Of course ..it is a Waste Spark DIS system. They are in series and one fires on Event stroke and one fires on Waste stroke. That is how you can run 6 cylinders on 3 coils...they fire two cylinders at once, but b/c one is firing on the Exhaust stroke, it is a WASTED SPARK and means nothing.
My concern now is do you have fire at the plug under the coil...
A test is to lift that coil ad use a plug wire in place of the Plug Connector [ what you call post/boot] and see if that has spark.

But don't disconnect the other in series plug.

..or, you can swap the coil with another and see if the misfire moves with the coil.

If you have no spark under the coil along with 5, then you have a bad trigger circuit in the HFM control module or a broken sensor magnet on the flywheel. There are 3 segments on the FW, one for each coil.

test that plug under the coil.

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A Dalton

Ok. But like I said earlier, code that mechanic pulled said misfire on #5 and the car drives fairly well; reached 70 ok. 'shudder' in car from take off gets better as speed increases but never fully goes away.

Thanks again for the help. Not a lot of folks near me that knows the car well.

Which indicates possible ECU trigger/weak spark.
So.............. lets see what we have under the coil ..ok?

Unless you have a DSO Scope??????????


..and, do you have Plats ?

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A Dalton

Sure. There is always a possibility what I got from the store is bad. Kind of like buying a cell phone; eventually you'll get one that works.

Gosh, no, don't have a DSO scope, but would love to add to my gadget garage.

If we're talking about an ECU failure, then I'm leaning toward the wiring harness not being replaced or that the 'new' one has worn out...but I'm going to think positive that there is still an issue between the coil and the plug.

I'll dig into it tomorrow and let you know what I find out. Have a good night.

Yeah , a DSO make these jobs a 5 min experience..

Anyway, if you are familiar with the codes from the Diagnostic box over by the battery, you may want to go into the ECU at pin 8 and see what it has detected as far as the coils are concerned..that would show up as a code 22 there. You can also test for V coming into the coils primary [12v] to test the harness. There is always 12v HOT at each coil w/key ON b/c the switching is done by the ECU on the ground side of the circuit, so I would check that you have coil primary power. [ simple test lamp]


E320 16 PIN DTC Charts inc. pin 8, pin 14

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A Dalton

Cool. Thanks. Saw your previous posts (in another thread) about the codes LED kit and have the diagram printed out. Radio Shack (and when I was a kid in Chicago Olson Electronics) is a favorite place of mine.

In response to the plats, here is exactly what I ordered:

3 0001593642 Spark Plug Connector; Coil to Spark Plug
1 00119 Ignition Coil
1 09385 Spark Plug Wire Set; OE Type; 3 Wires Only
6 F8DC4 Spark Plug; Copper; Standard Electrode; OE Plug

Pretty sure I'm on the right track with the parts I ordered, just had gone as far as the search engines and my knowledge could take me.

Yeah..that's all cool, even the right plugs.

get to that pin 8... and just for kicks, swap out that plug wire from another coil over to 5, just in case you have a bad wire...that is what it is starting to look like. [ or weak coil]

See ya

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A Dalton

In support of what Arthur is saying, I have had a similar experience.

A single-plug misfire, replaced plugs, no change. Ordered new wire set and 1 new coil, didn't need the coil, it was one of the wires.

Seems odd that a bad wire (or one bad plug connector) would affect only one plug when there are two in series, but it is exactly how it worked for me. It ran as yours does: idled on 5cylinders, but easily made highway speed on 5, just a vibration at lower RPM, but never seemed to fire on all 6 (the engine management will cut injection to the misfiring cylinder so it doesn't get a second chance anyway, ... does save the CATs from damage though).

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Gone to the dark side

- Jeff

Went back to what you were saying - even though I was thinking 'what are the chances I received a 'new' but defective coil'...but that may be what we have here.

I moved the 'new' coil with its' new 'spark plug connector' from the top of spark plug on cylinder #2 to the top of spark plug on cylinder #4. Now I get no spark on the spark plug for cylinder #3!

So do I need to RMA my coil? (I had extra new 'spark plug connectors' that I tried swapping out but still no spark).

Thanks.

I wasn't disagreeing with Arthur, primary problem was terminology. Second problem was me not believing I could have received defective parts. But as you can see in my response to Arthur's last posting, moving the coil to a different cylinder pair did result in a 'no spark' on the other cylinder. So the problem moved with the coil, indicating that one of the new parts is broken, and I'm leaning toward the coil being damaged since boot has been replaced multiple times.

I work in technology so I completely understand broken new parts and confusing terminology. Hopefully it can still benefit someone else to know that just because the part is new doesn't mean it is going to work.

Just for the heck of it I put the old coil with a new spark plug connector back on and the car runs like a champ. So old problem was bad boot, new problem was bad coil....or I accidentally put the old coil back on to begin with.

Please forgive.

That's why we always swap coils w/o swapping the connector and watch to see if the fault follows the coil to isolate the problem before condemning the coil.

Surpised your guy did not do that.

You also mentioned the new coil came with the connector...that was suspect to me b/c they do not come w/connector..unless someone returned it and they just shoved it back in a box and resold it to you...who knows ????

Anyway, 90% of 104 DIS ignition system misfires are the Plug connector/resistors under the coils..they crap cuz they are heat fatiqued cuz they are trapped under a hot coil and have a poor plug connector design ............Any benz Tech will simply change them when doing a plug change bc they are aware of their frequent failure rate.

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A Dalton

Yeah, but more and more I believe I was doing the typical diagnostic process:

1. Replace plugs
2. Replace wires
3. replace spark plug connectors (but not coil)
*got interrupted*
4. went back to project thinking I had already replaced the coil and started the car and it was still missing.

I say this because when I took a closer look at the coil I *thought* was the original/and had already removed it had a flat top, whereas all the coils on the engine had triangle look to it (like the roof of a house). The suspect coil that was on the engine during the misfire had a different part number than the other two coils and that threw me off the trail; I thought it was the new coil. Just glad I went back to the supposed 'old/defective' coil and checked it. Car runs like it is brand new now.

Glad I found this forum and thank you for insisting on double checking my work.

Well, ya did real good................

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A Dalton

I didn't take it that way, just offering my experience with this counter-intuitive symptom where a connector in a series system could affect one of the two series plugs, ... still don't get it but I do keep a spare coil, wire set (6pcs), and OVP around for the 104s.

Didn't make sense to me but it worked. Not the first time.

Happy it's running smooth now.

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Gone to the dark side

- Jeff