N54 Single Turbo Misfire — Question

kDawg08

New Member
Apr 5, 2021
4
1
0
Canada
Ride
E90 N54 ST
Intro:
Hello everyone. I recently realized that I’ve been using this forum to my benefit for awhile now and have been more then enjoying it as well as its users. With this problem at hand, I figured I might as well make an account and reach out for support & in the future maybe post my knowledge to help others.

Forum Concern:
I acknowledge there may be a chance this was spoken about and/or this is the wrong place to post my question so I would appreciate if you can guide me to the right direction/section.

Situation:
I have a 2009 BMW 335i N54 and have upgraded it to single turbo. Using JB4/mHD however don’t have a PC atm so I can’t log anything for now.
I’ve been having misfires since i got the car running when I go WOT but only when I reach high RPM 5500+
the codes were originally for Vanos and I replaced both. The codes never returned. Between the vanos codes I’ve always had cyl. 1 misfire also. The misfire code remained. Today I swapped coils from 1 to 3 and I pulled each coil out and noticed there’s a decent amount of carbon build up on top of the spark plug ( i guess in the midst of the build i didn’t torque the plugs in). Tightened them and finished swapping coils went for road test, read codes and this time had misfire 1 AND 3.
I would just like advice on where should I go now. I guess we know coil #3 will get replaced but what’s happening with cyl 1??

P.S. I feel like this might be my issue. Because my exhaust is incomplete I still haven’t welded the ports for the secondary o2’s (post cat). But put my theory away when multiple people would keep saying they run their car without them with no issues.

I realize this is a long post to read just really want to put you guys in my shoes. Appreciate any/all the help I can get and wish you all health and safety during these trying times

cheers
 
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Torgus

Major
Nov 6, 2016
1,852
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Boston
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Welcome. My guess is the plug is bad in cyl 1 and the coilpack was also bad/weak. When you swapped you saw this. Coils and plugs are cheap. I would replace both.

If money is an issue do one at a time but you will end up chasing misfires forever having both plugs and coils in various used conditions. If you have some cash, which I am guessing is the root of the issue no offense, get upgraded coils and 1 or 2 step colder NGK plugs.

You can log with a phone via MHD, almost no one uses a PC to log. I am guessing you posted this via your phone?

On a separate note I would suggest buying a laptop/pc for a variety of reasons. Much more useful than a single turbo bmw, in my opinion.

What turbo kit? What turbo? What fuel? Auto or manual? If manual, do you have a DMFW?

You need the rear 02s, but this should not be your misfire issue. It sounds like you have a number of things going on that need to be addressed.
 
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kDawg08

New Member
Apr 5, 2021
4
1
0
Canada
Ride
E90 N54 ST
Welcome. My guess is the plug is bad in cyl 1 and the coilpack was also bad/weak. When you swapped you saw this. Coils and plugs are cheap. I would replace both.

If money is an issue do one at a time but you will end up chasing misfires. If you have some cash, which I am guessing is the root of the issue no offense, get upgraded coils and 1 or 2 step colder NGK plugs.

You can log with a phone via MHD, almost no one uses a PC to log. I am guessing you posted this via your phone?

On a separate note I would suggest buying a laptop/pc for a variety of reasons. Much more useful than a single turbo car, in my opinion.

What turbo kit? What turbo? What fuel? Auto or manual? If manual, do you have a DMFW?

You need the rear 02s, but this should not be your misfire issue. It sounds like you have a number of things going on that need to be addressed.
Hello. Thanks for your reply.
I thought I gave way more info than I needed. I suppose I actually should’ve provided a bit more.
I do have a Laptop but it’s out of reach atm. You said no offence in your messages so i took none for what you said. Your assumptions, however, sort of offended me but that’s only because you don’t know my position or situation. A laptop/PC is more ‘useful’ than a turbo build. But I think most people with these car builds agree they didn’t buy/build it for its usefulness.
Now the knowledge of logging with a phone is new to me so appreciate that tip!
I am running step colder plugs new since I built the car. (Few months ago) Also running new Delphi (I believe) coils (all 6). I am hoping to upgrade the ignition system some day but wanted to make do with the factory one since I’m not looking to make any insane numbers. Just average ones.
I did not use a ‘kit’ in particular although most of my gear is VRSF, with a Tial wastegate 38mm (small) hooked up to a custom manifold. The turbo is a GT35R, 6266 with a 0.93 hot side.
My car is a manual car with a SMFW however I fail to see the correlation to the misfires. I’m running 94 Octane @ wastegate pressure of approx. 11pounds. With a Walbro fuel pump. All in all I am confident besides from the o2’s my main concern that needs to be addressed is my misfire. Even there I was hoping for a second set of eyes on the situation. If you have any advice to give I appreciate it in advance. If not, I’m already appreciative enough considering you replied to my post despite the fact that your reply was just your assumptions. I will add just for others, if they were true to someone, you would’ve probably just put thir dream down. No hard feelings
Cheers
 
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kDawg08

New Member
Apr 5, 2021
4
1
0
Canada
Ride
E90 N54 ST
Hello. Thanks for your reply. I thought I gave way more info than I needed. I suppose I actually should’ve provided a bit more. I have a Laptop but it’s out of reach atm. You said no offence in your messages so i took none for what you said. But your assumptions sort of offended me but I’ll classify them as lack of knowledge About my situation. A PC is more useful than a car. But I think most people with these cars to begin with agree they didn’t buy it for its usefulness. However, the knowledge of logging with a phone is new to me so appreciate that tip! I already am running step colder plugs already new since I built the car. Also running new Delphi (I believe) coils (all 6) I am planning on upgrading the ignition system soon but wanted to make do with the factory since I’m looking for no more then 500whp max. I did not use a ‘kit’ in particular although most of my gear is VRSF but the turbo is a GT35R 6266 with a 0.93 hit side. My car is a manual car with a SMFW however I fail to see the correlation to the misfires. I’m running 94 Octane @ wastegate pressure of approx. 11pounds. All in all I am confident besides from the o2’s my main concern that needs to be addressed is my misfire. Even there I was hoping for a second set of eyes on the situation. If you have any advice to give I appreciate it in advance. If not, I’m already appreciative enough considering you replied to my post despite the fact that your reply was just assumptions that if they were true would’ve probably just put someone’s dream down. No hard feelings
Cheers
I forgot to add, yeah I’m basically broke 🤣 not trying to spend all my cash at once. But willing to do what it takes to at least get a clean drive for now. Thanks again and looking forward to reading any suggestions !
 

Torgus

Major
Nov 6, 2016
1,852
1,307
0
Boston
Ride
ACF 6466 E92 + METH
Hello. Thanks for your reply. I thought I gave way more info than I needed. I suppose I actually should’ve provided a bit more. I have a Laptop but it’s out of reach atm. You said no offence in your messages so i took none for what you said. But your assumptions sort of offended me but I’ll classify them as lack of knowledge About my situation. A PC is more useful than a car. But I think most people with these cars to begin with agree they didn’t buy it for its usefulness. However, the knowledge of logging with a phone is new to me so appreciate that tip! I already am running step colder plugs already new since I built the car. Also running new Delphi (I believe) coils (all 6) I am planning on upgrading the ignition system soon but wanted to make do with the factory since I’m looking for no more then 500whp max. I did not use a ‘kit’ in particular although most of my gear is VRSF but the turbo is a GT35R 6266 with a 0.93 hit side. My car is a manual car with a SMFW however I fail to see the correlation to the misfires. I’m running 94 Octane @ wastegate pressure of approx. 11pounds. All in all I am confident besides from the o2’s my main concern that needs to be addressed is my misfire. Even there I was hoping for a second set of eyes on the situation. If you have any advice to give I appreciate it in advance. If not, I’m already appreciative enough considering you replied to my post despite the fact that your reply was just assumptions that if they were true would’ve probably just put someone’s dream down. No hard feelings
Cheers

Hey man, sorry if I came off as harsh.

https://mhdtuning.com/products/n54-monitor-license <-- you can also YouTube a number of videos showing you how to log, what to values log, etc via MHD. You can then upload the log to https://datazap.me/ which can be shared on the forum so we can look at your log and help analyze what is going on.

I mentioned the DMFW vs. SMFW as the DMFW is known to cause misfires above 5k under higher load than stock turbos.

How old are the coils and plugs? What are the plugs gapped to? Have you tried regapping them? 11 lbs on 93 should not throw any misfires.
 

kDawg08

New Member
Apr 5, 2021
4
1
0
Canada
Ride
E90 N54 ST
Hey man, sorry if I came off as harsh.

https://mhdtuning.com/products/n54-monitor-license <-- you can also YouTube a number of videos showing you how to log, what to values log, etc via MHD. You can then upload the log to https://datazap.me/ which can be shared on the forum so we can look at your log and help analyze what is going on.

I mentioned the DMFW vs. SMFW as the DMFW is known to cause misfires above 5k under higher load than stock turbos.

How old are the coils and plugs? What are the plugs gapped to? Have you tried regapping them? 11 lbs on 93 should not throw any misfires.
No problem my friend. I probably should’ve specified a bit more. Like I mentioned, it really is my first time using a forum. I see about the DMFW. Noted. Coils and plugs are just a year old (sitting) running they are in total 4 months old. I haven’t tried regapping them but will do it for sure to be safe. I believe I tapped them to 0.02”. I’m not sure. Do you have a recommendation for the gap space ? I agree with you that it shouldn’t. My original motor blew a head gasket due to sad complications. so this is a new motor with less mileage then my old one. But all gaskets are done and it was running fine before my car. Tomorrow I will learn mHD logging and see what I can do before disturbing the forums but will update my post with some logs from there. Thanks again ☺️
 
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