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1995 E320 (W124) Wagon
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16 Posts
Discussion Starter · #1 ·
Hey guys,

I recently bought a 1995 E320 wagon that would randomly shutter on and off while in idle. It was like a hiccup and it would come and go. However, I could reproduce the problem without fail by idling in gear with the A/C on. It's a common problem and I've had my fair share of surfing the forums for a fix. Good news is that I fixed the problem.

For the benefit of everyone else, here's the chronological progression of what I did and what happened.

Changed Spark plugs => Didn't fix it (previous owner)
Changed Ignition Coils => Didn't fix it (previous owner)
Cleaned the Throttle Body => Didn't fix it (It was REALLY dirty and now the car accelerates smoother)
Changed Wiring Harness => Didn't fix it (But I had to do this anyway since the wires were in such a poor condition that I didn't feel comfortable driving the car. When I opened up the ignition wires, the insulation simply disintegrated in my hands and was shorting)

THE FIX: Changed spark plug wires.

After changing the spark plug wires, I've noticed a much smoother drive and more power. The old ones were the original :)eek:) and there was obvious corrosion of the connectors that contact the spark plugs. This explains everything. The corrosion increased the resistance of the wires which prevented the plugs from getting their required voltage to light all the gas/air mixture and so the engine would occasionally misfire (shutter). This especially happened when under moderate load (A/C on and in gear). This also explains the increase in power after installing the new spark plug wires. The plugs are now getting their required voltage and so it's able to burn more of the gas compared to before, which gives more power.

Again, I know that I should have done it in increasing cost, but the wiring harness had to be changed anyway. It was a known problem with the car when I bought it, so I already priced that in to my decision.

So I hope this helps others out there who may be experiencing something similar. If you have any questions, I'll try to entertain them.
 

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Registered
2001 E320; 2002 ML500
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1,982 Posts
Congrats on the fix. Too often spark plug wires are overlooked. I replaced mine at about 190K; old ones were in good shape but since I was replacing the plugs, I figured I replace the wires too.
How did you clean the throttle body? Please explain as this is useful info.
Thanks
 

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Premium Member
About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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5,506 Posts
Good info and thanks.
I recently replaced the ignition cables on my 88 TE#2. This car has 205k miles and the ignition cables were the original ones!
I noticed their condition when I did my first stem to stern inspection after buying the car in February of this year and planned on replacing them soon but other events (disasters) got in the way. The worst one onmy car was the cap-to-coil cable that was cracked, blistered, and super stiff in the area where it is clipped to the cap shield.
When the impala 89 300E showed up in the local U-Pull-It a couple of weeks ago I couldn't help notice that the ignition cables looked fresh. Yep, Beru brand with a 2004 date code. For the price (distributor cap, rotor,and cables = $10) I *had* to take them.
 

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Registered
1995 E320 (W124) Wagon
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16 Posts
Discussion Starter · #4 ·
Throttle body cleaning

Congrats on the fix. Too often spark plug wires are overlooked. I replaced mine at about 190K; old ones were in good shape but since I was replacing the plugs, I figured I replace the wires too.
How did you clean the throttle body? Please explain as this is useful info.
Thanks
I'm glad that people are finding this useful. I cleaned the throttle body with throttle body cleaner (I know ;)) that I picked up from an auto store for $5.

The procedure: 1. Remove the overhead manifold that goes over the engine (the same one you need to get off to remove the engine cover).
2. Remove the black box sitting on the intake manifold. There are 4 hex screws, two are exposed and the other two can be uncovered by removing the rubber caps on top of them. Once you get the screws off, you just need to pull gently (it takes quite some force).
3. Remove the cylindrical rubber extender that goes from the throttle body to the overhead manifold. It was tricky getting to the screw of the crimper. And then even after that, it was still hard to get off. The trick was to put your hand inside and push against the walls to try to loosen it.
4. Remove the 4 hex screws on the throttle body and take it off. Be careful when removing the throttle body since there is a spring, a lever, and a few other connectors that are attached directly to it.
5. With the throttle body off, just take out your can of cleaner and spray it and wipe it off with a clean cloth.

It's about a 2 hour job. This is definitely DIY for a person with medium technical experience.

Hope this helps. I'm eventually going to post (with pictures) my experiences to help others who may be in need to DIY help.
 

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1995 E320 (W124) Wagon
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16 Posts
Discussion Starter · #5 ·
FYI: I Just added a guide with pictures on how to clean the throttle body.
 

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Registered
2001 E320; 2002 ML500
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1,982 Posts
FYI: I Just added a guide with pictures on how to clean the throttle body.
Thanks! I saw the post with pictures. Very helpful.
How was the condition of the throttle body wiring harness?
 

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1992 190E (W201) 2.6L
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332 Posts
You're doing a great job in documentation and troubleshooting!!!:thumbsup:
Keep it up and keep us informed.
 

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'94 E280 T
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587 Posts
And you are doing and EXCELLENT part man... :)

I've just recently experienced the misfire under moderate load, havent noticed anything wrong when driving normally... just at idle and under load.

I'm alreay digging ebay for some spark plug wires.

Thanks for the troubleshooting report and keep it up! :)
 

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90 Posts
I have a 95 E320 and only had it two years. I know the previous owner took good care of it. I am noticing a shaking when starting the car in the morning afterwards backing up and going forward. While driving it's ok, but stopping at a light it starts again. After putting gas treatment it seems better now. I have changed my spark plugs. Ignition wires look ok. Another problem I am having is my front speakers. Ther right speaker in general gets distorted on and off. They are new and had them tested and they are fine. Other people on the forum has similar problems no matter what model they have. Any suggestions?
 

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90 Posts
No I don't have the URL of how to clean the throttle body. I would appreciate it if you give it to me. If it's not hard I can do it myself. Thanks!
 

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1995 E280
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84 Posts
Ignition wires can look ok when they are actually not. They leak EMI. I changed to Magnecor and it made a huge difference.
 

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Registered
95 E320 (Sold, known as Hi Ho)..1990 300E (sold, known as "the Chariot"..Current
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160 Posts
Source for M104 Spark Plug Wires?

Where did you get the plug wires for the M104 (I have a 1993 300E with the 3.2l engine - M104)?

I called local dealer and they said they were $309 and had to order them...

Tomer
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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13,096 Posts
Tomer,

If your car is a 93 and is indeed the twincam M104 motor, then it's a 2.8ltr. Go to Autohausaz.com or Autopartsplace.com and shop for the plug wires. To my knowledge, there are only two spark plugs out there (in the US) that meet OEM specs for non-resistor plugs. On Amazon.com, check for NGK - BP6EF or Denso - T20EP-U. The plug wire connectors, at the plugs, are resistor connections so you do not want to run a resistor plug. I run the Denso's in all three of my MB's.. perfect

Good Luck,

Jayare
 

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Registered
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90 Posts
Hey guys,

I recently bought a 1995 E320 wagon that would randomly shutter on and off while in idle. It was like a hiccup and it would come and go. However, I could reproduce the problem without fail by idling in gear with the A/C on. It's a common problem and I've had my fair share of surfing the forums for a fix. Good news is that I fixed the problem.

For the benefit of everyone else, here's the chronological progression of what I did and what happened.

Changed Spark plugs => Didn't fix it (previous owner)
Changed Ignition Coils => Didn't fix it (previous owner)
Cleaned the Throttle Body => Didn't fix it (It was REALLY dirty and now the car accelerates smoother)
Changed Wiring Harness => Didn't fix it (But I had to do this anyway since the wires were in such a poor condition that I didn't feel comfortable driving the car. When I opened up the ignition wires, the insulation simply disintegrated in my hands and was shorting)

THE FIX: Changed spark plug wires.

After changing the spark plug wires, I've noticed a much smoother drive and more power. The old ones were the original :)eek:) and there was obvious corrosion of the connectors that contact the spark plugs. This explains everything. The corrosion increased the resistance of the wires which prevented the plugs from getting their required voltage to light all the gas/air mixture and so the engine would occasionally misfire (shutter). This especially happened when under moderate load (A/C on and in gear). This also explains the increase in power after installing the new spark plug wires. The plugs are now getting their required voltage and so it's able to burn more of the gas compared to before, which gives more power.

Again, I know that I should have done it in increasing cost, but the wiring harness had to be changed anyway. It was a known problem with the car when I bought it, so I already priced that in to my decision.

So I hope this helps others out there who may be experiencing something similar. If you have any questions, I'll try to entertain them.

I have similar problems and I have changed the spark plugs and ignition wires. Starts up fine but when backwards or forward the car vibrates. I've had some suggestions and they were it could be the motor mount, hmmm.....what does that have to do with the rpm's going from 800 rpm's to 500 rpm's? It's puzzling and I definately don't want ot take it to the dealer.
 
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