E90 325i 2006 rough idle

[nick7]

New to the forum and would really appreciate some advice please. Engine runs rough when stationary (almost as if it is missing and body shakes). If I cut ignition and restart, engine runs normally but will idle roughly when stationary again. The vanos intake adjuster has been replaced 3 times (yes 3!) but problem eventually re-appears. Vanos solenoids are checked each time problem re-appears and are fine. Does anyone have any ideas as to what I am missing? Thanks!

 

[husaindindar]

Hi, welcome.

N52 has it's fair share of issues with vanos, disa, valvetronic motors, coils etc.

Best is to have the codes read. That way it's easier to pin the issue down.

From my experience, solenoids cannot be checked, but rather replaced. But lets get codes first.

 

[Coisman]

Sounds like it might be a dirty Idle Control Valve, my E46 325i did that, the idle would also sometimes jump up to 1500rpm and back down, with a rough idle.

 

[Solo Man]

This is a common problem on the valvetronic motors. It sounds like an air leak. Could be the tappet cover packing leaking, or even the oil filler cap. Search on this forum and you will find quite a few people having the same problem seeking answers. Hope you come right! My money is on an air leak as i said, seeing you have already replaced the vanos adjuster as well as checked the solenoids. Did some one perhaps change the tappet cover packing before all your problems started? I have two used solenoids here in my garage which i am certain is fully functional as i have replaced them with new ones but the new ones did not solve the problem.

 

[Mohammad]

It would be best to have the codes read. I had a similar issue and it was the O2 sensor that was bad.

 

[nick7]

Thanks, I will het the codes.

 

[nick7]

Thank you for the replies. The code is for vanos intake adjuster (again!). Any ideas as to what could be causing the fault each time?

 

[CA_130]

Sounds like a bad O2 sensor, when the car starts up at first it will ignore the O2 until it gets to temp, once "there", it will make use if the reading(s) again. If the O2 is busted it will send shoddy values to the ECU causing it to rough idle.

If you then switch it off and on again, it will most likely do the same thing repeatedly, start up great and then start crashing.

Have the codes read, or look at the live values of the O2 on one or both banks.

 

[nick7]

Sounds like a bad O2 sensor, when the car starts up at first it will ignore the O2 until it gets to temp, once "there", it will make use if the reading(s) again. If the O2 is busted it will send shoddy values to the ECU causing it to rough idle.

If you then switch it off and on again, it will most likely do the same thing repeatedly, start up great and then start crashing.

Have the codes read, or look at the live values of the O2 on one or both banks.

Thanks for the reply. I had the codes read. The first was for Bono’s intake adjuster - low oil level. This appears to have been remedied by topping up the oil ( oil level sensor read ‘“Inactive” but fault was rectified). After further test drive, or came up with Code 2AAB - DME: Variable intake system, self diagnosis (code not currently present).

Does anyone have any ideas? Would it be necessary to have a look at DISA or wait until fault presents itself again? Also, any ideas why the vanos intake adjuster fault is so prevalent on my vehicle (3 times in 2 years with 2 new vanos intake adjusters). Would appreciate all comments and suggestions.

 

[nick7]

Sounds like a bad O2 sensor, when the car starts up at first it will ignore the O2 until it gets to temp, once "there", it will make use if the reading(s) again. If the O2 is busted it will send shoddy values to the ECU causing it to rough idle.

If you then switch it off and on again, it will most likely do the same thing repeatedly, start up great and then start crashing.

Have the codes read, or look at the live values of the O2 on one or both banks.

Thanks for the reply. I had the codes read. The first was for vanos intake adjuster - low oil level. This appears to have been remedied by topping up the oil ( oil level sensor read ‘“Inactive” but fault was rectified). After further test drive, it came up with Code 2AAB - DME: Variable intake system, self diagnosis (code not currently present).

Does anyone have any ideas? Would it be necessary to have a look at DISA or wait until fault presents itself again? Also, any ideas why the vanos intake adjuster fault is so prevalent on my vehicle (3 times in 2 years with 2 new vanos intake adjusters). Would appreciate all comments and suggestions.

 

[Sabre]

Sounds like a bad O2 sensor, when the car starts up at first it will ignore the O2 until it gets to temp, once "there", it will make use if the reading(s) again. If the O2 is busted it will send shoddy values to the ECU causing it to rough idle.

If you then switch it off and on again, it will most likely do the same thing repeatedly, start up great and then start crashing.

Have the codes read, or look at the live values of the O2 on one or both banks.

Thanks for the reply. I had the codes read. The first was for Bono’s intake adjuster - low oil level. This appears to have been remedied by topping up the oil ( oil level sensor read ‘“Inactive” but fault was rectified). After further test drive, or came up with Code 2AAB - DME: Variable intake system, self diagnosis (code not currently present).

Does anyone have any ideas? Would it be necessary to have a look at DISA or wait until fault presents itself again? Also, any ideas why the vanos intake adjuster fault is so prevalent on my vehicle (3 times in 2 years with 2 new vanos intake adjusters). Would appreciate all comments and suggestions.

I had the same code 2AAB, the larger DISA valve’s flap was loose. They can break loose and cause damage to the engine.

 

[Sabre]

That being said, I didn’t experience any rough idle with the broken disa flap.