I recently had encountered a very rough running engine after hard acceleration (high RPM), until the key was cycled, and then the engine would be smooth again.
SEE POST: C280 Poor Engine running after driving

Well I took the car to dealer for diagnosis... 3 days later, and 3 rental cars later, I got the belt tensioner SHOCK and BELT replaced for all of $70. I told them to change the shock along with diagnosing the problem. ANyway, they changed the belt without my approval, so I got it for basically free!
Anyway, they didn't get around to putting the car on the DINO to get a real good look at the rough running problem. Geez, they didn't even pull any codes!! But they suspect that the wiring harness would be a likely culprit. I guess it's never been replaced on my car, and I asked the service advisor to show me some of the wires... he did, and they didn't look too bad at all, even with squeezing them? I assume it's bad enough, since no wiring harness replacement showed up on the Vehicle Master Inquiry. I discussed with my service advisor the MB GOodwill policy. He said that Mercedes usually picked up ATLEAST 1/2 the cost. He said they even once picked up almost the entire cost for a 94 E320 with 118k miles. So that looks good.

Now I have a very quiet engine with the belt tensioner shock replaced (and BELT.... free ), but if you push it, I will get an extremely rough running engine (though doesn't feel as though it's going to stall, in the least. Runs like crap, but RUNS. I leave for Mammoth on Sunday... so lets hope the beauty holds out for my 375 mile trip each way! I guess I won't be doing too much passing (low RPMs!), a good thing I'm sure.

Ok my question: I have 110,000 miles on my car now... is it possible that the plug wires could be causing the misfire, which in turn, switches off the injectors? If it were the plug wires, wouldn't I have a rough idle most of the time? Does my problem seem like it's probably some random whatever wiring harness problem? Or is there anything else (could be in congruence with...) that might cause this? (car runs smooth once engine is turned off and then fired back up)

(First rental car was a Nissan Maxima... broke down on the fwy with 180 miles on it! Got a CE light and AT CHECK light! Called Enterprise, and they brought me a GMC Safari... what junk! So I went back to Fletcher Jones and got a BUICK Park Ave with leather, Auto Climate Control... WOW, what an interesting vehicle to have for a couple of days!!)

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

The most common problem in this engine is the ends on the coils. there are 3 coils and the ends will fail and cause a skip under load. I'd replace all 3 and the spark plugs.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

David,

There was a post by Pfphipps recently where he wound up replacing a coil. I believe it's the one with "error code 7" on it.

Joe

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joE
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"
http://banners.wunderground.com/bann...L/Key_West.gif

Donnie,
Have you found a preferred brand for replacement?
Thanks,
Arthur

The spark plugs, Bosch copper core.

The coil ends, OE.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Hmm, the coils. Glad I found an explanation. Maybe I will have them change the coils first. What does that usually run ($$)?
But if my wiring harness truly is deteriorated, should I have it changed... to take advantage of the MB $$ coverage?

Car drove just fine on the way up here... even with heavy engine loads... didnt' skip once. Are the coils less likely to act up in cooler ambient temps?

Thanks again!

(EDIT: Just did a search... what about fuel pressure or delivery? Since it seems to be fine until the engine is revved high?)

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Thank You...

One of the members recently posted a link (on TSBs?).... well I found out some cool info about my car (the engine)!

" *Light it up

The ignition part of the system is distributorless, and has some interesting features. To begin with, when it's below freezing out, it provides multiple sparks while cranking to get you fired up.

During an overheating emergency, timing is retarded under load to prevent internal engine damage. Engine speed, air mass, and coolant and intake air temp are all used to determine how much retard is prudent. This is not to be confused with the practice sometimes used in the distant past of advancing timing at idle to cool down combustion.

Speaking of overheating, to keep the cat from getting into that damaging syndrome injection is killed to any cylinder that's lost spark for any reason. Ergo, raw fuel won't get pumped into that catalytic furnace.

Primary connections carry over 400 V, enough to bite you. Make sure the core bracket is grounded. By the way, primary current is limited to seven amps, and the max secondary voltage is about 32 kV. As you probably know, the waste spark on the exhaust stroke requires very little energy, so most of the pop goes to the plug that's encountering compression.."

Wow, that's totally amazing! So I now think that the injectors turn off (IE, shutting off the cylinder(s) for the cylinder(s) that had the misfire. I am getting the codes read today, and I'll see if it's a random cylinder misfire, or a specific cylinder (or 2 specific ones ... =coil?), to get a better idea.

I have a $600 estimate to change the coils (parts [x 3 coils] & labor) from the MB dealer. DOes this sound like an expected
amount $$$ to change the coils on an M104 from the dealer?
THanks.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

I believe you are mis-reading Benzmacs post.
The common problem on 104 waste spark ignition system is not
bad coils, but the coil ends that connect the coil to the plug. There are these style end on the 3 plugs the coils sit over.
They are 8-10$$ each.
The other 3 have not been troublesome as they don't have the congested coil heat to contend with.
You will see them when you lift a coil. If you have spark related mis-fire codes, Try new ones before condemning your 3 coils.
As also said, change the plugs at the same time you are in there....
[ with copper, of course]

Good point on the "coil ends" or whatever you call the rubber boots. I saw my name in the post someplace and like you, it just started missing one day. I replaced the all the rubber boots at the time I replaced the coil. To be truthful, I suspected the coil I replaced was good and the rubber boots were to blame but since it ran great, I was not going back in to see which cured the problem. My boots were not helped by a small oil leak that got oil in the holes where the plugs are at. I think this coil end or boot has the radio noise suppression resistor in it and that might have been the problem. I suspect I now have a good running car now with a good extra coil.

As a side note, I just took the car in for emissions testing (2-3 months after the problem) and the hydrocarbons were 6 ppm (max allowed is 220 ppm) and CO was 0.00% (max allowed of .8% I think). Must be running pretty clean!

Well I went by the dealer today to have them plug into the STAR DIAGNOSIS machine. Well I got lucky... I asked my service advisor (young, real nice guy) if he could just hook it up real quick and pull the codes. Well they rolled the machine out, and plugged it into the CAN/BUS under the hood (I did not know that the OBDII info could be retrieved via this port! I learned that the OBDII connector under the hood was simply the 'generic connector' to meet the basic laws of OBD).

Well, I was hoping to get some sort of pattern, but didn't get anything that really helped....

Got codes:
P0300
P0302
P0303

So I'm assuming that these are cylinder 0 (?), 2, 3 misfires. Anyways, I decided to go in and buy the coil ends, as suggested. So I purchased 3 coil cable plug ends ($11.76 x 3), and I bought 6 spark plugs ($2.69 a peice). My spark plugs were changed about 35k miles ago (my service advisor told me that they're supposed to be replaced @ 15k intervals.... I thought I remember the intervals being 30k... I'll have to double check.) Well I was past due, in any event.
While there, I also bought a new wiper blade because the BOSCH blades sold at auto part stores do not fit properly (even though they are the right length and suppsoed to fit my C280). Well that blade mechanism was $36.40! Jeeez! I also bought some of the MB Grease (he gave me bearing grease?)... I'm going to lube my wiper mechanism.

I am going to have my independent mechanic replace the coil ends and spark plugs on Wednesday. This is a pretty basic service, correct? Just spark plug replacement and a few added minutes to replace the coil ends... correct?

(I really hope that this is the end to my LONG and PROGRESSIVE ACCELERATION RESISTANCE!

Thanks guys.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Why did you buy the whole blade? Unless there is something wrong with it (paint, rust) you can change the rubber insert.

Vin

Becuase I broke the blade the day before trying to put in a new insert that I had bought... I mean I pretty much mangled it.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

That'll do it.

Good luck with the coil ends.

Vin

I took my car over for spark plugs and coil end replacements today. Once he had a look, he told me that I would need new wires after all, he said they looked "arced" (sounds ARK). He also told me to get some new spark plug wire boots? I was in a big hurrey so I wasn't too clear on if those were the coil ends were not. Anyways, looks like I'm going to buy some wires tomorrow before... then finally have the beast prepared for driving again.

I'm guessing that my wires didn't last as long is because of higher engine running also. My car has probably had more engine revolutions, than the average.... in lieu mileage.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)