I tend to have a miss or hiccup in my 1990 300CE. I have replaced the ignition wires, rotor, distributor, plugs. Fixed vacuum leaks.
It tends to have more when the weather is hot, than when it is colder outside. I also replaced the fuel distributor. There was some improvement but did not fix the problem. Also, I use only super unleaded fuel.
One mechanic had fixed this problem, where he replaced all the spark plug boots with older style VW boots, which are all plastic, I think these did not have any resistance values. The car ran sate mooth for a year.
Unfortunately, this mechanic retired and moved.
He had kept the car for like 1 week to fix this hesitation issue.
When I tried to remove these VW spark plug boots, they broke.
So, I replaced the ignition wires with factory set.
I have also noticed that if I accelerate slowly, it tends to miss less.
The spark plugs are not wet. I also tried Bosch vs. NGK (regular not platinum) NGK tends to have less miss.
Any ideas??

have you replaced ovp relay?

__________________
David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

What's the OVP relay, David?

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" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

Yes, I did replace the OVP relay, made no difference.
I love this car except for this hesitation.
One moderator Steve Botherton in Florida, knows about this
and I think he said to replace a BOSCH part inside the mass air
flow sensor but then it has to be calibrated which most of the
average MB mechanics quite dont know how.
One mechanic did meassure some electrical value (either the current or resistance??) at the mass air flow sensor upon giving gas, that he did not see
the change normally seen. Whatever that means.
Quite not sure.
The car starts up fine, except for the hesitation upon accleration from a complete stop. I also tried BG-44K cleaner twice, no real difference.
Any MB gurus??

If I recall correctly, you have struggled with this problem for a long time.

I also read the same problem you post in other forum.

I have the same car, same year, same problem, until last time I replace the spark plugs. Now, I know you replaced them already. Here is the million dollar answer to our hesitation agony-- make sure you torque them to 20 ft-lb! That is the torque specs from owner's manual.

Try it, my problem on hesitation is forever solved.

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11 S550
09 C300
91 560SEL
90 300CE
84 380SE
83 240D