[88atlas07]

Been having this issue since I bought the car 5k miles ago. Currently at 93k miles. Idle increases from its normal 650rpm to 800ish when the oil temp reaches 160F. It never does it before hitting the magic number of 160F. Idle will not go down to normal unless car is restarted, and then it will jump back to 800rpm after a few minutes at idle.

No driveability issues, no misfires. 1 Code- Fuel pump plausability

So far have replaced:
BT cable adaptation reset/codes cleared- 100 miles ago
Ignition coils-100 miles ago
injectors (properly coded flow rates via INPA)-100 miles ago
New air filter- 100 miles ago
Pre cat O2 sensors- 1k miles ago
Intake valve cleaning (DIY using gun brushes & carb cleaner)- 3k miles ago
Spark plugs-4k miles ago

Always use 93 Octane minimum (98 super plus here in Germany), and have even tried Shells 100 V-power racing to no avail, so fuel quality is not an issue. Even did the old school tune-up of holding it at 4k rpms for 30 minutes on the highway with Chevron techron in the tank...still no difference

I have done all of the above myself thus saving quite a bit on labor charges, but even so I am over $2000 deep trying to fix this problem. I will say that the injectors were definitily going out because under full load in 6th it would hiccup and stumble a little, but never enough to throw a code, along with a hiccup/stumble at idle that has ALMOST gone away now. After the new injectors it pulls like a freight train all the way to redline with no hesitation.

Car is a 2007 Dinan Stg 3 with 93k miles, tuned since 58k. No unusual engine noises, ticks, oil consumption etc.


I have searched and read a few posts regarding misfires, and even a few concerning this 800rpm issue but didnt see any known resolutions. Anyone know of a possible fix? Next step is the hpfp and vanos solenoids after the holidays...besides that I dont know what else it could be.

[88atlas07]

Nobody has any idea what it could be?

Ordered new plugs as it still hiccups/stumbles a little at idle, maybe the ones I have in are bad eventhough they only have 4k miles on them

[Red_Bean_Bun]

What is your ride again ?

Depending on what is it - it could be a maf issue or perhaps ICV thing depending on what engine is it ....

[88atlas07]

2007 335i N54. So far I've taken the shot gun approach and replaced wear items from cheapest to most expensive hoping it would fix the issue

EDIT- Just ordered the MAP sensor as well...fingers crossed

[pits200]

You don't have the AC on, correct?

[kctim]

I'm getting the exact same thing on mine. It happened right after changing to new plugs during some preventative maintenance. Car is tuned and runs great though. I thought maybe one of the plugs got damaged during shipment, however there wasn't any noticeable damage to it. If you search for idle problems after new plugs it seems very common and these cars are quite picky.

[Monster900]

I am getting the same thing but it never happens with AC on. I did throw the code though and it showed misfire on cylinder 3 and it happed several times. I did swap the coils and misfire remained on cylinder 3. I was leaning more towards bad injector but the sparkplug sounds like an interesting idea as it did started happening about ~4k miles after sparkplugs change.

I will keep you posted as I am changing valve cover (infamies crack in cylinder 3 area) on Thanksgiving weekend and am going to look into this problem at the same time.

[Rat_House]

maybe it has something to do with the oil viscosity being lower once its warmed up?

[88atlas07]

Originally Posted by pits200

You don't have the AC on, correct?

Correct, AC is off. Havent checked with AC on, but will find out tomorrow.

I also forgot to mention that the valve cover gasket was replaced as well so the sparkplugs are dry in the plug well, so no chance of it missing due to a short.

I ordered OEM Bosch plugs and a MAP sensor that should be here in about a week, so I will put those in, reset the adaptations again via the BT cable and see if it cures anything. I will report back with what I find out. If it still does it, I will order single electrode NGK plugs that are one grade colder and see if that does anything. Single electrode plugs are rated for cars over 400hp, which im right around that mark.

It shouldnt be oil viscosity because the correct operating temp idle for the N54 is 650rpm with AC off. It has done this in low 20F weather and as high as 100F + in the summer months. Oil is fresh as well, change it every 2k miles (I know I know, overkill....but it helps me sleep at night)

Im taking the car to the Nurburgring in January (weather permitting) so want everything running perfectly before putting the car through its paces

[Gizm0]

Malfunctioning throttle body?

[88atlas07]

[QUOTE=Gizm0;14999053]Malfunctioning throttle body?[/QUOT

Maybe, any way to check the throttle body?

I did more searching and this is apparently a very common issue with the N54. After countless threads, I have not come across a remedy. Pretty sure its spark plug related but not sure if new plugs will solve it as it hasnt for many others experienceing the same issues.

Love the performance, but have never owned a more delicate car

[kctim]

[QUOTE=88atlas07;14999199]

Originally Posted by Gizm0

Malfunctioning throttle body?[/QUOT

Maybe, any way to check the throttle body?

I did more searching and this is apparently a very common issue with the N54. After countless threads, I have not come across a remedy. Pretty sure its spark plug related but not sure if new plugs will solve it as it hasnt for many others experienceing the same issues.

Love the performance, but have never owned a more delicate car

Just slap some new plugs in, much cheaper than the other route you've been going. IF you really want that buttery smooth idle back, you could always go back to the old plugs. I got bored and did that one day and it went back to buttery smooth idle but the car wasn't as strong throughout the power-band. Delicate car for sure. At least you know your car is healthy after all this preventative maintenance you've been doing

[007_e350]

I had the same issue, there's a 30 min DIY clean your VANOS with carburretor cleaner and reinsert them - Issue resolved

[kevinlevrone]

It's a "normal" issue and you can't fix it. Believe me that I tried dozens of workarounds. I had the luck of changing all injectors for free, all sparkplugs. Nothing solved it. If you clean the valves, replace injectors, replace sparkplugs, change oil, replace coils, you may get the engine not raising the idle for a month or so. And then...it reappears.

Basically when the ECU detects small "hiccups" in engine operation, it raises the idle. It may also be that it raises the idle to increase the oil speed when the engine is warm.

With the AC on the problem appears less often, because the engine runs more smoothly due to the higher idle and probably due to the AC compressor load on the engine.

I am pretty sure it's a non-fixable issue, but I am also sure that it's not even an "issue". It just means more fuel consumption at stop lights.

[88atlas07]

[QUOTE=kctim;14999872]

Originally Posted by 88atlas07

Just slap some new plugs in, much cheaper than the other route you've been going. IF you really want that buttery smooth idle back, you could always go back to the old plugs. I got bored and did that one day and it went back to buttery smooth idle but the car wasn't as strong throughout the power-band. Delicate car for sure. At least you know your car is healthy after all this preventative maintenance you've been doing

I'll give that try and hopefully that cures it. Atleast with the majority of maintence items replaced I should have many trouble free miles ahead. Knock on wood that the turbis don't go out

[88atlas07]

Originally Posted by kevinlevrone

It's a "normal" issue and you can't fix it. Believe me that I tried dozens of workarounds. I had the luck of changing all injectors for free, all sparkplugs. Nothing solved it. If you clean the valves, replace injectors, replace sparkplugs, change oil, replace coils, you may get the engine not raising the idle for a month or so. And then...it reappears.

Basically when the ECU detects small "hiccups" in engine operation, it raises the idle. It may also be that it raises the idle to increase the oil speed when the engine is warm.

With the AC on the problem appears less often, because the engine runs more smoothly due to the higher idle and probably due to the AC compressor load on the engine.

I am pretty sure it's a non-fixable issue, but I am also sure that it's not even an "issue". It just means more fuel consumption at stop lights.

Well that sucks, I've been chasing this for a while and like everyone else with the same issue have basically hit a brick wall. It may very well be normal, but it's pretty louzy from a car that cost over $40k new. I will clean the Vanos solenoids as was suggested above as Im sure it needs a cleaning anyway, and after I put in those fresh plugs I think I'm done chasing this mysterious high idle. Car runs great now otherwise and if it's not damaging and is considered normal on the n54 I guess I'll just live with it, atleast until I stumble upon some riches or win the lottery.

Thanks guys for all the feedback, very helpful