Knocking noise from Valvetronic Motor

[ariesone]

Hi all,

I seem to be having some troubles lately. I have a 323i 2006 e90. My problems all started when I noticed that on some occasions I should have idle issues. I checked the DISA valve on my intake and saw that there was not flap in place. I assumed that the previous owner removed the flap if the unit was faulty. Anyway, I purchased a second hand unit and the car seemed to run fine for a day or so. Then, I noticed that the car started to misfire and there was a knocking noise coming from the engine. The knocks increased with revs. Upon further inspection, I noticed that it was coming from the valvetronic motor.

The first thing I looked for was air leaks but could not find any. So I pulled the intake manifold off to have a better look and found the broken flap from the first disa valve. I could not find the pin however. I have changed the gaskets on the intake and the throttle body.

Another issue though... when I ran diagnostics on the new disa flap... it did not open or close so my question is, if I was running the car with the disa in a closed/blocked position, could it have caused damage or a vacuum leak somewhere. What should I look at next. Please note that I have changed the breather hoses to the oil separator..

Your input is much appreciated.

 

[Philip Foglar]

Sounds like your engine may have eaten some bits it's not suppose to! The E90post board has a large thread about the concerns of failing DISA units where the pin is ingested or the plastic flaps themselves break and become jammed in intake valves.

It is going to be a process of elimination, but I would have a compression test performed to ensure that nothing obvious was damaged internally. I would also have codes read.

 

[ariesone]

Sounds like your engine may have eaten some bits it's not suppose to! The E90post board has a large thread about the concerns of failing DISA units where the pin is ingested or the plastic flaps themselves break and become jammed in intake valves.

It is going to be a process of elimination, but I would have a compression test performed to ensure that nothing obvious was damaged internally. I would also have codes read.

Thank you for that. The code that was coming up was Variable intake system, servomotor activation (2AA8). I can only assume that this was due to the old flap causing a block. Ill do a compression test and see what the outcome is.

Thanks again

 

[Philip Foglar]

Keep us posted! I am sure they can also test the Valvetronic motor to see if there are any noises coming from it, it's usually the sensor that fails, not the motor. I never asked, what is the mileage on the car? Other things to do as general maintenance goes is to clean and swap around the Vanos solenoids, and if they are really showing signs of being dirty, you may very well have blocked Check valves in the head. These are non-return valves with fine filtering holes, and tend to get blocked up quite easily.

 

[ariesone]

Hi all, just an update... please forgive me for wrong terminology... I am not a mech but will try and explain as best as possible.

Okay, so I had a friend of mine take a look at the car and he used a borescope. Everything seemed fine however, he notice that the valve on cylinder 6 was open while all others were closed. So we removed the valve cover and basically the part that the top side of were the valve sits came apart so the valve is basically free. There doesnt seem to be damage, however, we need to put it back together to see. The plastic pin from the disa valve seems to be disintegrated. He says that when the debris was being sucked through the valve, it caused the disturbance.

I only hope the the valve isnt bent. Will know more this weekend and will update accordingly.

PS. On a side note, when we were checking the cylinders, cyl 6 had a lot of carbon where as all the other cylinders were clean. One thing I did notice when I removed the intake was that the broken disa flap was stuck in the end toward cyl 6 so that could have causing poor airflow over period.

 

[Philip Foglar]

I have seen this happen or be discussed on the E90Post forum! Happens, and hopefully the valve is not damaged. Often it's just stuck open due to the piece of plastic from the broken DISA flap that get's lodged in.

 

[ariesone]

Hi all, just an update... basically we reassembled the rocker (i think) back and the valve opens and closes properly and it seems to have done the trick. Fortunately it was not bent. The car seems to be much smoother and faster as the old broken flap was starving cylinder 6 of air and has since been removed. Thanks for the assistance all.

 

[kilotango]

phew, close call! glad you are sorted out :=):

 

[Philip Foglar]

That's a relief!!! And really glad that she is back to good health!!! :thumbs: