just came on so I figured I may need gas. I've run it below this level many time before without issue but filled up anyway. Filling up gas tank did not help. I also only use 93. Took the car home and decided to check the spark plugs for any abnormalities. All plugs looked fine. They are 1 step colder ngk recommended with BM3. I've been tuned stage 1 for about 15k miles. Put the plugs back in and started the car and it still sounds like it was on 4 cylinders not 6. Car runs rough in neutral and in gear. Makes no difference. No lights or indicators on dash. Not sure what else to check. Suggestions please.

2015 435i
60k miles
BM3 stage 1 for 15k miles

[ooshnoo]

Replace plugs and ignition coils
Clean MAF sensor
Clean throttle body

[Randy Johnson]

Thanks. I will try cleaning the maf sensor and throttle body before replacing any parts. I'll research on how to test the ignition coils before replacing. Spark plugs look good.

[Randy Johnson]

I was able to get these codes from bm3.

[Randy Johnson]

Anybody else? Haven't been able to drive the car for 3 days now. Might have to break down and go to the dealer!!!

[dmaxdmax]

I'd look at the electrical system, starting with the battery. Check its voltage with multimeter or cluster (onboard obdii).

Your codes didn't seem to indicate a particular cylinder misfiring, but just voltage issues.

Maybe you just need a battery--if it was an alt issue, you'd see a battery light.

[silver28]

I'm no expert but check out your valvetronic actuator and see if it's leaking or if there's a bad connection. This is a good thread.
https://f30.bimmerpost.com/forums/sh....php?t=1717670


Check this article out too which talks about valvetronic issues.
https://www.autoscopecarcare.com/car...ses-and-fixes/

[Randy Johnson]

Originally Posted by dmaxdmax

I'd look at the electrical system, starting with the battery. Check its voltage with multimeter or cluster (onboard obdii).

Your codes didn't seem to indicate a particular cylinder misfiring, but just voltage issues.

Maybe you just need a battery--if it was an alt issue, you'd see a battery light.

I haven't really driven the car in 3 days. I checked the battery voltage engine off and it was 12.50. Engine running voltage was 14.38. Car starts right up just seems to be running on less than all 6 cylinders. You can also smell unburnt fuel. No check engine lights on dash.

[Randy Johnson]

Originally Posted by silver28

I'm no expert but check out your valvetronic actuator and see if it's leaking or if there's a bad connection. This is a good thread.
https://f30.bimmerpost.com/forums/sh....php?t=1717670


Check this article out too which talks about valvetronic issues.
https://www.autoscopecarcare.com/car...ses-and-fixes/

Thank you Silver. I am checking these links now. Will check the connection at lunch today.

[Randy Johnson]

I checked what was suggested. Battery seems fine. Valvetronic actuator connector looks fine. No oil or damage noticed. Disconnected, cleaned and reconnected. No change. I cannot find a broken or damaged wire anywhere. Checked all the fuses could find and all were good. Not sure if there are relays and where they are located.

[Randy Johnson]

Starting to believe the bmw reliability rumor's.

[rogerdiaz]

Any updates?

I would take it to a reputable indy bmw shop.

[Randy Johnson]

Update is the car still runs like shit. I can't find anything wrong and I still don't have a cell on the dash. Seems to be down 2 cylinders. Can't drive it. If I can't figure it out in a couple of days I'll take it to a mechanic. I just fear it's gonna cost thousands.

[thejeremyman9]

Originally Posted by Randy Johnson

Update is the car still runs like shit. I can't find anything wrong and I still don't have a cell on the dash. Seems to be down 2 cylinders. Can't drive it. If I can't figure it out in a couple of days I'll take it to a mechanic. I just fear it's gonna cost thousands.

Did you uninstall bm3? There's talk that it can suppress CELs, especially for misfires. Has been reported by several people. Once they uninstalled/flashed back to stock, codes immediately came up. It's also quite possible you actually have a valvetronic issue. Its fairly rare but not unheard of. There's some threads on it in the N55 technical forum, which is a far better place for this than general forums.

[AlmondJayRoM3]

If you are smelling in burnt fuel then you aren’t getting proper spark. Change plugs and coil packs first. I would go back to stock heat plugs, especially if you are only sticking with stage 1.

If you want to troubleshoot the coil packs, you can do resistance checks on the primary and secondary windings using a multimeter and compare across your coil packs. You can’t do further ignition coil troubleshooting without specialized equipment.

[frchdragon]

Originally Posted by thejeremyman9

Did you uninstall bm3? There's talk that it can suppress CELs, especially for misfires. Has been reported by several people. Once they uninstalled/flashed back to stock, codes immediately came up. It's also quite possible you actually have a valvetronic issue. Its fairly rare but not unheard of. There's some threads on it in the N55 technical forum, which is a far better place for this than general forums.

This was exactly what I was checking when he said still no CEL.
I jumped to the 1st post and noticed that he had BM3.

Flash to stock and start the car, I am pretty sure that you will have a CEL...

[Randy Johnson]

Ok duly noted. Flashing back to stock today to see if I can find codes.

[Randy Johnson]

Tuned back to stock and got codes for bad coil in cylinder 6. Swapped the coil to cylinder 1 and code followed that coil. I've only got 60k miles on this car. How can coils go bad that early? Never had another car that had a bad coil even with twice as many miles. Wonder if BM3 is to blame. So I am waiting for a replacement coil to arrive.

Thank you all that suggested coils and told me to tune back to stock. With the tune I was getting valvetronic shorts which seemed a lot worse than the coil issue. Hopefully I am right.

[thejeremyman9]

Originally Posted by Randy Johnson

Tuned back to stock and got codes for bad coil in cylinder 6. Swapped the coil to cylinder 1 and code followed that coil. I've only got 60k miles on this car. How can coils go bad that early? Never had another car that had a bad coil even with twice as many miles. Wonder if BM3 is to blame. So I am waiting for a replacement coil to arrive.

Thank you all that suggested coils and told me to tune back to stock. With the tune I was getting valvetronic shorts which seemed a lot worse than the coil issue. Hopefully I am right.

You should post about this in the BM3 thread in the N55 section. A couple people suggested BM3 was suppressing codes, and your situation shows that it was not only suppressing some put also seems to mischaracterize issues and throw the "wrong code". PTF and others suggested this wasn't true, but this is yet another piece of evidence.

BM3 isnt to blame for the coil, though. 60-100k is about the range for coils, yours just happened to fall into the earlier part of the range. Could be a whole host of reasons, including the cars past life and environmental factors.

[Randy Johnson]

FCP EURO for the win!!! I've ordered my oil change kits here and they always have good prices and pretty fast shipping. Found 6 coils here and got them in about 4 days. Installed all the coils and the car is running great. I guess the coils were pretty worn out at 60k. I feel like the motor is smoother and quicker to rev even in comfort.

[hooligan_G01]

Originally Posted by Randy Johnson

Tuned back to stock and got codes for bad coil in cylinder 6. Swapped the coil to cylinder 1 and code followed that coil. I've only got 60k miles on this car. How can coils go bad that early? Never had another car that had a bad coil even with twice as many miles. Wonder if BM3 is to blame. So I am waiting for a replacement coil to arrive.

Thank you all that suggested coils and told me to tune back to stock. With the tune I was getting valvetronic shorts which seemed a lot worse than the coil issue. Hopefully I am right.

Glad you got it sorted and it turns out it was only the coils.

7 yrs/60K mi life for a coil pack doesn't seem abnormally low to me.

[jv004]

Originally Posted by thejeremyman9

You should post about this in the BM3 thread in the N55 section. A couple people suggested BM3 was suppressing codes, and your situation shows that it was not only suppressing some put also seems to mischaracterize issues and throw the "wrong code". PTF and others suggested this wasn't true, but this is yet another piece of evidence.

BM3 isnt to blame for the coil, though. 60-100k is about the range for coils, yours just happened to fall into the earlier part of the range. Could be a whole host of reasons, including the cars past life and environmental factors.

Yup.. some people were fighting tooth and nail that it wasn't true, this is the same situation I was in. Happy with my BM3 but just wanted PTF to know this was happening, if this is a bi-product of the tune then PTF should advice people to go back to stock for diagnostics rather then deny it and leave people out pulling out their hair wondering whats going on lol