I HAVE AN 89 300SE! When I accelerate it has a pretty bad hesitation/stumble. I have done a major tune up, changed the coil, fuel filter, cold start valve and cleaned the injectors. Any idea what could cause this? After I cleanerd the injectors, the problem was better for about a day. Thanks, Steve

How about plugs? That was the issue with mine...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

How did you clean your injectors? Some sort of stuff added to the gas? If that temporarily helped it I would bet you need injectors. I think they're around $130 a set? I heard someone say here that MB gas injectors have a service life of around 100k miles. Don't know if it's true or not, but I wouldn't think it impossible either.

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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I had a similar problem with my 300 SEL. I replaced the injectors, went throught the fuel system extensively to no avail. The soultion for me was to adjust the mixture screw at the top of the fuel distributer. This should be done with an exhaust gas analyzer. However, if you have a mechanic set it up based on factory specs it will probably still stumble. Used the trial and error method and solved the problem. ( you can't do this if you are in a state which tests your emmissions system during state inpections)

Do a search on "adjusting EHA". Lots of info and links on adjusting fuel system with & without meters. I'll bet that 1/4 to 1/2 turn of the right screw will smooth things right out.

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Norm in NJ
Next oil change at 230,000miles

I seriously doubt it is the plugs or the injectors.

Lenny is probably on the right track. I'm going to guess that you replaced the EHA (cold start valve) and you now need a mixture adjustment.

You don't need an exhaust analyzer. http://www.landiss.com/mixture.htm

That site explains the procedure.

Try setting mixture around 45%.

When exactly does the car stumble? Time from start, engine temp etc?

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'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E