95 E320 Stumbling Idle - Page 2 - PeachParts Mercedes-Benz Forum

95E320cab · #16 09-01-2002, 04:01 PM

I had very similar symptoms with my 95 E320. After going through several sets of plugs, I went to the owners manual and got the correct plug number. Parts stores had a "replacement" plug, but it still ran like crap. I got the correst plugs from the dealer - a little more but worth it. At the same time I replaced the resistor ends on all six plug wires. I believe this was the offending part, as I have since had no other problems. It was also the path of least expense, considering I was looking at replacing mass airflow sensor, etc. I ordered them from Performance Motorcars for about $65. A quick fix. I suggest you get the right plugs and replace the resistor ends. Bet it works.

Dave

#17 09-01-2002, 05:38 PM

Arthur, it stumbles right before I come to a complete stop, I would say it starts at around 5mph to a stop, then a second later it will bounce back to normal. Take off is smooth, no problems there.

And Dave, I replaced the coil boots and the other 3 wires about 5k miles ago along with a new set off correct spec. bosch plugs.

mbe32094 · #18 09-02-2002, 12:01 AM

You may have a defective Mass air flow sensor .
I had a similar problem before. Check my post.
Erratic Idle on '94 E320 Solved!!!

#19 09-02-2002, 09:36 PM

With no codes and variable ohm readings on the mass air sensor, I guess it's possible. I don't know of any sure fire way of testing the one on my car, here at home, without sophisticated equipment.

suginami · #20 09-02-2002, 10:38 PM

Well, FWIW, since it isn't the EGR valve (since he's bb'd the line from the SOV), and since it isn't the wiring harness, I'd be inclined to check your spark plug / coil wires again, and probably check the connection to the wire ends.

After that, I'd suspect the mass air sensor or the throttle actuator. Both are not uncommon failure items on these engines and both will affect idle. A vacuum leak will also cause these two items to act up.

Just hope it's not the actuator. It's about $961 if you order it from this website and a lot more at the dealer. I think the mass air sensor is a little over $200.

#21 09-03-2002, 10:17 AM

Yesterday, I removed all of the spark plugs, looking for any signs of uneven firing and hoping to see if one cylinder was running lean. They all looked identical and I made sure all of the coil boots and wires were secure when I put everything back together. Took it out for a ride and................no difference. Sometimes it will stumble when I come to a stop and sometimes it won't. Weird.

I hoping someone here can tell me a way to verify if the mass air or throttle actuator might be bad. I hate to throw parts at this thing knowing the expense of them.

Dale

miktvk · #22 09-03-2002, 11:35 AM

I have just solved this exact problem with new coil boots; and the wiring harness is bad but still functioning. Diagnostic tester revealed misfire on #6, fixed with new boot.

Easiest way to tell the harness is falling to bits is to look at the wiring at the 3 connectors that run under the removable black plastic cover attached to the front of the valve cover. I think one of these plugs is attached to the cam magnet (?) the other two run farther in. The insulation on the wires (under the outer black sheathing) will have hairline cracks running all around them. If you move 'em around too much its starts to flake away, very nasty.

#23 09-03-2002, 12:52 PM

miktvk,

I replaced all of the coil boots and the other 3 plug wires about 5k miles ago. My harness appears to be in great shape as well.

mbe32094 · #24 09-03-2002, 01:07 PM

As I said earlier your mass air flow sensor may be defective. You can measeure the resistance values as I stated in my post and compare it with your mass air flow sensor readings. You can buy a cheap multimeter at Radio shock for about 10 bucks. This is good enough to give you an accurate ohms reading.