95 E320 notchy acceleration - PeachParts Mercedes-Benz Forum

kidMoBile · #1 02-06-2006, 02:06 PM

Hi All:
My wagon has recently seemed very low on power. It's not pulling like it used to at all. In fact, it seems downright slow.
When floored, the car accelerates in a non-linear fashion. It will accelerate somewhat slowly for a second or so, then it feels like something kicks in and it starts to accelerate significantly harder, but for less than a second. Then whatever kicked in goes away and it's just accelerating somewhat slowly again. It goes through this cycle a few times before I hit redline.

New wiring harness. OVP was the updated part# when I got the car.

Any suggestions?

Thanks. Brian

Ali Al-Chalabi · #2 02-06-2006, 02:11 PM

The air mass meter can frequently be the cause of the problems you have described. Is the check engine light on or have any codes been stored?

kidMoBile · #3 02-06-2006, 02:14 PM

No lights.
I'll have to check for codes, but check engine light has not come on since I have owned the car, and I read for codes when I bought it and found none. Can codes be thrown without the check engine light coming on?
Thanks. Brian

Ali Al-Chalabi · #4 02-06-2006, 02:22 PM

The air mass meter can cause som running problems like you have described without being serious enough to trigger the check engine light. If you know someone with a M104 HFM engine or have another one nearby, you can swap the air mass meter with a known good one and see of the problem goes away. That would be a quick and easy way to see if the air mass meter is the problem.

dtf · #5 02-06-2006, 02:52 PM

The MAF would cause the idle to be erratic too. Do you have that as well? Check your plug gap, are they old? - just went through all of this. Bosch F8DC4 is the best for the M104. check out similar post just below this one...

kidMoBile · #6 02-06-2006, 03:02 PM

Thanks for responses so far.
The car runs great other than lack of power and the notchiness when floored. Idle is smooth and at correct rpm; very consistent. Step on it and it just has no guts at all. Car is maintained at dealership, it just had 90K service (plugs changed) late last year. Problem existed before the 90K service and no difference after. Could this be a bad coil?
Thanks. Brian

dtf · #7 02-07-2006, 10:32 AM

could be three bad coils...

Arthur Dalton · #8 02-07-2006, 10:45 AM

Go get the codes pin 8 and 14.

E320 16 PIN DTC Charts inc. pin 8, pin 14

kidMoBile · #9 02-07-2006, 04:26 PM

Gotta build the code reader; I'll update with results. Thanks!
Brian

kidMoBile · #10 02-09-2006, 11:39 PM

and codes finally retrieved!

Some background on the car first:

1995 E320 wagon, 101K miles bought 3-2003 @ 52K miles.
New wiring harness 6-2003.
The "good" OVP part number was on the car when I got it.
The car does NOT have ASR.
Serviced regularly at dealership.

Built-in reader is giving Code 4: "Air injection system faulty hot film mass airflow sensor with hot wire"

Pin 8 gives Code 13: "O2S (Lambda) control system operating at rich or lean limit"

Pin 14 gives Code 11: "Fuel safety shutoff to LH-SFI control module"

Can someone check and see if I'm reading from the correct list? Thanks!

I'm a little fuzzy on the reading method. I hooked the reader up as specified, pushed the switch for 2 seconds, read the code. How do I then check for other codes on the same pin before erasing? I'm paranoid that I may have missed something. What I did was just wait 30 sec after retrieval, then pressed for 2 sec again, but I just got the same code. Then I removed reader, shut off ignition for 40 sec, turned ignition back to on position (didn't start the car), hooked the reader back on and pushed for 2 sec again...got the same codes again. Then I just erased and now it's one blink for all except the built in reader, as it should be.

While checking for codes, I noticed that the throttle actuator (I think it was the actuator....directly under the intake) was making a racket....an electrical whining sound which clicked and changed pitch a couple times as I was clearing the codes out. It was not terribly loud but it definitely got my attention.

Thoughts? Thanks!!
Brian

skiier3_9 · #11 02-10-2006, 09:56 AM

It sounds like you read the codes correctly. To see the "next" code for a particular diagnostic pin you just keep trying to read codes (hold the sw. for 2-3 seconds and then count the blinks) if you get the same number of blinks you've read all the codes. The diagnostic system displays the codes in ascending order, once you've read them all it will cycle through and display them again.

kidMoBile · #12 02-10-2006, 11:14 PM

Anyone have any ideas as to the source of the problem? I'm thinking it's completely MAF related, but I sure would like to hear what others think.
Does a properly functioning throttle actuator make a high pitched humming sound when the ignition is on with car not running?
Thanks. Brian

kidMoBile · #13 02-15-2006, 06:25 PM

Codes were cleared days ago....now pin 2 only shows one blink, and pin 8 again shows fault code 13, but pin 14 code 11 is not there (yet). Wife has been driving it...the car seems to have regained some power, but that notchy acceleration feeling is still there.

haasman · #14 02-15-2006, 11:50 PM

My wagon has always been somewhat notchy in this way, especailly right off the line.

I was told it was a bad throttle cable offerring too much resistance.

Another said it was bad motor mounts!

I did lubricate whatever linkage I could find and as I recall this helped somewhat. Might want to isolate the cable and see if it is twitchy.

Haasman