[HunterW335]

Hey All, first post on here.

I recently just bought this 2007 335i with 43k miles a few months ago and so far everything has been great! I've swapped the charge pipe, intake, and downpipes with all VRSF parts and decided to swap out the spark plugs and coils as well.
I changed the stock plugs and coils out with NGK plugs and Coil I found on amazon. The first few days seemed fine, until I came out of work one afternoon and fired her up on low gas, it was rough and my RPMS staggered for about a minute till the SES came on. Kinda seemed like it was making a (pop pop pop) sound constantly while it was running idle now. Checked codes and gave me: 29CC 29D0 29D1 29D2
Drove slowly to closest gas station filled up, and started again... and everything seemed fine. Next day go to start early in the morning for work, Misfires happen again... I've parked it and barely have driven it since.

I was told that the cause could be the injectors? or maybe the HPFP? maybe the coils are just duds?
First BMW and any help or info of what it could possibly be would be greatly appreciated! Thanks!

[Dave92N54]

What NGK plug #? What gap did you set? What coil brand? These cars do not take kindly to off brand coils AT ALL. A bad coil can lead to a mosfet shortage on MSD80 cars, which you have.

[BSM n54iS]

Ya hold on which NGK plugs did you purchase? Are you tuned stage 2+ also with mods, if not you really have no need for NGK plugs, and even then you have to make sure you gap them TO THE thousandths of an inch. Up to you if you want to keep them or try switching to oem Bosch and go from there

[HunterW335]

The NGK plugs are #97506, I switched to them because I planned to go stage 2+ I just hadn’t tuned myself to 2+ yet. I’m guessing swap out the coils for some actual OEM ones and the NGK plugs should be ok? Or will the NGK plugs have to go as well?

[Bimmer_Bro]

[QUOTE=HunterW335;29630808]The NGK plugs are #97506, I switched to them because I planned to go stage 2+ I just hadn’t tuned myself to 2+ yet. I’m guessing swap out the coils for some actual OEM ones and the NGK plugs should be ok? Or will the NGK plugs have to go as well?

NGK plugs are not needed for any MHD tunes. This is the biggest miss understanding with these cars. Colder plugs are also not needed with off the shelf tunes unless you are chasing a problem or having large timing corrections.

Bosche 3 prong oem plugs handle stage 2+ with no problem and no gapping needed. I have used these for over 5 years without a issue.
For coil packs use bosche, or Delphi or Eldor. Those are all very popular and work well.

[BSM n54iS]

Originally Posted by HunterW335

The NGK plugs are #97506, I switched to them because I planned to go stage 2+ I just hadn’t tuned myself to 2+ yet. I’m guessing swap out the coils for some actual OEM ones and the NGK plugs should be ok? Or will the NGK plugs have to go as well?

Then yes definitely go back to oem plugs & coils until you tune. Then from there change if necessary but it's not necessary really until upgraded turbos you'll find

[Dave92N54]

Gap the 97506s appropriately. I cannot remember the gap for them as I use 97968s which are one step warmer.

Then yes, OEM coils. I would recommend Delphi or Eldor.

[HunterW335]

Originally Posted by BSM n54iS

Then yes definitely go back to oem plugs & coils until you tune. Then from there change if necessary but it's not necessary really until upgraded turbos you'll find

So I swapped the NGK plugs and new coils out back for both my stock plugs and coils, and I’m still getting rough cold start with misfires and flashing SES…
I have new Delphi coils coming and can get new spark plugs as well but I just don’t know what else it could be after changing it back out to stock.
Whenever I start it and it misfires it gives off a heavy gas smell but I figured that was just from my downpipes being catless.

[Bimmer_Bro]

Park the car overnight. Without starting it, pull the plugs and see if they are wet with fuel. This would point to leaking injectors

[HunterW335]

Originally Posted by Bimmer_Bro

Park the car overnight. Without starting it, pull the plugs and see if they are wet with fuel. This would point to leaking injectors

When I pulled out the NGK plugs today from the car sitting a few days, they didn’t seem wet or coated. Cylinder 1 plug seemed pretty black though for being decently new.
Here’s a photo, just in case. they seem ok to me?

[Bimmer_Bro]

Ya they look ok. Maybe your new incoming coils will solve the issue. Either way stick with the bosche 3 prong even when tuned.

There is an option in MHD called cold start noise reduction. This eliminates the warming cat procedure on a cold start. Some people have turned this on and it's eliminated their cold start missfires . Just an idea.

[BSM n54iS]

If you didn't smell any fuel on them then next step would be logging your cold start with MHD, chances are you will see your hpfp or lpfp pressures off somewhere

[HunterW335]

I feel stupid not looking more into it till now but, I’ve also been throwing a 2C24 code (Oxygen sensors before catalytic converter: swapped) this had been showing up since I installed the downpipes and plugs/coils. Could this O2 sensor possibly be the leading cause?

[Bimmer_Bro]

Originally Posted by HunterW335

I feel stupid not looking more into it till now but, I’ve also been throwing a 2C24 code (Oxygen sensors before catalytic converter: swapped) this had been showing up since I installed the downpipes and plugs/coils. Could this O2 sensor possibly be the leading cause?

Did they get mixed up during install ? You sure there is no exhaust leak around the downpipes Also?

[HunterW335]

Originally Posted by Bimmer_Bro

Did they get mixed up during install ? You sure there is no exhaust leak around the downpipes Also?

I’m not sure if they got mixed up during install as I had an indie mechanic do the install since I didn’t have the time on my hands currently, so now thats leading me to think that could be something he didn’t connect right…

[Bimmer_Bro]

Originally Posted by HunterW335

I’m not sure if they got mixed up during install as I had an indie mechanic do the install since I didn’t have the time on my hands currently, so now thats leading me to think that could be something he didn’t connect right…

It's a common error they get swapped. It will make the car shake and missfire like crazy. If it drove normal for a while then I doubt that's it.
You might be able to swap the connectors and see if it makes it better or worse.

[HunterW335]

Originally Posted by Bimmer_Bro

It's a common error they get swapped. It will make the car shake and missfire like crazy. If it drove normal for a while then I doubt that's it.
You might be able to swap the connectors and see if it makes it better or worse.

I’ll see if I’m able to get underneath and swap them tomorrow, or I’ll bring it by an indie and see if they can swap them really quick for me. When the downpipes we’re first put on, there had always been a shake from under the cabin, dude that put them on said it would be normal for it to shake. It has a crazy shake and start up now with the misfires so hopefully this will fix it. Fingers crossed

[Bimmer_Bro]

Originally Posted by HunterW335

I’ll see if I’m able to get underneath and swap them tomorrow, or I’ll bring it by an indie and see if they can swap them really quick for me. When the downpipes we’re first put on, there had always been a shake from under the cabin, dude that put them on said it would be normal for it to shake. It has a crazy shake and start up now with the misfires so hopefully this will fix it. Fingers crossed

Good luck. Definitely should not shake or rattle on anything. Hopefully that's the fix.

[AWD Addict]

Originally Posted by Bimmer_Bro

Ya they look ok. Maybe your new incoming coils will solve the issue. Either way stick with the bosche 3 prong even when tuned.

There is an option in MHD called cold start noise reduction. This eliminates the warming cat procedure on a cold start. Some people have turned this on and it's eliminated their cold start missfires . Just an idea.

I had this issue with the MHD tune, and turning off that setting fixed my rough idle at start.

Otherwise, based on the above discussion, I'm leaning injectors.

I also think your cyl1 plug looks pretty rough for being new. I bet that's the location of your issue. I disagree with the above poster that the issue with an injector would only present with throttle open. I had a bad injector shaking my car at idle multiple times since I've bought it (15 years on now.)

[Fbo_n54sfv]

Cylinder 1 injector for sure leaking and spraying fuel on spark plug

[whyzee125]

It shouldn't shake because of downpipes--if that's when the issues started, it sounds like the O2 sensors got mixed up. It should run exactly like stock with downpipes, just a LITTLE louder. Those plugs don't look wet but I'm not exactly sure what black means--likely the mixture is off, though I'm not sure why just on one cylinder.

What index are your injectors? Good move on the new Delphi coils, off brand ones aren't reliable at all.