-Elliot-

Hello, I love my 2001 clk320 auto and had an initial 18months very trouble free ownership. Unfortunately that has changed and despite my efforts and my money the mechanics here in spain are not very good and i'm in need of help.

It started a few months ago when driving spiritidly the car kind of stuttered and the engine light came on. I got home and and had the following error codes:
P0105 map sensor
P0300 random/multiple misfire
P0306 cylinder 6 misfire

I cleared the codes but the map sensor would always come back next time I drove.

It went to 3 mechanics who all said the car was working petfectly. The first 2 cleared the code and said there's nothing else they can do. The whole time the car drove fine. The 3rd mechanic held on to the car for nearly 2 months in the end, always promising the next day and then the next day etc. He said it was a bad sensor but didn't know which one. I took it to another mechanic and got him to change the spark plugs (there was no record of these being changed in the history), and the car ran great, no error codes and all was well again. I had new battery fitted a few weeks ago and have done a couple of long journeys with no problems.

However just now, I floored it to overtake, the car kicked down and flew but shortly after that it started to lose power. I was accelerating and the revs went up but didn't translate to power. Pulled over turned it off, started it up again and it was fine. Drove another mile maybe and same thing lost power, wouldn't accelerate lost speed - I just managed to pull over somewhere safe the car stalled and the engine light came on. I felt crushed 😞 I did think I could smell like a burnt clutch smell but not sure if that was me or not.

Luckily I had my code reader - I didn't save the codes unfortunately or take a picture but they were misfire multiple, misfire cylinder 4 and misfire cylinder 6. I cleared the codes and cautiously drove 20km home with out issue. The car drives fine, if I rev it it sounds great, the engine light didn't come back on and there are no new codes there or pending.

So where on earth do I start? is it just coincidence that I've had problems when giving it some?

The car is well serviced, the first thing i did was get mercedes to service the gearbox. The car has 190k km so about 112k miles

Sorry for the very long post just trying to give as much info as possible.

Thank you for your time

jstrider

I recommend checking the coils on the cylinders throwing codes. It may be time to replace them all.

2MERKS

I would agree, also view the videos on youtube to get some idea what/how to sort out those problems. GL
R,
2Merks

DeLasse

did you figure this out? Not sure if the crank position sensor could be ONE of several issues you are having here, which you are definitely having... as the spark plugs should have been replaced etc

whats the temperature gauge look like after the spirited driving?

-Elliot-

No further really with this unfortunately - it's at another workshop now but I'm not expecting much different.

I've been driving the car cautiously in Winter mode and it's been fine with no error codes stored or pending. The engine sounds lovely, the gear changes are fine. I've done a lot of Internet searching and I did a thread about very similar sounding issues and it turned out to be the "pedal value sensor". The problem is though its a slippery slope just replacing parts without a proper diagnosis. The pedal value sensor is €200, new coils and leads €250, new crank sensor €60 and I could change all those and still be in the same place.

The gearbox service was the very first thing I had done. That clutch smell has worried me but I'm not 100% sure it was me or if it was from the passing wagons. Temperature gauge when booting it was normal (for info it had a new water pump and thermostat and aux belt a year ago).

So not really sure what to do at the moment

DeLasse

can you change the coil out on cylinder 6 yourself? just make sure you got the right cylinder and go for it. Whatever you did driving your car may have caused some burning of the clutch, but if it is shifting fine you may have 0 transmission related issues.

if you are beating on the car I would recommend properly flushing the transmission fluid every 30-40k. Hope the transmission was flushed and the fluid wasn't simply just changed out. You want to cycle and dump fresh fluid to clear it out.

is it accelerating normally again since clearing the codes?

-Elliot-

Thanks for the response 👍

I'll look at replacing the coil but I was under the impression you had to replace all at the same time? Or its best practice at least. Any brands to recommend or avoid? Hella and bremi are €40 on autodoc, meyle febi bosch beru etc are €60-€70.

Im not thrashing it round or anything just flooring it every now and then so it kicks down and that's what it doesn't seem to like (or that's just a coincidence)

I've been driving it cautiously in Winter mode and its accelerating and shifting as i'd expect - and no error codes. With regards to gearbox flush I've no idea - a mercedes main dealer did it so whatever the standard procedure is I guess. I'll look into a proper flush if I ever get this issue sorted.

I'll update this week when i get it back from the current workshop

DeLasse

A few things here, these cars are associated with --OK-- transmission reliability with the pre-shift models being reportedly somewhat less reliable, so it's good you have an 01. The trans fluid interval is 40k on the 722.6, and I'd lower that if you drive aggressively. I think by design, hardshifting the car the way these transmissions do can be pretty demanding on them. I'm almost unfamiliar with automatic transmissions in 35 years, so I can't say if other models have responded to the gas pedal quite the way these MB transmissions do, but I'll say this.. I've not once felt comfortable giving it a lot of gas with a turn in sight. No way in hell. It's way too unpredictable, at least for me. Straight line only.

Although the car typically doesn't engine brake very much, I still try and downshift to the majority of stops, it's just rare I get a 'complete efficiency' stop, downshifting to idle. This process obviously engages the transmission at higher rpms, but reduces some brake wear. Because of this, I'm intending on flushing my trans in better weather. At barely 42k, I doubt it's been done, and doing so will allow me to use the shifter and drive the car as I like without worrying about the gearbox.

The coil should not be a big deal and probably only requires a screwdriver and something like a 10mm socket. Me personally, I'm not going to change a coil unless I have an ignition malfunction, but having an extra coil on hand isn't a bad idea. If Hellas still a german part that's probably just fine. I'd just make sure you're changing out the right cylinder that has the code and you'll have eliminated one potential issue.

DeLasse

i looked into flushing the transmission and indeed a lot of people will recommend doing it in incomplete ways, but there is a formal method of flushing it which I did a couple years back on my Volvo. Otherwise you're leaving a lot of the bad stuff in the system.

info with a link here:
https://www.benzworld.org/threads/tr...722-6.3052827/

-Elliot-

Many thanks for the help DeLasse 👍

The garage has just contacted me....a little is lost in translation but they said they concluded that there were 2 faults - failure of ignition coils 4 and 6 and a fault with the flow meter. I did ask for a quote first but they've already changed the parts saying they needed to test that it was resolved on the computer. So not thrilled and think it's too expensive at nearly €500 but it's done now and hopefully it's fixed. Will update when I get the car back. On a positive they've done a pre ITV test (annual road worthiness test) and they said its good and will pass no problem so that's something at least

DeLasse

good! hopefully that worked out any kinks