P0505 code & limp mode

[Wazzock]

Evening all,

My z3 has put itself into limp mode and won’t go above 2000rpm.

Did a code read and got p0505 idle engine air control valve code, which can be numerous things apparently.

Took it to a friend at the garage who says it has a misfire on one cylinder, the spark plug and coilpack are fine. Unfortunately they didn’t have the 20pin code reader for the engine bay scan.

My question to you all is what are te most likely causes of the misfire? And what kind of cost am i looking at?

Car has done 160k miles so dontywant to be throwing good money after bad!

Cheers

 

[Jack Ratt]

Common causes of misfires are splits in the air intake rubbers or failing cam sensor. Don't be concerned about the 160k miles covered.

 

[jaguartvr]

First thing I would check is the throttle butterfly, i had one that had stuck, tap with a hammer and problem was fixed.
I also have another Z3 which will only run on tick over, it is the later version that does not have a throttle cable. I have replaced the throttle body and pedal pedometer with no success, auto electrician is booked and he seems to think it will be the ECU.
Another common problem is the camshaft sensor, I know everybody else will tell you to buy genuine but they are £120. I have had a couple from eBay for £17 that have worked perfectly and at that money not a biggie if it isn't the sensor.

 

[Wazzock]

Took the air assembly and throttle off. Turns out the valve was stuck! Bit of a clean of the throttle valve and idle air valve and running back to normal. Cheers guys