420SEL ICV removal:
 

Hello All, after cleaning the throttle body in my 89 420sel.. it has developed a High idle symptom.. after some research was determined that the ICV should most likely be cleaned.. The two hoses connected to the ICV are very hard and brittle.. so before removing I went ahead and ordered brand new hoses... is there any other procedure I should be aware of in the removal of the ICV other than the connector, 1 screw/clap and connection to the 2 hoses? From other threads I have done some homework on cleaning the ICV, but in case anyone has anything to add It would be much appreciated... Thanks all so much in advance!!

Ok so Reg stopped by today and we looked at the IACV....I did the 9v battery thing, heard a click...we checked resistance of the valve five ohms...we have five volts with the engine running and ZERO instead of 12 with key on ...that made little sense to me but it's what the multimeter said....

From what I've read it could be the control unit...I dont know enough about the gassers to get into it. I told Reg we needed to research and referred him to a great local indie who knows the cars really well.

I was thinking what we should do, as I have done on other cars before...is remove the valve and clean it. The high idle started when we were squirting intake cleaner at the throttle body while running the engine right before an oil change. There has got to be some carbon knocked loose and chunked up on the valve right?

Well without knowing the process for removal and reinstallation of the valve...I didnt want to try. Reg has new "boots" for it...still...I told him we need to research this some more.

If anyone has suggestions on diagnosis and or can point me to the RnR procedure for that valve...much obliged.

How high is the idle? My 420 likes to idle around 1000-1200 in park, but 600-700 in drive....if I unplug the idle valve it goes much higher (1600-1700 or so)

Idle was normal around 650-700rpm... After foaming the throttle body car now idles between 1200-1500rpm in park... Normal idle in drive :confused: