94 E320 needs smoothing out
 

Hi all:

My 1994 E320 runs great, but at full throttle the acceleration needs some smoothing out. When accelerating on a freeway ramp, for example in 2nd gear and pulling from 3,000 to 5,500 rpm it feels like there are "flat spots" in the torque curve instead of just pulling steady.

I know it's not a fuel filter because it will get to the high revs just fine. I suspect that the injectors may be dirty, but I'd like to troubleshoot it more first before spending money on it.

What are some common areas that I could clean, test, confirm operation of, etc.? Please share your ideas and experience!

Thanks!

I'd bet money your air mass sensor is bad.Very common.The best way is to test via actual values with HHT or SDS (MB dealer scan tools).
I can't promise you anything,but from experience,put one on.
It is the large sensor attached to the air cleaner box between box and tube going to the intake.
MB part # 000 094 05 48
Brian

Thanks for the suggestion Brian.

When I do a search here I see that the mass air sensor is a very common problem on the 94 E320. However, I also see that the symptoms are commonly an erratic idle. Do you frequently see symptoms like mine from the bad sensor as well?

If that's the only or most likely cause I'll have to go get it scanned.

Any other inputs or ideas?

Thanks again!

If ignition codes come up, a common fault [ and easy fix] on the E320 - 104s is the three plug connectors under the ign. coils.

I see symptoms exactly like you describe.
Brian

Solved - follow up
 

Thanks for the help on this.

The problem was a dirty air filter! Shame on me!

Normally I change them every 3rd oil change, or 9,000 miles. I've only had this car for 6,000 miles so far, and it looked pretty new when I got it. I changed the stock filter out for a 3-stage foam filter and my problem went away. We're breathing freely now!

Arthur, I checked my coil-to-plug connectors and they are the old part numbers, indicating that they are original. Per everyone's experience here, I am going to upgrade/replace them with the new part number.

Next I need to check my OVP to see if it's the original Siemens part. If so, it's next.

Brian, I'll file your diagnosis away for next time - but hopefully I won't have to replace that mass air sensor anytime soon (not cheap!).

Thanks again.