Last year I took my car into the dealer with a rough idle. They said that the injectors were dirty and weren't allowing enough fuel to get into the cylinders at idle, so what they did is they cranked up my CO setting so "more fuel could get into the motor at idle" and supposedly cure my problem. Well after being a regular visitor to this forum for a few months now, I have seen the rough idle issue come up quite a bit and never once have I heard of someone else doing this or recommending this. So I am thinkin the dealer was full of it. By the way, my rough idle did not get better, actually worse at times...AND I obviously get worse gas mileage.

So my questions: how can I figure out or does anyone know what my CO was set to from the factory (euro car, so it might be different?), can I do this myself? and where is the dial? Thanks for any help!

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."

I'm not takin it back there! Where is the screw? I think they mentioned something about some seal over it or something that shouldn't be broken unless it's authorized or something...??

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."

Well, if the plug is intact then they didn't change the setting. The adjustment screw is accessed through the small hole in the air cleaner, takes a long 3mm allen, but the plug has to have been removed from the tower. Yes you should have an exhaust analyser to adjust, but one flat counter clockwise will lean it out a bit. Adjustments have to be made with the engine running.

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Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Thanks guys! Mike, do you think you could describe a little more in detail what I should be looking for in reference to this plug and it being intact? And the little hole...is it inside the air cleaner? Is it easy to find?

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."

Easy to find? Well, it is the only hole in the top of the air cleaner . That hole allows adjustments to be made with the sytem properly closed.

If you remove your air cleaner you will see the tower, it is between the fuel distributor and the throttle body. If you cannot insert a long allen (or suitable probe) into the end of the tower, then it is plugged (should go in about 1.5-2 inches if unplugged). Two types of plugs have been used, one a small cylinder, the other a ball bearing. According to the manual, the plug is drilled out for corrective adjustmeents, then a new plug is inserted. In most cases, if an adjustment has been made the plug is not replaced.The hole in the air cleaner is accurate for US models, not sure if Euros are set up the same.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.