discussion BMW X1 E84 N46 B20

[Natogamer1991]

Hi guys, looking for some insight into a problem im having.
I changed the alternator on my X1 (Automatic) about 3 months ago and from the day i changed it the cars idle is not stable. Its not a very serious surge in revvs, id say at cold start it fluctuates between 600-700rpm and at least every second it dips(you can play drums to the tune)... the car runs excellent, but as soon as its idling, hot or cold, the idle song starts .... its throwing no codes at all, and im just stumped... im thinking of putting the old alternator back on to see if it will correct itself, but i dont see how as the voltage on the new alternator is within spec... so im stumped...

 

[Mytfine]

Did you not maybe dislodge any vacuum Pipes when they did the install. Idle flucuation and no other problems has me convinced it will be vacuum related.

 

[Natogamer1991]

Did you not maybe dislodge any vacuum Pipes when they did the install. Idle flucuation and no other problems has me convinced it will be vacuum related.

That was my first thought, but iv searched high and low, i even took it to a friend who works on bmw exclusively and found nothing. He also checked the vacuum lines for leaks and found none... im stumped

 

[Mytfine]

That was my first thought, but iv searched high and low, i even took it to a friend who works on bmw exclusively and found nothing. He also checked the vacuum lines for leaks and found none... im stumped

Use a smoke machine, its easy to miss something