schmick325

Sorry, I mean Purge valve!

My w164 ML63 has been idling a bit rough, especially when warm.

Checked all hoses and thought I had it when I found a small vacuum hose at the back end of the motor loose. 1 hr later when it was warm it was still doing it.

Had a look on here for common issues and I ended up running the car with the Purge Valve harness disconnected. Wow what a difference. Idle is smooth as.

I toured around for about 30 mins, pulling over to connect and disconnect it.

It definetly has to be the culprit.

Has anyone else changed out one of these?

Does seem strange that the car works great with it disconnected!

No engine lights at all either, connected or disconnected.

schmick325

engine light now on, most likely due to me driving around with the harness disconnected.

Still runs miles better though. Buying one on Monday.

rfarrell44

sounds right have u had any issues with head gaskets leaking oil?

schmick325

Dont think its PCV valve anymore, car is now idling higher than normal and using more fuel than normal.

Off idle its still a beast and has no hesitations pulling to red line.

Its definetly something to so with intake / emissions systems on the car.

No oil leaks or coolant loss or anything like that.

Going into the shop tomorrow and hopefully they find the culprit.

The exhaust is so deep at idle it's resonating in my ears!

newguy2008

Hi, can you update us on what caused the issue?
Thanks.

schmick325

There is an adjustable 'runner' in the intake that adjusts depending on load and revs and this was gummed up and jammed, not allowing smooth operation and the required amount of air going into the cylinders.

newguy2008

Thanks and appreciate the quick reply. So you had to have the intake manifold taken off (the middle silver piece in the pic) and cleaned or did the runner part have to be replaced? How much approx. was the repair?

Thanks again.

aden

Hi I have a 2009 ml320 and trying to locat the purge valve. Is any one familiar with the location of that valve, can I access from the top in the engine compartment or need to go from bottom of the car? If there is a picture that will really help a lot. Thanks!!