Fluctuating Idling RPM

[detach8]

Bros, I have a '06 E90 which I bought 2nd hand about a week ago.

When I first bought it the idle RPM was very stable. Then I let it drink herbal tea (i.e. Shell VPower) and recently when it idles it fluctuates abit.

I know in my old Nissan Latio it fluctuates too, but I've never seen it fluctuate so frequently, like 2 seconds it would be 600rpm, then 2 seconds for 700rpm, then back to 600 for 2 seconds. it's like going up and down like this every 2-3 seconds. A/C off or on doesn't stop the fluctuation.

 

[satinGHOST|r!der]

Re: Fluctuating Idling RPM

Try switching to Caltex 98 for about 2-3 tanks and see if you still have this problem. Otherwise it could be your VANOS system. Check your OBD and see if there are any errors with respect to the idling of the car.

 

[detach8]

Re: Fluctuating Idling RPM

Try switching to Caltex 98 for about 2-3 tanks and see if you still have this problem. Otherwise it could be your VANOS system. Check your OBD and see if there are any errors with respect to the idling of the car.

I poked the check button but it says "CHECK OK". I'll switch back to 98 or 95 the next tank and see if this continues. Any other bros having this problem? Or is this not a cause for worry?

 

[zorro]

Re: Fluctuating Idling RPM

I have the same problem sent to BVO to check and no fault found so I gave up.

 

[detach8]

Re: Fluctuating Idling RPM

Hmmm maybe its normal with our weather, or just a dirty MAF sensor. Ill switch fuel first.

 

[zorro]

Re: Fluctuating Idling RPM

320i got no MAF...

Hmmm maybe its normal with our weather, or just a dirty MAF sensor. Ill switch fuel first.

 

[detach8]

Re: Fluctuating Idling RPM

Huh then how does it sense? Im not familiar with bmw engines though. Thisnis coming from my ezperience with nippon cara

 

[C3P0]

Re: Fluctuating Idling RPM

detach8, you may want to bring it to a workshop to diagnose the problem (e.g. R2D). That's the best as they can give you the correct advice.....

 

[detach8]

Re: Fluctuating Idling RPM

I switched to 95 and it seems worse, but if i let my engine sit and idle for a long time (eg 15 mins) it actually stabilizes. I think its not a cause for worry but i'll get it checked at my next svc still