Rotary idle, what does it do?

[deanb34]

I only got the car a few months ago, after about two weeks it started to play up. Sometimes it would not idle when cold and when it did it was very lumpy, but more often than not it would do idle. I replaced the thermostat as it was not running very warm and I also ran some injector cleaner through it, it then idled more often but low and very up and down. I was told to test my rotary idle/auxiliary air device, so I removed it, cleaned it with carb cleaner and vary briefly gave it some volts to see if it was working, and it was, put it back on and no change. So I was told to replace it. My Mercedes parts supplier sent me a s/h one which was also clean and moved freely. Put it on and it was just the same. So I got some air intake cleaner, removed the large round disc and cleaned everything in site. Put it all back together and once it had started and burnt up all the cleaner it ran fine, idled smooth hot or cold. After a few days it went back to how it was, so when it cut out I pulled the plug off the rotary idle and it idles fine, put the plug back on and it gets rough and cuts out. With the plug off it needs to be warmed up, but once warm it idles? Any idlers

 

[jamesmc]

What car/Engine? Mileage?
Have you checked the MAF?

 

[deanb34]

its a 1991 230ce, the miles are 180059, no i have not checked the MAF,where do I find it, and how do I check it?

 

[mattkh]

My Mercedes parts supplier sent me a s/h one which was also clean and moved freely. Put it on and it was just the same.

Hi
Next time you go to the car, please take a picture of this gadget on the engine.

 

[television]

its a 1991 230ce, the miles are 180059, no i have not checked the MAF,where do I find it, and how do I check it?

http://www.detali.ru/cat/oem_mb2.as...GM=717.450&CT=M&cat=520&SID=07&SGR=030&SGN=02

this is the MAF

 

[television]

Thís is the Motronic MAF the last one was LH

 

[deanb34]

This one is already off the car so I took a photo of that, saves taking the air filter off.

 

[deanb34]

Thanks for the picture of the MAF, how do I test it?

 

[television]

Unplug it and see if it runs better and with full power though maybe a little rough

http://www.detali.ru/cat/oem_mb2.as...GM=717.450&CT=M&cat=520&SID=07&SGR=040&SGN=03

This is the link,, forgot it last time

 

[star]

All, this car hasn't got a MAF. its got bosch KE jetronic.

 

[mattkh]

This one is already off the car so I took a photo of that, saves taking the air filter off.

Hi
That was quick and really appreciated.
This gadget is what I call an idle stabilisation valve.
Normally with the ignition on, you can hear it buzzing, if everything is well.

 

[deanb34]

Thanks I will have a listen tomorrow and see, will let you know, once again thanks.

 

[star]

Have you cleaned the throtle venturi/butterfly, then check the switch is working correctly, check valve buzzes with ign on, check idle contact switch and voltage protection relay.

 

[deanb34]

Yes I have cleaned the butterfly, how do I check the idle contact switch and the voltage protection relay?

 

[deanb34]

I had a listen and no buzzing, I put a tester on the pug and there are about 8 volts. When I give the rotary idle some volts it opens a bit and just stays there but when I take the power off it shuts very fast and stops with a loud knock.

 

[television]

The switch on the side of the air flow sensor should be closed circuit when at idle and would read "no resistance" or zero

 

[television]

The over voltage protection relay has 12 volt going in on pins 30 and the output on any 87 pins should also be 12 volt,, these things often go intermittent and dry soldered connections causing a voltage drop to the engine ECU

 

[deanb34]

Sounds like we could be getting somewhere, where will I find the voltage protection relay, can it be re-soldered or should it just be replaced?