David,

Understand regarding the adjustment--L=Lean & R=Rich.

Question on another peripheral issue--for you or anyone w/insight.

Sometime back I had a problem with oscillating idle and swapped the Idle Speed Contro Unit and Idle Speed Control (Slide) Valve. After the swap, the idle went up to 750rpm, whereas it had been at 500rpm. After the swap it would also rev up from 750 to about 1200 when going into park and then settle back at 750.

Did some checking this morning and discovered I have been running a US vs Euro Idle Speed Control Unit on it. Swapped the US for a Euro I'd bought off eBay. I went back to the previous Idle Speed (slide) Valve, which my mechanic had called a "universal" one. (Cleaned it with carbr cleaner before installing.)

FYI, two or three years ago I had to replace the ISCU and the slide valve at the same time when the car would die when stopped. At that time, my mechanic installed what he called a "universal" slide valve. The difference btwn the standard valve and the 'universal' is the universal has a set/adjustment screw on the top.

I now have the Euro ISCU and this 'universal' slide valve on it and the car is idling at 500rpm. You would think I would be pleased and I am, but occasionally the idle will drop down to about 300rpm. Car doesn't falter, so I suppose it's not a problem. However, it seems there is still a glitch of some sort.

In adjusting this slide valve set screw, I presume Left is also lean and Right is rich. I'm thinking that increasing the air flow (right) thru the valve might be in order. If so, would I also make a corresponding adjustment on the 3mm tower screw on the CIS unit?

I would put this to the mechanic who installed it, but he has left the area. Wish he was still here, because the guy raced Mercedes and knew them inside out.

Thanks,

__________________
Don
'85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000
'95 C280 - 174,000