Having a little problem with a minor misfire around 2500 rpm no misfire under heavy load or acceleration that I can notice.
New spark plugs and 02 sensor change the 02 sensor for a hesitation under slow acceleration and solved the problem but not the misfire. EGR valve tested ok and if that was the problem I guess I would have some other problem.

Spark plug wire and distributor measured and look ok and I think if this was ignition related I would have problem under heavy load and acceleration.
When I think about it I guess it could be a bad ground some where.
Any thought around the problem is welcome do not ask me what car it is.
Because it is a Toyota 1992 3s-fe engine with a distributor with build in ignition coil and igniter, and EFI injection and EGR valve and modulator.
I have reading this forum for 12 years when i bought my E 320 W124 and there is a lot of experience guys around here whre I can't find somewhere else.

sound like a valve miss at certain rpms,most time valves have a high speed miss.Or if a M104 with coils they can do it.As far as grounding a motor,I always add better grounds to engine to chasiss,and one from batt to motor a extra

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

It is not on my E320 the problem occur. It is on a freinds Toyota sorry if I am confusing you guys posting on Mercedes forum it is only because a have seen a lot of people that understand engine performance diagnostic at this forum.
I have a steady vacuum when I check engine and the car have not hydraulic valve lifter, it's a odd problem if there was a valve problem I guess I should have problems at higher rpm but I have no problem at full throttle.
I guess I should see the problem on the vacuum gauge but I am not.

is it solid lifters that adjust/ I try that first,because it might be not sealing perfeect..I never heard of a plug doing that unless your head has something in it. some engines do not like fine wire modren plugs.They perfer a large flame kernal

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

The problem solved ignition timing off 10 degree car runs great now.

was it 10 degree less?

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

This it at the Toyota and with a distributor the initial ignition timing should be 10 degree advanced instead the timing was at 0 no advanced just helped a friend who just bought the car. I still got the Mercedes E320 runs great with 350 000 miles on it just need some new shock absorber.