170 cdi power loss

[Raincheck]

Hi all,

I have a 2003 A170 CDI suddenly i cant get above the 3000 rpm and the top speed is now 100 kmh. It still runs fine in the city but on the motorway i cant speed up. 8 months ago it had a big service and a belt change.

I found one post with the same issue but no answer in that.

Help is more than welcome.

Grtx Rick

[gdlm]

Had exact same problem last night (and about a month ago).
Local dealer was no help .. oh bring it in.. sounds like an ECU problem.
Yeah, right (earlier posting on this problem ended up with the guy having three new ECUs and the problem still came back.)
What I have found is that if you turn off the engine and leave it for 10 mins then restart then it is OK.
MB customer service said if this occurs call the MB breakdown centre and they may give some help additional to driving to nearest dealership?
It can be dangerous as you can be overtaking when this problem cuts in and that can give some unexpected challenges.
If others who have had the problem and actually fixed it then please post something!!

[micksear]

I have the same problem. OK, the power has never been good, but I've just had the clutch replaced (ouch) at 80,000 miles and suddenly I can't get over 3000 revs either (and it takes a while to get that far). Can't get above 70 mph on the road. This is dangerous! I can't pull out into moving traffic because they'll just go right up the back of me.

Does anyone have an answer for this? I expect the ECU has reset since the battery would have been off for some time when the clutch was replaced.

[TonyH]

Hi folks, I've had exactly the same problem. With some searching I found this:
http://www.benzworld.org/forums/w203...ml#post2612497
I've tried the fix suggested, when flooring the pedal for 5 seconds something went clicky behind the dash & the oil light came on. Driving to work & back it seemed better, but I haven't really pushed it yet.

[billythesquid]

Did anyone ever find a solution to this issue i have been tryiong to resolve exactly the same on the wife 2000 a170

driving me nuts to be honest.

been a mechanic for 15 years and i`ve tried all i can think of any the annoying thing is nobody has a clue.

if you have resolved this issue please post it up

Many tahnks Tony

[KRMOTO]

I have had this problem and found that if l ran the car untill the engine is warm then stop and restart it was fine, also try stop then lock doors (with key fob)then unlock, I know it sounds a bit mad but it has worked for me.
good luck.

[m4ttyb]

Hi, I have had this same problem recently, it resembles a similar problem with a Passat TDi I had. Turned out to be the Air Flow Sensor/ Air Mass Meter, whatever you want to call them.
I removed mine and cleaned it with some 'electrical contact cleaner' from Screwfix, item number 41990 and popped it back in. Mine is working as it used to now.
Maybe it will work for you too???
Cheers Matt.

[bigiqi]

hi guys, i have a problem with my car was wondering if anybody out there could give me a solution please. ok my car is a c200 cdi on a 05 reg. a few days back i started to have a problem with the fuses. each time i went to start the car the fuse would pop the fuse was a 15 amp after blowing 5 i replaced it with a 30 amp fuse it has not blown that but i cannot start the car sometimes. i turn the key and nothing then if i leave it for about 20mins or so it will start but then when i drive the car after 15mins of driving i start to lose power and the car will not go over 3000rpm. anybody out there that can help me please?

[deluded]

First post and all that

Just been researching this exact problem for my missus, who has a 1999 A170, and google pointed me here

The problem has been intermittent for around a month now and is progressivly getting worse Only seems to kick in once the car is fully warmed up and under load (motorway driving etc). It's as if the car gets to a certain temp and decides its going into limp home mode and drops the limiter & boost. I dont know if there is any such mode on the ECU though.

Also, I noticed that when its having this problem, the turbo doesn't appear to be spooling, or atleast, it is, but there is no pressure. The turbo fails to make the signature whistling noise when the problem is occuring. Is there some kind of pressure bypass valve? Could the wastegate on the tub be stuck?

Also, seems fine once you have turned the car off and restarted after about 10 mins. To me, this points to an ECU error (eg. limp home mode), Although we are not getting any error lights on the dash to point towards this.

Just seems strange that noone seems to know what this could be. I haven't really had a chance to have a look at the car or test any theories. I will try the ECU reset tonight and see what happens

Any other help or advice would be appreciated

edit : please note, I know very little about turbo diesel cars! I'm a petrol man myself, so if any of the above (with regards to wastegates etc.) is nonsence, feel free to correct me!

[deluded]

hello again.

Thought I should post my progress.

I did a bit more research and found that some other Merc diesels had the same problem with the owners replacing or cleaning the MAF sensor. I decided I would give it a go.

Went to a local motor factors and got some Holts Electrical contact cleaner (£4.99). Went to halfords and got a security torx key set to unbolt the MAF sensor (£9.85). Unbolted it to find the sensor covered in a layer of black crap. All in the recesses and all over the contacts. obviously, 90k miles and filter not changed in atleast 35k (blame the missus ) hasn't done it any good.

Got a few cotton buds and with the contact cleaner in hand, set to work cleaning it up. Sprayed the cleaner over the lot, let it soak for about 20 seconds and began to clean up the contacts and bare metal areas, as well as all of the plastic parts. Also spayed the cleaner into all of the recesses and tried my best to clean out all of the black crap from inside them.

Got it looking good as new and popped it back in.

The car has been transformed! Pulls far better than it ever has and as of yet, has not lost power again. Revs clean upto the 4.5k limit and pulls like a train. Ive done about 20 miles in it since cleaning it and it hasnt lost power again so far where as yesterday, it would do it on every drive after a few miles.

The missus is off to manchester tomorrow so fingers crossed, the power loss wont come back!

So just to say really, anyone that has this problem, pop the MAF out, give it a good clean with contact cleaner and go from there! Seems silly to replace a fine MAF for a £160 new one when all it needs is a bit of a clean. Worth a go first anyway.

It also makes sense as to why the error light never comes on. Sensor is perfectly fine. Not faulty in anyway, its just that the ECU will be getting wrong readings and so shuts itself down into limp home mode but doesnt display the light as nothing is actually broken.