Bad idle after Vanos seals replacement

[penant78]

Hi,

I own a 2006 Z4 with the 2 liters N46.
I recently replaced the Vanos solenoids seals as It had a small leak.
Easy procedure to do, I cleaned both solenoids while they were out.

Unfortunately the car has developed a really bad idle when I drive it.
When I start it, idle is totally normal, but if I drive the car, even at, a short distance, and I stop with engine running, the idle is really bad and the engine seems to misfiring.
But if I cut the engine and restart it, even 5 seconds later, idle come back normal. And so on, cold or hot.
I'm not sure if the car has less power. If it is the case, this is minimal.

I never had any problem before so I suspect this is linked to the seals replacement, and I also read the Vanos system does not work at idle, which could explain why idle comes back to normal when I restart the car.

However, I wouldn't change the solenoids without being sure, so that would be great if some of you could give more information, maybe it already happened to you.

 

[Jfgoldfish]

I am subbing to this.
My zed has a fairly rough idle that is suspect has something to do with the vanos system.

 

[ph001]

Well if the problem coincided with the cleaning of the solenoids I think I'd struggle to convince myself to do anything else before I'd replaced them both for what they cost.

 

[NickDE]

You didn't get the wires switched between the two whilst reassembling ? Just a thought.

Otherwise get the error codes read and see what comes up.

 

[Jfgoldfish]

Could someone please post a pic to confirm the connector placement?
I assume the top one goes to the upper solenoid and visa versa.

 

[Rucky]

When I changed mine out this happened - just a thought.
(Cant send a pic - the wifes away in it.)
Incidentally found an interesting fault that caused very rough running, poor idle and multiple faults related to Mass airflow.

"When I refitted the Plastic Cam cover I didn't seat the square Oil fillet cap properly - first engine start was worse that before I changed the solenoids - idle hunting and very rough.

This BMW engine needs a well sealed cam cover/ oil filler otherwise it upsets the pressure differential across the mass flowmeter!!!!"