Thank you for the quick reply, NRL. Yes. First cold start in the morning. Upon the second fill-up while still in Texas I added a bottle of gasoline dryer. The second fill-up was injector cleaner. The third was Techtron. Every morning while leaving the cheap motels was about the same thing for the first mile. I've been home for a month now and have filled the car twice. Yesterday I added STP gasoline treatment. For decades I've run all of our cars and bikes on the same crappy gasoline from the Mom&Pops just around the corner with no problems. Of course I will continue to monitor the situation with the idea buried deep within the back of my mind that perhaps a visit to our local fix-it shop might be in order.

'Cheers' Roadslayer

 

Don't know why I didn't see this before, but this is wrong. When a misfire is sensed the fuel is shut-off to that cyl, that is why I was able to shut-off and back and it would be fine for a while, the fuel to that cyl was reset.

 

If your getting a misfire, it will throw a code, no Check Engine light and your probably just looking at a cold engine, new plugs might not be a bad idea if you don't have records showing recent replacement, but at 14K miles, not sure I'd even bother. My SL600 and my wifes E550 both run a little rough for the first mile or so when cold.

 

While paying a visit to the dealer in Austin because of the check engine light he pointed out to me how to detect a miss, assuming I don't drive around with a full shop of Mercedes-Benz diagnostic equipment in my trunk. Open the drivers door and place your hand on the top of the door sill. It 'should' be perfectly smooth. A miss, and it was, can be felt with the discriminating hand. I was told the check engine light might clear itself on my trip back to Seattle. It did. However, at the first morning start up I'm always greeted with what I think is a misfire for about the first mile. Kind of a grumbly grony feel like I'm on a gravel road. Then all is well. Hell, my $200 Oldsmobile runs better than this.

'Cheers' Roadslayer

 

Did they happen to tell you what the code was for the Check Engine light??

They light will go away after the "issue" hasn't happened for a couple starts, but they remain as historic codes that can be read. First time it senses the misfires (or other issue) again though the Check Engine comes right back on.

 

I don't remember if he told me the code. I was told I could schedule it in for further diagnostics. Looking back I could've. Should've. But didn't. No more check engine light and no malfunctions on the display.

Thanks. Roadslayer

 

Mine seems to run a bit rough on idle in the cold weather... going to scan it out.

 

Believe it or not after 4000 quick miles I'm still in the test mode. After letting it warm up the other morning and running fine(knock on wood) after that for a couple of days I dare say it might not be missing as much, or at all on first morning cold start. Today the weather is typically Pacific NW horrendous and I'm not inclined to venture out with a mostly clean black car. That duty shall remain with my $200.00 Oldsmobile.
One more thing I notice is the temperature gauge begins to rise in moments of cold start-up. I mean like two minutes. Or the first thousand feet. All of my other cars start warming up at the same spot by the lake. Or about a mile and a half. Or maybe 5 or six minutes. Just a bit of trivia I'll throw out.

 

On my 2005 SL 65 with 40K miles I checked the following:

Cat - ok
Crank position sensor - ok
MAP sensors - ok
Coil packs - ok

Plugs - changed - 5 years old and should be changed regardless miles (manual)
Misfires returned after a day....then I checked the Ignition module....BINGO

Ignition module - replaced....this was the real culprit.....
Intercooler air temp motor replaced...
covered under warranty - $ 1,100 part.......no issues since.....

I got the gas excuses etc........not the case.....highly rare these days....as engine adjusts, etc...

 

Was the misfire on random cylinders or on a specific side of the motor? That's usually a good way to tell whether it's the ignition module or a coil pack.

 

Misfires were on one side only.......7-12 cylinders....

Which lead me to coil pack inspection first, then plugs - which were fouled on one side, then Map sensors, then Crank positioning sensor, then cat.....but it was the ignition module that was the ONLY issue......coil packs were fine and have been now for last 4,000 miles, etc....

Based on the forums and their information on misfiring, I would have bet coil packs, but not the case....

 

Interesting, thanks for the great information.

I have a spare ignition module I may try out... right now I misfire on the passenger side above 4K RPM and while under boost.

Same story as always... CEL, limp mode, restart, back to 12.

 

I was baffled for about a week until switching the module.....hope that cures it....

 

Another method that I've used... I hook up the Star Diag and watch the error rate/per cylinder graph and see which ones collect the most errors. Then replace components and run the same test, see if errors are still being collected.

 

Thats cheating...

Actually, I'm just jealous, I need an SDS......

 

...for this thread.

I purchased my 06 s65 last year and had cylinder misfires on both sides after a hard drive following an ECU flash. Replaced both coil packs from "for Mercedes" rebuilt...crap. GUY (MARCO) IS A SCAMMER DO NOT BUY ANYTHING FROM FLORIDA NO REBUILT COIL PACKS>>>STILL OWES ME FOR THEM.>>Changed his company name to dodge bills. Sorry for the tangent but I am pissed!! I ended up purchasing new packs from him and sending his rebuilt crap back...It has been a year and have not received a refund for the first set as I foolishly paid for the new set before returning the rebuilt...I now have only one side misfiring as dictated by logged codes.

Background: I drive the car at minimum 140mph daily and weekly hit 160...fastest around 180...things get passing by quick at those speeds so usually I look at exact speeds until slowing. Point is I drive the car HARD...or as I feel it was meant to be driven.

My misfires happen when warmed up consequently shutting down a few cylinders and running like a honda civc. At first they could be fixed by turning car off and back on. Now the car will not respond like this. I am trying desperately to get the damn receipt from this guy to exercise the MB parts warranty which my mechanic suspects to be 2 years.

It has been suggested to check the voltage regulator as a possible cause. The issue seems to be related to some sort of heat soak...Car will run fine 0 misfires hauling serious *** with full power...but when I turn it off to grab a drink from a store...BAM runs like crap upon startup.

Question is could a set of coil packs really go out after 20k mi of hard driving ?

How do I tell my mechanic to test the ignition control module? He already said he does not have a spare. I would just change the coil pack but am complaining daily at the scammer to find my purchase receipt. I feel like flying to FL and paying a crack head to super soaker his lot of cars with Tolulene or Acetone... DO NOT BUY REBUILT COIL PACKS OR ANYTHING FROM FOR MERCEDES OR A GUY NAMED MARCO in FL.


From reading could be;

Coil pack
Voltage Reg. <---could this heat soak?
ICM <---could this heat soak?
Clogged Cats??
Spark Plugs? <----Probably not because I have power until heat soak

Just got the car from the shop after a radiator replacement. New front shocks and ball joints a month ago, new rotors and pads the month before.....she is a shop ***** but I love her.

Sorry to ramble. I am a bit frustrated at the moment any help would be greatly appreciated.

 

Is that in DAS?
Where is that graph? How much data does it have, real time only?
I have DAS but not an expert.
I'm trying to find out my CEL po300 random misfire issue is, but it happens only when I gun it to WOT. I'm thinking CPS or ignition control module.
Is swapping coils the first recommendation?
I want just start with ignition control module, looking it up on how easy compared to the other paths.. anyone with the part#?

 

It's back after 2,500 miles after full throttle acceleration..

Misfire on cylinders 11,12....same as before after replacing ignition module, intercooler air temp motor, cracked map sensor and 24 plugs........

Dealer will replace associated coil pack this week.......another $ 1,850 or so for warranty and just had front strut done yesterday......for 1,193.........warranty company getting gruff with dealer/indie shops now.....I have now claimed close to what the warranty cost me.......$ 3,900 was the warranty cost to 60,000 miles, car has 44K......1.5 years left on warranty......hopefully this coil pack does it for good........

 

Think the ICU/voltage reg part number is 0001500258

Let me know if anyone has a good used one. Trying that next after replaced one coil pack...problems persist. Dealer wants $800.00

 

I bought the ICU/Volatage reg (0001500258) at parts.com for about ~$600 and change.
I have yet to have swapped it but today I had misfire codes after I gunned it it today, the code came up after a few minutes later; almost like a heat soak caused either that part to overheat or the right coil pack overheated.
All the CEL codes point to the right ignition coil (passenger side)..

So, I'll swap it out tonight since it's quite easy compared to the coils and see what happens.

Ordering the right ignition coil with spark plugs next.. might as well.

 

ugghhh I am the new culprit. I get a CEL and code po303 consistently when I do pulls its misfiring on cylinder 3. It recently came on soon after start up and just putting around town. But it will always come on during a pull and throw a CEL. I don't get any other code (yet). What could this be, the coil pack? Also where did you guys buy your spark plugs, dealer or online store?

 

My driver side coil pack will be replaced bringing the cost of the following for this misfire issue adventure on my 44k mile car - and 3 trips to the shop......to......

$ 1,900 - Intercooler air temp motor/ignition module
$ 1,850 - coil pack
$ 150 - Map sensor
$ 450 - new plugs

$ 4,200 approx. for the "supposed" cure.........it is only money

 

Looks like I'll have to pay to play... one brand new coil pack on its way.

I did find out in my case that the first owner (I'm second) had a coil pack replaced at 40k.
Left side. So to start off before replacing anything , I checked the part#s on both the coils and one of them has got the new partno and the other the older part#.

So the bad side is the right side, checked that part# and it's the old part#, so I'm thinking the right side finally went or is on it's way.

The old Part#'s that are known to go bad are:
A275 150 04 80 For the R/H side and A275 150 05 80 for the L/H.

The new Part#'s are:
A275 150 06 80 for the right and A275 150 07 80 for the left.

So check em' numbers and if you can post them.. Easy to spot with a flash light, find the coil, follow the length of the coil and you'll see the part# sticker on the end toward the rear of the engine where it sits.

Curious to see who has which part# for left and right side (even though you got a replacement put in) and it still misfires..at boost, heat soak and never at idle.

 

Mine was intially random, but only when I gunned it..

The last two CEL episodes were all pointing to the right side.. So I think the right coil pack finally is bad..

The new P/N`s are:
A275 150 06 80 for the right and A275 150 07 80 for the left.


I swapped out the ignition transformer, really easy.
Went for a drive and it errored all on the right side(again) so it looks like the old coil pack (the one with the older one partno#) hopefully is bad.. new coil pack on the way.

I'm a DIYer so I'll take my time in the garage swaping out the right coil first and probably check a few spark plugs before I put new ones in.

I'm thinking this is not going to be the only time I'll be swapping out the coils.


I saw the write up on a DIYer coil replacement, but I'm at step one, trying to remove that connector off the air box and the air box itself..
Wish there was a video on it..

 

Please don't be stuck at trying to remove the air box.