worse on lower speeds.
Background: My car was running perfectly until yesterday. I went to a store and while waiting outside with the engine on (for about 10 minutes) the engine started to miss and shake. I turned it off immediately. I restarted the car about 10 minutes later and now I have a rough idle and lack of power throughout the power curve. The car shakes and hesitates when under load. It gets better and the speed increases. It is NOT temperature dependant because it happens all the time now. There are no lights on.
I bought a fuel injector cleaner and it is in the tank now (no change so far) but, I don't think it is fuel related.
After reading the archives, my two top suspects are ignition coil (because the problem is worse under load) and/or a plugged cat converter (since temperature can affect the cat and can cause problems under load). Is there a simple and accurate way to test these items. Although, I must admit that I do need a distributor cap and rotor, based on mileage alone.
My car has over 200K and is "eating" oil.
Any other ideas?
Thanks!

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J.H.
'86 300E

Eating oil....Check for oil fouling on spark plugs,if fouled,replace with new plugs,see if theres an improvement,if so find source of your oil consumption;possibly by doing a leak downn test.

I just checked the copper plugs. All of them have heavy ash deposits and one has a sign of detonation, part of the "boot" of the electrode is missing. I will change them all tomorrow and hopefully that will clear the problem. The thing with the plugs is that they were installed about 10,000 miles ago but...now that I think of it, I did changed the fuel distributor since then, hummm...

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J.H.
'86 300E

y don't u swap out the distributor caps/rotors for new ones? you said they gotta be changed anyways...my car had the same trouble as yours...the dealership diagnosed it as caps and rotors...after they changed it for new ones, the problem went away...

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1995 black pearl/black Mercedes-Benz E420 :

I replaced the spark plugs and...the problem went away.
I also bought the rotor and distributor cap but, I did not install them yet. I have plans to do a head job myself (the car has over 200K miles) in the next couple of months so I will save them until then.
I still don't understand why it happened all of the sudden!
Thanks for all the help!

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J.H.
'86 300E

If the problem reoccurs in 200 - 300 miles your resistor ends are shot. You'll have to replace the ends and the plugs again.

You could have a plug end problem as stated. Reducing firing voltages by replacing plugs can cover up such problems.

Leaving your car idling (probably with A/C on) on a summer Florida day for extended times is a definite stress test. you stressed it and it suddenly broke, seems logical to me.

BTW, why haven't you replaced your valve guide seals and dealt with the oil and spark plug consumption?

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I will investigate the plug wire ends. Although, cylinder number 4 had the problems with detonation? and that is the one that had an injector seal air leak recently (replaced since then). Coincidence?
Steve,
The valve guide seals were replaced about 20k miles ago and, at the time, I was told that the valve guides were loose and I would have to replace them in the near future. I also have the "typical" front cover seal leak. My car has now over 240K and it is consuming about a quart of oil every two tanks of gas.
I think it is time...

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J.H.
'86 300E

Yep, 20k is too little time on the seals. Thats the way you know its time when they only work that long.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician