Kevin J-H

MY 1989 260E misses between 1500 and 2000 RPM. I have replaced the distributere cap, plug leads, fuel filter and both fuel pumps, spark plugs and coil. none of these items have overcome the problem. The vehicle starts first crack everytime cold and hot so it can't be the cold start valve or the injectors. Any ideas as I don't want to take it to the garage as they will only guess the issue as I have. I was wondering if the alternator may be the problem as the dash lights brighten and go normal whilst driving at night. Yes the battery has been change also. Both fuel pumps are running fine. It is a mystery, HELP.

ps2cho

I doubt the problems are connected, but check the alternator anyway using a DMM as the lights should not get brighter/dimmer while driving unless you are pressing windows/got a huge subwoofer installed etc...

Have you replaced/checked the rotor? What color are the spark plugs? What type of spark plugs are in there?

Kevin J-H

No, I did not replace the rotor only the distributer cap.

I have +14 HR 8 DC+ Bosch super plus.

I will have the alternator checked out also.

Thank you for the tips

ps2cho

Start with getting rid of those plugs as they are wrong for this engine. Go with NGK BP6EFS,
Champion S12YCC, or the OEM Bosch H9DC0 (NOT H9DCR0). You want non-resistor plugs.

I'd check the rotor at the very least, if not replace it. Its a $30 part that is general tune up item.

epowers777

I recommend nology spark plugs. Go to nology.com

epowers777

just bought the ngk plugs for my 300e that Im selling. Less than 20bucks.
My nologies are 60 buck im keeping those.

http://cgi.ebay.com/NGK-spark-plug-B...3286.m63.l1177

Kevin J-H

Well I have replaced the plugs as suggested and the rotor cap in the dizy.

Now when it starts it seems to hestitage and give out a little miss before running. Sounds like when a car is slightly flooded.

It still misses within the same RPM range.

I have not taken out the Cold Start Valve - could this be the issue and in fact the car is flooding due to the CSV leaking? once above the rpm range it performs well no missing. (When it misses the car does not jerk, its performance is smooth but performance is down, during this event)

Any further ideas apart from going to the MB garage?

ps2cho

The EHA tends to cause a lot of bottom end power issues....although I havn't heard of misfires, I guess it could be possible.

Got a junkyard near you? If so, might be an easy swap to rule it off.

Kevin J-H

Well I have tried everything suggested and thank you for the suggestions.

Smae problem exists

Could it be the mixture screw that sits under the air cleaner.

If the mixture was not spot on would this provide a miss within a rev range??

epowers777

could be injectors or vacuum leak. Spray carb cleaner around injectors while revving see if its sucking air. Also injectors leak while in idle and some times will spray funny under load but will idle fine. So could be injectors. Dont mess with that screw speaking from experience. Have you already?

ps2cho

All you need is the A/F ratio to be close to 50% and that is it. Once it is at 50% leave it alone! The system is designed to automatically compensate once in closed loop.
At 50%, it allows maximum adjustment from the computer system.

epowers777

https://mbworld.org/forums/e-class-w...ntiometer.html
Thats for adjusting that screw ask ps2cho if you got ???