Auxiliary air device/rotary idle

[deanb34]

I took a live from my battery and tried both the terminals on the rotary idle but there was no buzz, so I ran the car and when I disconnected it the revs picked up, then when I re-connected it, the revs dropped and the car cut out. So can the rotary idle be taken apart and cleaned and oiled or does it just need replacing?

 

[Richard Moakes]

Spray WD40 into it and work the rotary part of the valve with a screwdriver from either the inlet or outlet port. They get lazy and gummed up sometimes.

Your ABS light isn't on by any chance is it?

 

[deanb34]

Thanks, no my ABS light is not on.

 

[deanb34]

I took off the rotary idle gave it some wd, and moved things about a bit but still no joy, the bit in side will move round with a screw driver and then flick back again. Is this supposed to happen? If not what is it supposed to do?

 

[Richard Moakes]

Sorry to report it's behaving exactly as it is supposed to do, it sounds like there is a problem with the electrical internals, or it isn't getting a signal from the ECU.

A 2nd hand replacement from someone like Mercman would probably be your best option.

 

[deanb34]

It does not look that old, although that does not mean anything. So is there any way of testing it once its off the car?

 

[amb67]

Sorry to report this but if you fed it 12v direct from the battery it's is more than likely scrap now. These valves are ECU controlled and usually only operate on a signal voltage of 5v.

Sounds like it may have been dead in the first place anyhow.

Try these for your replacement part http://www.mercedesparts.co.uk/

 

[deanb34]

ok thanks.

 

[television]

The correct test is to just connect it across 12v where as it should buzz, but only briefly touch it over thew 12 volt, although I am in Thialand right now I may be able to pos the ECU pin out later in the week

 

[deanb34]

I have Just re-placed the rotary idle, but its still playing up, when you start it, it will not idle unless you keep your foot on the accelerator, then if you put it in gear and go, as long as you have gone more than a mile and gone over 3000 revs it will then idle at 7 in drive and 11 in park. But if you turn it off and leave it for a few minuets you will have to do it all again to get it to idle. I think the ECU would be the next step?

 

[television]

The ECU speeds the engine up in D or with the air con is on.

The temp sensor and air temp sensor are criticle on these engines

 

[deanb34]

Hello Malcolm, do you think that something can be done with my ECU?

 

[deanb34]

Forget my last message! So which one would you look at first, and how would you test it?

 

[deanb34]

My car is now off the road until its fixed, so if you could please help me that would be very much appreciated. Many thanks DEAN

 

[deanb34]

Do you think its possible that the s/h rotary idle that I have been sent by dronsfield Mercedes could be faulty?

 

[deanb34]

I have tested the rotary idle today and it is working fine.

 

[mattkh]

I have tested the rotary idle today and it is working fine.

Hi
How about a picture of the rotary idle.

 

[deanb34]

I don’t have a photo of the rotary idle, but it has two wires, an inlet and outlet pipe. I ran a test and the idle is working when on the bench