[Jack Bell]

I have been running a stage 1 93 octane tune on my 550i (n63tu engine) for about maybe 3 weeks and all has been perfect, from acceleration to shifting and of course more power. everything up till earlier today has been completely smooth and working as it should. today after warming the car to running temp and driving about 15 miles i felt some power loss on the high way. a kind of oscillating feeling in the power and then, boom, limp mode. i pulled off highway immediately into a parking lot and of course heard the misfire “pops”. checked codes and got the image i attached. not sure why it happened and i’m hoping someone can help me out. flashed back to stock tune and the rest of the day it was fine. would really like to figure this out though because i enjoy my extra hp

[Houranimd49]

As the codes suggest, there’s misfiring. Any time we increase power in any car, we are pushing the engine and its components that much harder. Typically it’s suggested that we complete routine maintenance (such as brand new plugs and coils) before upgrading for more power. Not saying you didn’t already do that. But I would start at changing your plugs.

If you’re looking to only diagnose first, swap them around from problematic cylinder to good cylinder (I.e cyl 6 which is misfiring to cyl 1.) if cyl 1 is now misfiring and cyl 6 isn’t, you can make a diagnosis of that particular spark plug is bad. But honestly, since you’re already in there, I’d just change them.

Bimmerlink has an option where you can select to see which cylinder is actually misfiring and how many counts as well.

[Hoa]

A failing HPFP tend to cause multiple cylinder misfire. It is rare for more than one spark plug, coil pack or injector to fail at once.

[Jack Bell]

Originally Posted by Houranimd49

As the codes suggest, there’s misfiring. Any time we increase power in any car, we are pushing the engine and its components that much harder. Typically it’s suggested that we complete routine maintenance (such as brand new plugs and coils) before upgrading for more power. Not saying you didn’t already do that. But I would start at changing your plugs.

If you’re looking to only diagnose first, swap them around from problematic cylinder to good cylinder (I.e cyl 6 which is misfiring to cyl 1.) if cyl 1 is now misfiring and cyl 6 isn’t, you can make a diagnosis of that particular spark plug is bad. But honestly, since you’re already in there, I’d just change them.

Bimmerlink has an option where you can select to see which cylinder is actually misfiring and how many counts as well.

I’m new to bmws and cars in general and haven’t changed the spark plugs or coils. just went out and bought some nkg spark plugs going to throw them in tomorrow and hopefully will see improvement

[Jack Bell]

Originally Posted by Hoa

A failing HPFP tend to cause multiple cylinder misfire. It is rare for more than one spark plug, coil pack or injector to fail at once.

what is “HPFP”? i’m new to all of this

[Hoa]

Originally Posted by Jack Bell

what is “HPFP”? i’m new to all of this

High pressure fuel pump

[Houranimd49]

Originally Posted by Jack Bell

I’m new to bmws and cars in general and haven’t changed the spark plugs or coils. just went out and bought some nkg spark plugs going to throw them in tomorrow and hopefully will see improvement

The high pressure fuel pump is a possible candidate but you’d notice other symptoms in addition to misfiring. Maybe someone else can chime in about the reputation of the HPFP with regard to the n63tu…. (More popular with n54/n55).

I think swapping spark plugs is a good step, they probably need to be changed anyways. Welcome to BMW, where maintenance means more than any other brand 😅 pay to play. Keep us posted please.

Edit: I reread the original post and realized you said that the car was fine after you went back to the stock tune. I had this issue before with the n55 on a little JB+ tuner and it actually came down to having to change the plugs for me. Either way, I’m interested to know your outcome!

[Jack Bell]

just an update for y’all

busted open the 550 today to change spark plugs and i don’t have the right plug socket…

ordered a thin wall 14mm (because bmw has their own special socket) and should have plugs installed in a day or two (maybe more if i get busy with school) but i’m looking forward to giving y’all some good news once the ngk plugs are in!

[Houranimd49]

Oh man, I should’ve told you about the thin walls socket. Best of luck and still would love to stay in the loop about this.

[Double Nickel]

Just a thought, but did you get colder plugs? Tune and timing. Idk im new to this too

[Jack Bell]

Originally Posted by Double Nickel

Just a thought, but did you get colder plugs? Tune and timing. Idk im new to this too

I do believe that the NGK spark plugs that I got are a colder plug. I’m not sure off the top of my head with the difference is. And yes, for the stage one tune, I’m running there is a recommended gap to step on the spark plug, and for that I ordered a spark, plug, gapping tool, and the thin measurement tool. From what I’ve read when you’re running a tune, you’re better off, making the gap smaller so that there’s a less likely chance of misfiring. If you’re looking to get your own spark plugs, I would read up on which ones are good for your engine and for the tune that you’re wanting to run on it, don’t be like me, definitely read up about what you wanna do to your car and what you need when you’re going to do it.

[Jack Bell]

last update for now.

got the new plugs in yesterday and it runs extremely well. i also took a look at the fuel pump and the fuel lines for any problems. i saw that where the fuel pump line feeds into the intake area it was a little loose. i smacked it back into place and nothing has been weird since.

took a while to figure out everything i needed and how to gap according to my tune. overall it was fairly simple and the misfire problem is fixed for now.

thanks to everyone who helped me diagnose and helped me with the steps!

[Houranimd49]

Originally Posted by Jack Bell

last update for now.

got the new plugs in yesterday and it runs extremely well. i also took a look at the fuel pump and the fuel lines for any problems. i saw that where the fuel pump line feeds into the intake area it was a little loose. i smacked it back into place and nothing has been weird since.

took a while to figure out everything i needed and how to gap according to my tune. overall it was fairly simple and the misfire problem is fixed for now.

thanks to everyone who helped me diagnose and helped me with the steps!

Glad to hear things have worked out. How does it run with the tune back on?

[Jack Bell]

Originally Posted by Houranimd49

Glad to hear things have worked out. How does it run with the tune back on?

With the tune back on its running amazing and now that it’s back to normal i’m considering a transmission flash. before I changed the plugs it wasn’t running nearly as well as it is now and it’s a bit to quick for the stock transmission tune. Do you happen to know anything about the xhp flash for transmission? i’m not sure which stage to use because i’m thinking of going stage 2 on bootmod3 soon.

[Houranimd49]

Originally Posted by Jack Bell

With the tune back on its running amazing and now that it’s back to normal i’m considering a transmission flash. before I changed the plugs it wasn’t running nearly as well as it is now and it’s a bit to quick for the stock transmission tune. Do you happen to know anything about the xhp flash for transmission? i’m not sure which stage to use because i’m thinking of going stage 2 on bootmod3 soon.

Awesome! Anything I know about the xhp trans flash came form the forums which you can find pretty easily. My F10 didn’t come with the sport auto transmission so it’s something I’ve been wanting to do for quite a while.

With the transmission flash combined with engine tuning on the n63tu, you’re looking at a pretty stupid fast car. I’m jealous lol!

[TuckerE36]

Originally Posted by Jack Bell

With the tune back on its running amazing and now that it’s back to normal i’m considering a transmission flash. before I changed the plugs it wasn’t running nearly as well as it is now and it’s a bit to quick for the stock transmission tune. Do you happen to know anything about the xhp flash for transmission? i’m not sure which stage to use because i’m thinking of going stage 2 on bootmod3 soon.

I have a custom tune and stage 2 xHP, they work great together. I wanted stage 2 because it was in the middle. Two things that are important with xHP at least to me, in manual mode it will NOT automatically shift at the rev limiter, you have to shift or you’ll just bounce, secondly the tune puts the highest possible gear while city driving in comfort. So, going 40 mpg I’m in 8th gear and at 1,100ish rpm. All this to say keep and eye on our oil temps it will take longer for your oil to come to temp.

When the transmission is in sport and engine in Sport + it slams through gears, lotta fun. Fun using launch mode too.