Mike69:

If your car has a 1989 M103 engine, a good independent should be able to resolve the problem without OBD equipment. This comment is not intended as a slur against MB dealers.

I may stand corrected, but I do not believe OBD was around in 1989, at least not on the '89 M103.

An ignition scope could be used to check ignition.

Steve Brotherton's article on engine mgt. is also quite useful.
One needs TWO multimeters. One to test EHA current and one for the X11 diagnostic port. You'll want to use a multimeter with duty cycle capabilities for the X11 port. The EHA current test may be done with a std. no-frills multimeter; however, it must be able to read milliamp.

By the way, the EHA test harness that was $20 a few months ago is now close to $40.

Thanks a lot for the valuable info guys!

I will buy a new set of Bosch H9DC today and keep you posted on my idle. I hope it improves with the .36 gap that I set it to.

I'm confused. I thought the thread started after you had already bought a set of H9DC. ?

I am buying another set apart from that new set I previously bought. I am going to set one set of plugs at .36 and another set at .38 or .40. I plan on testing both sets to see which performs better in my car.

You don't need another set. You can gap them back and forth. I wouldn't do it 50 times, but you can do it 3 or 4 times with no problem.

Well the Bosch plugs are on sale for $0.69 at Pep Boys until Aug. 9. Save $0.39!!!

Well, I don't guess I can argue with you at that price :-)

Installed a set of Champion Platinum plugs in my C280 about 85,000 miles ago. Never checked the gap and have not done anything related to the plugs since. Car runs perfectly and I wonder if it will ever wear out? But keep in mind, MB are almost maintenace free and require very little under the hood adjusting. Really, they are very much like Fords and Chevys.

:confused:

Amazing
 

<<Installed a set of Champion Platinum plugs in my C280 about 85,000 miles ago. Never checked the gap and have not done anything related to the plugs since. Car runs perfectly and I wonder if it will ever wear out? But keep in mind, MB are almost maintenace free and require very little under the hood adjusting. Really, they are very much like Fords and Chevys.>>

Are you sure this is a Mercedes? Maintenance free? 85000 miles?

Maybe it's a Mazda or a Mercury or sumpin' else beginning with M.

That line made me laugh. If MB's were so maintenance free, why is mercedesshop.com so popular for our problems???

that's a good question.

i own a number of benzes. by and large, they are bulletproof. there has been nothing mysterious about them. i tune into this site hoping that someone will respond, finally, to a question i raised months ago. so far, no one has. and the dealer doesn't want to deal with the issue either.

i won't go into it, now, you can research my posts. but it involves the seats in a 1997 s500 coupe. they don't want to do as the manual says they should. why?

a computer chip glitch?

this is a fascinating site, but it has never answered my questions.

so it goes.

No one has answered my question, either. Here it is:

"If it takes 1 hour to dig a hole, how long would it take to dig half a hole?"

Seriously, though -- sometimes no one knows the answer. Although, we could do a better job of "trying" to help narrow it down.