I'll check that, too. Thanks


meanwhile I thinmk I will replace the 3 spark plug connectors that go to the coils. These have not been replaced ( they have M/B logos on them), even though I had the wires and plugs changed. If one of these connectors was faulty would it cause misifiring and skipping?

Coil to plug connectorsa are the FIRST misfire suspect on 104 HFM/SFI engines...by far...

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A Dalton

I noticed that clamp- it's in a tough spot to get at.


Do you know of any good way to test spark plug to coil connectors and also the coils themselves ( i.e. volt/ohmeter, etc.)?

I can't keep buying parts and trying them out.. Thanks

The proper diagnosis is done with a secondary waveform from a Scope ..
But, most DIY do not have that equipment.
So, we tell them to change the coil to plug connectors under each coil as they are notorious for misfire and should be done as general maint.
Most Techs just change them when they do plugs b/c of their known misfire cuases.
Also, these systems don't like Plats at all, so consider the correct plugs.
If your plug connectors are old, I would just do them..at $4.00+ for gas,
you certainly need a well running engine..............

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A Dalton

Thanks.

I just took the car out to runb a couple of local errands- maybe drove it for 10 miles or so. Guess what? No misfiring at all ! I swear these cars are possessed, or at least intermittently occupied by gremlins who delight in messing with us......

The problem is intermittant b/c of the type connection to the plugs from the connectors. Those 3 do not Snap onto the plug like the open ones do..they
are a compression spring and it is the coils placement that holds them down.
If you take one out, the thing to look for is the connection inside the connector that goes on top of the plug..if you see these are grayish colored , they have been arching and it is time to replace them..they take a beating b/c of this poor design in the connection and they are trapped in engine heat b/c of the coil on top , where the others are open to some breathing and heat dissipation..which is why they do not have the fail rate as the coil ones ..so , that's about it...a maint. item, just like the plugs.
One wants to remember that a coil fires TWO plugs on this type Waste Spark DIS system, so if the coil connector fails, the next plug is in series with that one so the misfire is amplified...along with the fact that the ECU is programmed to cut fuel to the injectors everytime it sees a misfire..so, no gas..compounding the skip....
See why we change them????
I would also check and see if you have the old part# OVP...that is ECU feed and a common intermittant problem..if it is the old #, chage it regardless or you will just get stuck when you don't want to be.

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A Dalton

Yeah, with a SCOPE.
We are simply telling you the most possible suspects, according to experience and your complaint.
If you want a definitive diagnosis, buy a DSO Scope and it will tell you exactly what the ECU is seeing.

But you are a DIYer, so DIY info is :

Misfire on your car is commonly 3 plug connectors , OVP, wire harness , or incorrect plugs.
The connectors and OVP are not big $$$ and both are maint items anyway, so you are not throwing parts at it................ I always start with looking at the plug connectors and checking the OVP part #.

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A Dalton

That would be the Over Voltage Protection relay, correct? I read about that in an earlier post....

this confirms my theory that once you open a can of worms, you need a much bigger can to put them all back in



thanks again

Yeah..
Do a Search on "OVP" and another on "Plug Connectors" and you will have enough info to fill a NY City phone book.
Mainly b/c, as I told you..they are Infamous for misfire failures..

..and your OVP had so much trouble that they Modified it and went with a different manufacturer to remedy the ongoing problem....so, why don't you just look and see if you have the old part# on your OVP..it is that simple.
..or, go and have a Dealer Scope it out for you. That will prob cost about 5 times what the connectors will ......

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A Dalton

Where is the OVP physically located and what does it look like?


you should charge people (like me) for picking your brain.....

No , No charge...Free advice..so re-read it.
I just told you to use the Search Function for "OVP" .
And you come back with "Where is the OVP? "
You didn't read a word I said...
Do you want me to type all the OVP info that is already right at your keyboard ???

ALL the OVP related info in the WORLD is in the Archieves ...how else can I get this message to you ???

You want the part #'s... they are right there on your keyboard.......
Do you see the 'SEARCH" function on the top of the page??
Go here:

How do I Search for information?


http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2EI1B4MYE2FF0U74DI&yearid=1996%40%401996&makeid=MB%40%40MB%40%40X&modelid=C%2D280%2D001%40%40C+280+Sedan&catid=P%40%40Body+Electrical&mode=PA&subcatid=P2056@@Overload+Relay&source=www.peachparts.com&clientid=catalog.mercedesshop

I'm Done.

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A Dalton