Mercedes 220 CDi - losing power/speed at 80mph..
 

Hi,

Need some info/advice regarding an issue I have found on my new car. Recently traded in the old family mule, a Merc 200 Sport for a 55 reg Mercedes 220 CDi.

Car is in lovely condition, has 70k miles but only 2 owners and full history. I noticed the car developed an issue today, hadn't taken it out since getting it as I have been driving the scooby mostly.

Drives fine below 80 mph, everything works, cruise controls engages and disengages (thought it was the speed limiter on this at first). The autobox engages fine so don't think it's a drivetrain issue.

No fault codes are coming up on the dash and when I ran the diagnostics test it only reported that Service B was due in 2000 miles.

The Symptoms:

When driving at speed, accelerates fine, changes gears on time with no hesitation etc, turbo spools up fine from what I can hear under the noisy diesel however when it gets to around 80 mph it starts to feel like it's losing power or hesitating and struggles to get beyond 80 mph.

I wondered if it's not making boost however everything visually under the hood looks fine, the turbo looks okay and I can't see any leaks anywhere. Checked the air filter which looks clean as well (engine bay looks prestine).

I am not familiar with the diesel turbo engines on Merc's but reading a few posts on the net (not my model specifically) people have reported similar symptoms and put it down to the MAF/MAS being buggered.

I have 3 months warranty on the car so want to get a heads up on the problem so I can make sure the right things get replaced and the job is done properly as I don't want to drive 150 miles only to find the problem has returned.

Lol it's weird getting into the mule, I spent a few seconds trying to press the clutch only to remember it was the foot brake and I was in an auto. Then when the boost came on (torque is bloody nice on these Merc's) I was waiting for that head snapping power band and growl and then laughed and reminded myself I am not in the scooby :P

Thanks in advance,

Fz

check for splits on the boost pipes. check for splits on ends of vacuum tubes

Sounds like an AFM prob...Possibly the D cat starting to block up ?

Hello mate
I`ve had a couple of Merc cdi`s and it shouldn`t sound noisy. I had both C and E class from new and did about 60k in each of them and they were whisper quiet in the cabin and very quiet with the bonnet up.
I`d be looking at hoses:wonder: and making sure the fuel filter has been replaced.

Is it speed or revs related ? ie you lose power at 2750 revs no matter what gear your in, if so I would guess its the maf. Had something similar in my golf tdi.

Took it out today to have a proper drive, it feels like there is absolutely no power now, you can't feel the turbo at all i.e no pick up hence why it struggles to go beyond 80 mph.

I had a look at the pipework and can't see an issue however I don't think the turbo is working at all.

It may have gone intolimp home mode due to an engine fault.

If you have just bought it,go back to the garage and let them sort it for you..

Welcome to Mercedes ownership,the most troublesome car on the roads!!

Aye will do, got warranty on the car so going to use it. Yeah they are a bit temperemental, my old one was not too bad actually, as long as I maintained the extortionate servicing it was a happy car.

I was actually expecting the CDi to be a bit more reliable than the my old petrol one.

Lol my scooby is actually looking more reliable at the moment.

I also have same problem, do you know what is wrong with your car yet, i have taken off inlet manifold advised by merc mechanic to see if theres a problem with it, found nothing broken or leaking, feels like turbo not working when car is warm, also Ive changed MAF sensor still no difference.

Its cos its a diesel, very slow :D

seriously, my mate had a similar prob on a E320cdi, it was the pre-cat that had failed.

The kitten ? :Suspiciou

You sound like a BMW owner. I have had 3 Mercedes in the past couple of years. C220, E320 & now an ML320. All new vehicles, all covered apart from the ML over 60k. No issues on any of them apart from fuel pipes on the E & they were found & changed at service & charged to warranty.

ML is split new so not done much with this, my RR TDV8 was never out the dealers with lack of power & electrical gremlins.