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  #1  
Old 06-27-2006, 06:26 PM
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94 E320...How Many Spark Plugs?

For some reason I thought I read soewhere that 94 and 95 E320's had two plugs per cylinder. Is this true?
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  #2  
Old 06-27-2006, 06:51 PM
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No, that came later on the 112 motor in 1998 E320.
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  #3  
Old 06-27-2006, 06:57 PM
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The confusion prob comes from this system having a coil for 2 plugs.. meaning a "Waste Spark" ignition system, where the coil [ 3 of them] fires two cylinder at the same time, where only one is on compression stroke, so the other is a wasted spark.
So , this system [ and your chassis ] has 3 coils and 6 plugs.
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Old 06-27-2006, 09:07 PM
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Quote:
Originally Posted by Arthur Dalton
The confusion prob comes from this system having a coil for 2 plugs.. meaning a "Waste Spark" ignition system, where the coil [ 3 of them] fires two cylinder at the same time, where only one is on compression stroke, so the other is a wasted spark.
So , this system [ and your chassis ] has 3 coils and 6 plugs.

Thanks very much for the clarification and education...

Tonight I'm tackling the replacement of my engine harness. Picked up the part today at my dealer and am trying to keep the cost down by replacing it myself. Any cautions or guidance is most welcome. I did look over the post on this forum regarding "wiringing harness replacement". I don't have it in front of me or I would acknkwledge the author and express my thanks. I'm off to the garage right now to get this chore underway.
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  #5  
Old 06-27-2006, 09:14 PM
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A worthy tip for you..
On 104 HFM engines , also change the plug connectors under the 3 coils and use only Bosch F8DC4 Super Copper plugs
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  #6  
Old 06-28-2006, 12:59 AM
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Quote:
Originally Posted by Arthur Dalton
A worthy tip for you..
On 104 HFM engines , also change the plug connectors under the 3 coils and use only Bosch F8DC4 Super Copper plugs

Thanks for the tip...

I finished the removal and replacement of the engine harness a few minutes ago. In consideration of your tip, I'm didn't close-up the engine cover, I'll go to the dealer in the morning and purcahse the connectors and plugs as you suggest. Thanks again...
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  #7  
Old 06-28-2006, 06:36 PM
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Quote:
Originally Posted by Arthur Dalton
A worthy tip for you..
On 104 HFM engines , also change the plug connectors under the 3 coils and use only Bosch F8DC4 Super Copper plugs
Arthur, do you mean I should change ONLY the three connectors under the coils? Should I also repace the wiring/connectors to the other three plugs as well, or leave alone?
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  #8  
Old 06-28-2006, 07:44 PM
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Just the coil ones ..
They are trapped in the heat by the coil being on top , along with their poor design of not having a snap type connector to the plug like the other 3 do. They use a spring pressure because the coil holds them in place on the plug. but the springs get heat fatiqued and fail.. very common fail part. The problem with these is when a plug connection fails , it can foul two plugs b/c of the waste spark series circuit. ..and then the ECU detects an ignition misfire and shuts down the signal to the HFMSFI injectors so the cat does not fill up with raw fuel.
So, a simple poor connector under the coil can cause the crappiest ruinning 104 you ever saw..
Any tech that works on 104 HFM will just change the connectors whenever doing plugs b/c they know of the high fail rate and the short $$$ cost..

http://catalog.eautopartscatalog.com/mercedesshop/sophio/image.jsp?title=Spark%20Plug%20Connector&url=http%3A//img.eautopartscatalog.com/live/F101084561BER.JPG
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  #9  
Old 06-28-2006, 09:33 PM
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Quote:
Originally Posted by Arthur Dalton
Just the coil ones ..
They are trapped in the heat by the coil being on top , along with their poor design of not having a snap type connector to the plug like the other 3 do. They use a spring pressure because the coil holds them in place on the plug. but the springs get heat fatiqued and fail.. very common fail part. The problem with these is when a plug connection fails , it can foul two plugs b/c of the waste spark series circuit. ..and then the ECU detects an ignition misfire and shuts down the signal to the HFMSFI injectors so the cat does not fill up with raw fuel.
So, a simple poor connector under the coil can cause the crappiest ruinning 104 you ever saw..
Any tech that works on 104 HFM will just change the connectors whenever doing plugs b/c they know of the high fail rate and the short $$$ cost..

http://catalog.eautopartscatalog.com/mercedesshop/sophio/image.jsp?title=Spark%20Plug%20Connector&url=http%3A//img.eautopartscatalog.com/live/F101084561BER.JPG

Arthur, forgive my continued questioning on this. Is it worthwhile for me to change the wiring to the other three plugs whiile I'm at it? The cost isn't trivial for the wiring, so I'm trying to understand if its worth doing? Your answer regarding the under-coil connectors is very enlightening and logical, no question I'll change those.
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  #10  
Old 06-28-2006, 10:15 PM
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Those wire have not been troublesome.. but , if you can see grayish tracking marks where they lay on the head in their routing paths, then I would change them.. otherwise , I would not.
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  #11  
Old 06-28-2006, 10:19 PM
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Quote:
Originally Posted by Arthur Dalton
Those wire have not been troublesome.. but , if you can see grayish tracking marks where they lay on the head in their routing paths, then I would change them.. otherwise , I would not.

Once again, my sincere appreciation for all this guidance...

I'll check the wires as you suggest.
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  #12  
Old 06-30-2006, 12:10 AM
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Quote:
Originally Posted by MyBenzMax
Once again, my sincere appreciation for all this guidance...

I'll check the wires as you suggest.
Ok, all work completed today...

1. Replaced Engine Harness
2. Replaced Plugs
3. Replace Plug Wires and Under-Coils-Connectors.
Car runs perfectly!

Question, when I removed plug from #5Cylinder(second from rear) it was oily.
It didn't appear fouled or any differment from the others, but is was definatly oily. Side note: I haven't noticed any oil consumption between changes. Actually no burning of oil. Should I be concerned over this plug being oily?
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1994 E320
2001 Corvette Coupe
1998 Jetta
1996 Camry
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  #13  
Old 06-30-2006, 12:42 AM
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Could be you're due for a new valve cover gasket. The set comes with six donuts that go around the spark plug wells. When they get old they can leak and allow oil into the spark plug well, which makes the plug look oily when you bring it up. New valve cover gasket is not that hard a job, treacherous with an old wiring harness, but you've got that out of the way.
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  #14  
Old 06-30-2006, 09:51 AM
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Quote:
Originally Posted by deanyel
Could be you're due for a new valve cover gasket. The set comes with six donuts that go around the spark plug wells. When they get old they can leak and allow oil into the spark plug well, which makes the plug look oily when you bring it up. New valve cover gasket is not that hard a job, treacherous with an old wiring harness, but you've got that out of the way.

Thats exactly what the plug looked like, oily when I brought it up. Is there a procedure for replacing the valve cover gasket? I mean, from the point where I have the plug&coil cover removed...what happens from there?

Thanks for optimistic guidance, I was worried it was a head gasket concern.
Appreciate your help...
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1994 E320
2001 Corvette Coupe
1998 Jetta
1996 Camry
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  #15  
Old 06-30-2006, 12:13 PM
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Removing the valve cover is pretty much self explainatory. There's six or eight bolts to come out, hit with a rubber mallot or something to break it loose and pry it up. Clean up both surfaces. It then goes back on dry but you may need a little silicone or something to hold the gaskets in place on the bottom of the valve cover as you put it back on. I don't have a torque number for the bolts handy but it's not very much.
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