[David_Vasha]

Hey everyone. I tried everything I feel like and I still don't u der stand why my N55 is running rough while idling. I decided to take my car to a dealership for diagnostic. I currently have MHD installed as well. Should I flash it back to stock before having the car go there?

[ziekxq]

What you mean by running rough? Idle, while driving?

[David_Vasha]

Originally Posted by ziekxq

What you mean by running rough? Idle, while driving?

While idling

[S1nner]

I would assume you've scanned the car already and if there is no any error codes I'm not seeing any reason going to the dealer. You'll hear something like where do you put gas? Costco? Oh Costco is not good, so let's clean fuel system. Will it help, we don't know. etc etc. I still have a very tiny vibration while idling and I've been at the dealer, who couldn't say anything except that my fuel system needs to be cleaned. Just my 2 cents.

[David_Vasha]

Originally Posted by subkg

I would assume you've scanned the car already and if there is no any error codes I'm not seeing any reason going to the dealer. You'll hear something like where do you put gas? Costco? Oh Costco is not good, so let's clean fuel system. Will it help, we don't know. etc etc. I still have a very tiny vibration while idling and I've been at the dealer, who couldn't say anything except that my fuel system needs to be cleaned. Just my 2 cents.

For what it's worth. They have better equipment than I do to figure out this problem. My idle doesn't just have vibrations but sometimes it stumbles too when it's bad. I've gotten misfire codes before but they don't explain why

[ziekxq]

Have you tried replacing pully belt aka serpentine belt?

[Jcole9656]

Originally Posted by ziekxq

Have you tried replacing pully belt aka serpentine belt?

Fuel injectors need replacement or cleaning? My buddy is a mechanic and he assured me that those are common item past 50,000miles

[ziekxq]

Originally Posted by Jcole9656

Fuel injectors need replacement or cleaning? My buddy is a mechanic and he assured me that those are common item past 50,000miles

I am at 118k and still no issue with fuel injectors... Though I have been on Shell 93 oct ever since I got the car... Just providing data... He might be on good fuel too. My buddy is a BMW master mechanic and haven't said anything about that.

[OnlyGerman]

Originally Posted by Jcole9656

Fuel injectors need replacement or cleaning? My buddy is a mechanic and he assured me that those are common item past 50,000miles

Your friend has bad info lol.

[David_Vasha]

Originally Posted by ziekxq

Have you tried replacing pully belt aka serpentine belt?

Yes I replaced the belt tensioner and a faulty low pressure fuel sensor. I also went ahead and changed the oil today. Gonna drive the car tomorrow and hope it cures anything.

[burro_blasta]

I've read that old/bad coils are a common cause of idle issues. If you're at 118k miles and if you're due for plugs and coils then that definitely needs to be done before you do anything else (including taking it to the dealer)

[HotSpicyChicken90]

Originally Posted by David_Vasha

Hey everyone. I tried everything I feel like and I still don't u der stand why my N55 is running rough while idling. I decided to take my car to a dealership for diagnostic. I currently have MHD installed as well. Should I flash it back to stock before having the car go there?

can you be more specific?

[David_Vasha]

Originally Posted by HotSpicyChicken90

can you be more specific?

Car stumbles when idling sometimes. Could be a multitude of things. No codes have popped up on th DME

[David_Vasha]

Just changed the oil and the idle has gotten significantly better. I'm starting to think that it could be Vanos if it is oil related. I can still feel it acting up though.

[Force2013]

i'm in the same boat as you..
My car shakes on idle and i have done a everything i can think of. i have changed Coils, sparkplugs, injector, checked the engine mounts oil change.
I have done a rough running control with ista+ and all other checks "no codes"

it's driving me nuts i can tell you that.

[David_Vasha]

Originally Posted by Force2013

i'm in the same boat as you..
My car shakes on idle and i have done a everything i can think of. i have changed Coils, sparkplugs, injector, checked the engine mounts oil change.
I have done a rough running control with ista+ and all other checks "no codes"

it's driving me nuts i can tell you that.

It's been driving my ass nuts too. That's why I'm taking my tune off the car and taking it to the dealership for their diagnostic team to handle. It's only like $140 which isn't that bad price wise.

[Trainwreck914]

I don't have rough idle. But it does feel like a slight miss and stumble occasionally at idle. When I say occasionally I mean every few revolutions. It's consistent. Not driving me nuts. And I'm not throwing parts trying to solve it. I have done spark plugs almost a year ago. Have not done vanos, coils, injectors, or motor mounts. Constantly read from members that there are a lot of f10/n55 with the same symptoms. And no error codes. BMW will tell you it's "normal". Or atleast that's what others report back. Hope you find a solution. I'd like to know what's the "fix". Not sure but just throwing this out there. But maybe walnut blasting may help. I plan on getting that done sometime in the near future anyway.

[David_Vasha]

Originally Posted by Trainwreck914

I don't have rough idle. But it does feel like a slight miss and stumble occasionally at idle. When I say occasionally I mean every few revolutions. It's consistent. Not driving me nuts. And I'm not throwing parts trying to solve it. I have done spark plugs almost a year ago. Have not done vanos, coils, injectors, or motor mounts. Constantly read from members that there are a lot of f10/n55 with the same symptoms. And no error codes. BMW will tell you it's "normal". Or atleast that's what others report back. Hope you find a solution. I'd like to know what's the "fix". Not sure but just throwing this out there. But maybe walnut blasting may help. I plan on getting that done sometime in the near future anyway.

I thought that walnut blasting wasn't necessary on n55s since our ventilation systems were a lot better than the previous gen n54 which had caused their significant amount of carbon buildup.

[Trainwreck914]

I took my intake off to do my starter about a year ago. And there was carbon build up on the valves. Let me see if I still have those pics.

Yup. Here you go. Kinda hard to see in the pics. Had the flash on the iPhone.

[ThaiBruin]

Definitely flash back to stock if you decide to take it in. I have Bootmod3 and I've flashed back to stock the two times I've taken my car in for service (under warranty).

[ezaircon4jc]

Originally Posted by David_Vasha

Car stumbles when idling sometimes. Could be a multitude of things. No codes have popped up on th DME

I don't know how BMW does it, but on my last car (American manufacturer) a dirty/failing idle air controller would cause a surging idle. Before Costco went TopTier their gas would cause a slightly rough idle (I also "lost" about 75 miles per tank); since they went to the TopTier the rough idle cleared-up (again, my last car).

[Force2013]

Originally Posted by ThaiBruin

Definitely flash back to stock if you decide to take it in. I have Bootmod3 and I've flashed back to stock the two times I've taken my car in for service (under warranty).

Well if you figure it out please share it with me and will buy you a beer!