fasttommyv

Hey guys,

I'm having major engine issues in my cls55. Last night I took off from a light fast. (rolled into the throttle 1/2 way down in first and shifted at 5k rpm). After that, the cel started flashing. I could immeaditley tell it was running rough, at speed, and also at idle. I've got a p0300, p0303, p0304 p305 and p307.

So, where and how do I start troubleshooting? I have a pulley, tune, heat exchanger, air box and headers. The car has always run strong and I haven't noticed any loss in power or degredation of how it was running in the previous days. The only thing worth noting is that the belt is squeeking when the engine is cold, but goes away as the engine warms up. I have a month or 2 left with the cpo warranty, but am anxious on how the dealer will view this issue with the mods on the car.

Please help, and hopefully it isn't anything too catastrophic

Thanks,

Tom

desired_speeds

if I were you i'd take all mods off tomorrow then bring it to the dealer asap. What size pulley btw?

amg guy

iTrader: (1)

Did a quick search for you. Similar cases where the catalytic converters were clogged. P0300 is random cylinder misfire, p0303 is cylinder 3 misfire, p0304 is cylinder 4, p0305 is 5, and p0307 is 7.

Catalytic converters are covered for 8 years 80,000 miles from MB under warranty.

How many miles? Close to 100k?

BBBSS

Flashing CEL is a misfire as the codes indicate. You mentioned headers are your cats still in place? How many miles on the car? Any fuel upgrades? I'd pull the plugs out of cylinder 8 to be sure you didn't hurt the motor before firing it up again and possibly causing catastrophic failure. Look for any marks on the plug tips like something impacted the ground strap or the electrode tip etc. You have a descent number of mods and if you don't have fuel upgrades you may have hurt a piston.

ahmad0658

- Did you made quick check up over the engine?
- Have you had any smoke in any color yet?
- Check all plugs are tightened good enough.
- Check all plugs wires are in right contact
- Check the cats
- If your engine is fine after you finish checking up, I advise you to go and buy higher flow injectors before you do any more pulls, look for Bruce from TTM, he will be able to help you with that.

chawkins2001

Do you have any fueling upgrades, what was the outside temp, whose tune?

Cylinder Head

iTrader: (1)

Plugged cats for sure. Quickest way to wreck your motor.

bnzuovr

my cousin has a Ml55 02 model but he had a similar issue all 4 of his cats were melted and 2 2 rear ones were completely gone. Didn't think converters would do that to that car but that was the problem. So it looks like cats if you have them on there that is,if not i would strip it down put it back to stock take it to the dealer AND DELETE THIS THREAD IF YOU DO.

fasttommyv

Thanks for the replies guys. Few things:

I have a 180mm pulley.

Car has 66k miles.

It was probably about 60F when it happened.

It was night, so i couldnt tell if there was any smoke

No fueling mods. Couple questions about that. I have read threads regarding blown engines from the lack of fuel mods, but the ones that i have seen were all associated with long full throttle pulls, or bouncing off the rev limiter. given that i was only half throttle, and shifted at 5k, how could i have leaned out in that situation. I almost never push the car full throttle, and rarely go over 5500 rpm. I do plenty of half throttle, 5k rpm romps though...

3 things to note about the catalytic converters.

I bought the car modded, so am unsure what the stock configuration is, but i have 2 cats coming off of each side of the exhaust manifold.

A day before this happened, a friend was sitting behind me and i did a similar acceleration run out of the stop light. He mentioned that the exhaust smelled really "bad".

For the past 6 months i have had to drive it to work which is only 2 blocks away. (I know, i should walk, but quite frequently, i need the car to perform work duties) Could repeated cold starts/short trips make the cat failure more likely?

Finally, if it is the cat, is it as simple as replace it and all is good? Or can a plugged cat cause other major damage at this point...

Thanks again for the pointers,

Tom

Cylinder Head

iTrader: (1)

Replace and you could get away fine, but there is the chance you've done some damage to your plugs and hence cylinders if your cats have not been flowing. Mods are going to eat cats fast.

ETA: There is an open loop fuel rail FS at the moment by a fellow member, you should buy it.

fasttommyv

Your best guess, will the dealer do the work under warranty, (CPO or standard) or will they blame it on the mods?

BlkE55K

The more stock your car is, the better the chances are of getting the dealer to do the repair. You may want to ask around to see which dealers are more mod friendly.

fasttommyv

Thanks for the help guys. Im getting it towed to a trusted indy shop first to get get it diagnosed. I'll keep you updated when i find out whats going on.

Thanks Again,

Tom

TheVazha

Good luck Tom. Do keep us posted, I'm sure you'll get it worked out.

fasttommyv

Update, I had to start it up to get it on the tow truck, and it was running fine and smooth. So hopefully that rules out most of the major concerns. I should know more tomorrow.

Thanks again,

Tom

hbr

Good news bro........fingers crossed for ya

fasttommyv

Good News. The shop diagnosed it and it is bad gaskets on the supercharger manifold and surge tanks. I cant complain about that. Thanks again for all the input.

grantwoodtx

WOW good news that it's nothing major!

Roverron

It's about time someone comes back with a good story from a horrible feeling.

fasttommyv

Hey just an update. I got to give serge from benzworks major props. He troubleshot the issues on the car, and then was able to coordinate the repairs with the dealer, and get all necessary repairs done under the CPO warranty! He had great customer service and went above and beyond and saved me tons of money and headaches with trying to get the car fixed under the CPO with mods. serge has a customer for life!

For the record, The dealer also found a bad injector as well, so hopefully this thread helps anyone else who is having similar problems