Help - 95 E320 running rough/idling rough
 

I have a 1995 E320 w/ 180,000 bought used at 145,000. Car has been idling up and down (surging ) for about 4months but yesterday it has started to accelerate sluggishly and this morning it "backfired" on me. Its as if the fuel filter is dirty but I dont think that is the problem. The ECU codes are 10,16 and 19. Could this be a O2 sensor gone bad?

Sounds more like a bad wiring harness to me. Do a search, massive amount of info on this common E320 defect.

engine runs smooth at idle except for the surge now and then when i "floor it" thats when it sputters. I am having a hard time going up hills

plugged cat. converter?

funny you would say that. i have a BMW mech friend that i talked to today and says sounds like o2 sensor and/or cat converter going bad. It has had a strong smell like gas /sulphur last 4-5 months you think he is right?

sounds about right to me.

A surging idle is not caused by a plugged cat.

I'd check for:

1. vacum leak
2. bad mass air meter
3. bad throttle actuator

You also need to replace your engine wiring harness before you do any other diagnostic work.

I went to Maxi muffler and they did a test/ They said that the cat convert was indicating a blockage but not enough to do what its doing. They sd maybe a combo of things. I am taking to Precision Tuneup tomorrow to see what they say. ASE certified so they say......

Try changing the coil. I just got my hesitation problem resolved. Look up my last post for the details.

jrmd01

You are ignoring the obvious.

If the idle is fluctuating up and down, it means the mass air meter is struggling to find the proper mixture of air to fuel. It obviously can't.

This means that you either have a vacum leak somewhere in the system, introducing "false air" into the sytem, and preventing the mass air meter from working.

It also might mean that the mass air meter itself has gone bad.

Likewise, a faulty throttle actuator causes the same symptoms.

A problem like yours is very characteristic on this engine. It is always one of the three above issues.

Search the archives. There is tons and tons of info on your issue.

Last, take your car to a Mercedes specialist. The average run-of-the-mill shop will not have the expertise to properly diagnose your car.

Which one do you suppose he should change ???

As always this website has been always so informative. I thank everyone for their input. It hassaved me hundreds of dollars so far. Anyway,how &where is the throttel actuator and mass air flow? About how much do these itens cost?

J

The mass air meter is in the black plastic tube that connects to the air filter box.

It takes about 10-15 minutes to replace, and costs about $250-ish the last time I checked.

The throttle actuator sits underneath the intake manifold, and costs around $1,500.

With the questions you are asking, I suggest you take it in and have a mechanic that specializes in Mercedes.

Before you spend hundreds of dollars, it could be a simple vacum leak, i.e. cracked hose. There's a switch over valve at the front of the engine with a vacum hose that cracks from heat.

wiring harness
wiring harness
wiring harness

On my car (86' 300E), there was only one coil. I'm not sure about the newer models...I think I've read somewhere that there are 3 coils??? In that case, it might be more cost effective to take it to a mercedes mechanic specialist. I paid $145 (one coil), $18 (6 Bosh sparkplugs), $90 (labor + "scope").

Without actually physically inspecting and putting the car through a thorough diagnostic examination, we are all just guessing. But it's nice to know what the POSSIBLE SOLUTIONS are. This problem could be anything from MAS, wiring harness, throttle body, sensors, filters, coil, or even relays.

My 104 surged too, I have a 96 so it was not the wiring harness but a vacuum leak from a bad Purge valve that was not closing. After that was replaced the car ran like new. If it isn't the cat it is likely something air related (MAF, vacuum leak, etc..) or your harness. Your harness connects all the electronic devices to the computer and the computer controls the idle, when there is a bad signal the computer will increase the idle to compensate for what it things is increased air flow. Good luck!
Brian

Your car has diagnostic code storage for the different modules/systems. So, you may want to go see what the Diagnostic Code System has stored for the HFM/SFI Engine Management module and the Accelerator Module.
This helps eliminate Guessing..
This can be done by looking in the Archieves for both the codes and the Tool needed to get them .
The tool is a simple home-made LED Retrieve device that cost about $5 to make.
These EFI units have quite a bit of storage capability and the pins I recommend you retrieve from will be both #8 [ HFM Module] and #14 [AE/CC module].
You have given the CE lamp activation codes , but they are not as refined as the actual systems ones for pin-pointing faults/conditions.........
..or, just have a Tech scan these other modules.

Problem Solved
 

Hey guys/gals as always - You all have helped me save 100.00's of dollars. I spent $9.50 on 6 spark plugs and put them in myself (real easy on 1995 e320 ) Now runs great. The sparks plugs had white deposits and rust on them. The surging is sporadic / I think thats another issue. Anyway thanks again for everyone's help

J :) :)