My 1995 E320 with the M104 engine has an occasional hesitation problem upon acceleration.
The car has 139,000miles and runs VERY smoothly about 85% of the time.
Occasionally (about 15% of the time)upon a hard acceleration (with the throttle position beyond about half-way) the engine exhibits a stumble, and continues missing as RPM is increased....and 30 seconds later runs smooth as silk. If the throttle is opened quickly (for passing), I have noted a hesitation and "pop" (definitely an engine backfire, thru the intake). This backfire symptom indicates to me that the engine is temporarily way too lean!
I have checked the EGR system with a vacuum pump and have cleaned the EGR valve....works Fine. I also performed the EGR line (to the intake) cleanout procedure with a speedometer cable, that Steve Brotherton recommended...[this appeared to work through and clean the soot in the line, however, this work had no effect on the engine performance. This car has never had the engine electrical harness replacement......I was wondering if there is some problem related to the throttle position sensor and the engine fuel management system....due to the engine harness problems??????....causing occasional lean conditions.
Your advice on this issue is welcome!
Thanks,
Steve Whiteside

Steve,

Does the car ever exhibit problems with acceleration from a standstill and/or hesitation while sitting idle? If so, you may have a wiring harness problem. 124s were known for them with the 104 engine. I had the above symptoms with my '93 300E 2.8 (since sold) and after I replaced the harness and coils, everything was fine and dandy.

__________________
Regards,
Aaron

I had the same problemss.... do a search on "acceleration resistance" to find my problems with my M104 motor!!

Three things....

Front Flex Disc
Lower Cntrl Arm Bushings
Plug wires, coil ends, & spark plugs.

Good luck!

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

David & Aaron,
Thanks for the timely feedback and advice! My E320 starts easily and always idles fine. I think my problem is very similar to the one David described as Acceleration Resistance [in the archives].
I will replace the coil ends and plugs and report back. [I replaced the front flex disk last year].

David, by the way, I still have the automatic downshift "clunk" as the car drops into first at about 10mph. Were you successful in figuring this out on your car???
I recently noticed the gas tank doorflap is sticking [and hence may have a vacuum leak].....possibly this vacuum leak could have an effect on the transmission modulation for the downshift to low?? [the upshifting is perfect].

thanks,
Steve Whiteside
'95 E320wagon
'81 300TDT
'59 220SE Ponton 4-dr Sedan

I believe the downshift thunk went away when I changed the front flex disc. I know the rear flex disc lasts a bit longer... but maybe it could be the rear? Maybe it should be inspected. How many miles do you have? Also maybe check the drivetrain mounts.... ie differential mounts, trans mounts.

I don't think that your fuel door vacuum is related to engine vacuum... it is operated by the vacuum pump, which is not related to the vacuum suppled by the engine (i believe?) which controls trans shifting.

GOOD LUCK!!

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

David & Aaron,
I took your advice, but changed ONLY the 3 coil connections from the coils to the plugs. Total cost = $33 from dealers parts counter. This work took 20 minutes......the car is running like a new one with no hesitation or miss.
THANKS!
Steve Whiteside
95 E320 Wagon M104 Eng

Glad to hear the car is running beautifully again!

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Guys,

Are these the "Ignition Wire End Plugs", as listed in Fastlane? They're about $10 each and described as the 90 degree connector at the coil.

I want to replace these as preventative maintenance, but I want to get the right parts.

Thanks!

__________________
D.H.

04 ML500
02 E430

Experience is something you don't get until just after you need it.

No.
You want the 3 under the coils. No wires involved .
Plug #s 2, 4 , and 6.

FastLane

F1010--84561 Beru-- $7.96
Quanity-3

PS
Your old ones will have the Benz # 000 159 35 42 on them if they are original.
That # has been updated to 000 159 36 42. That will be on them if they have been changed.

Thanks Arthur!

Dennis

__________________
D.H.

04 ML500
02 E430

Experience is something you don't get until just after you need it.

I believe the gas cap door is part of the central locking system vacuum pump. I just had mine changed and the new pump wouldn't let go of the gas cap door. Had to open it manually from inside.