89 260e idle/acceleration problem

[Tom 260E]

I'm having problems with my 1989 260e with intermittent rough idle and intermittent poor acceleration. I was getting on the freeway yesterday and pushed on the gas only to have the car stumble all over itself. I was gaining speed soooo slowly it was scary; it shifted very hard at about 40mph and then things began to pick up. Idle is rough occasionally even when eng is warm. I've owned the car about a year now and have done alot of work to it . It only has 61k miles on it now andhad only 44k on it when I bought it last August from the original owner. I have found out that even with low miles, time is an enemy as well. I have replaced many parts because they were original and the following are some parts that are often associated with my current problem: spark plugs (H9dc), wires (beru), cap and rotor, injectors, all filters including fuel, fuel accum (hard starts), EHA valve (leaking), and valve stem seals. The EHA and fuel accum were done at at a local independent MB shop. Following that visit I got a "check eng" light. The led flashed 8 x's which means the altitude compensator. I'm told that part rarely fails but I replaced it with one from a local bone yard and still get the light. I have not replaced the OVP relay although I checked the fuse and it's not blown; or the O2 sensor. A MB tech told me that code 8 can also be due to lean mixture and not just the alt compensator. Any help would be greatly appreciated

[psfred]

Tom:

I had the same problem with my mom's 88 TE -- rough idle, stalling when coming to an abrupt stop, and serious throttle lag -- step on the gas and nothing happens.

I replaced all the rubber vacuum line ends, including all the lines to the computer and to the tranny. This helped, but didn't solve the problem.

I then checked the idle control valve (in front of the fuel distributor under the air cleaner). The hoses were rock hard and rattling around on the nipples. One also holds the cold start valve, and that was loose too.

I replaced them, big pain in the rear, but the throttle lag dissapeared and most of the roughness at idle, although I still have a lean running condition I've not gotten around to fixing.

Check all the rubber hoses that hold vac, and I suspect you need to replace the idle control valve hoses.

Also, see the posts about checking the O2 sensor -- if it is bad, all sorts of strange things can happen.

Peter