First engine problem with the S204.

[AMGeed]

So after just over two years of ownership, I have the first problem with the engine. (2009 S204 180k with M271 engine)
Parked up last Fri evening after a non fault drive. Started today and pulling out into traffic I noticed a distinct lack of acceleration,
Coming to a halt in traffic, the revs were fluctuating between 500 and 1k rpm and taking the foot off the brake it was jerking as it crept forward.
Deciding all was not well I turned to return home and on pressing the throttle, the revs rose but there was no power at all and the engine noise increased considerably.
On the 3 mile trip, fuel economy dropped to 15mpg. I'm guessing my first experience of limp mode?
No CEL , no black smoke I could see and no fault codes on my cheap code reader though that means nothing.

I'm thinking MAF sensor or a leaking intake pipe under the airbox?
I have it booked into my nearest indy at Startech Poole on Thursday where I was reminded the diagnostic fee is £120+vat before the serious bill starts
Had it been summertime I might have checked the intake pipe myself but not at this time of year on a driveway. I'm past all of that.

Any thoughts on other possible faults or am I on the right track?
If its the MAF, any ideas on cost?

 

[markjay]

Sorry to hear about your troubles.

A split vacuum hose under the air cleaner box should only cause rough idle, but not cause any noticeable issues when the engine is revved up.

Another common issue, blocked crankcase ventilation breather, should bring up the EML.

Did you check for leaking camshaft position sensors?

Also, it's unlikely to be the timing gear, because the car would sound like a bag of nails.

Kompressor issues? Possibly, but not very common.

Invest in an iCarsoft?

 

[AMGeed]

Sorry to hear about your troubles.

A split vacuum hose under the air cleaner box should only cause rough idle, but not cause any noticeable issues when the engine is revved up.

Another common issue, blocked crankcase ventilation breather, should bring up the EML.

Did you check for leaking camshaft position sensors?

Also, it's unlikely to be the timing gear, because the car would sound like a bag of nails.

Kompressor issues? Possibly, but not very common.

Invest in an iCarsoft?

I checked the cam sensors for oil when I added the wire blockers back in the summer. Little evidence of oil ingress into the plugs.
Once the engine got over 4k revs, it seemed OK which is making me lean towards a split/leaking intake hose.?

A iCarsoft is a good call, but too late for Thursdays appointment at the indy.
I let them down once by not turning up for a service as I caught Covid19 and didn't give any cancellation notice.
I can't do it to them again.

 

[MikeInWimbledon]

That’s not my understanding of “Limp mode” although it’s more than two decades since I experienced it. My memory is that Limp mode is capped revs (below 2,500?) and a restriction to lower gears.

A wiser Engineer will be along in a moment.

(Personally, I would have Amazonned an icarsoft for next day delivery so that you “might” be able to go into the garage saying I’ve got “this” problem and avoid the diagnostic fee. But TBH that’s because I like to know what’s going on, even though I seldom have the skills to do the fix)

Obviously I probably wouldn’t have sent the icarsoft back the following day for refund. I only do that with Jumper packs when someone else has had a battery problem in an obscure place without jump leads to hand.

 

[W1ghty]

So after just over two years of ownership, I have the first problem with the engine. (2009 S204 180k with M271 engine)
Parked up last Fri evening after a non fault drive. Started today and pulling out into traffic I noticed a distinct lack of acceleration,
Coming to a halt in traffic, the revs were fluctuating between 500 and 1k rpm and taking the foot off the brake it was jerking as it crept forward.
Deciding all was not well I turned to return home and on pressing the throttle, the revs rose but there was no power at all and the engine noise increased considerably.
On the 3 mile trip, fuel economy dropped to 15mpg. I'm guessing my first experience of limp mode?
No CEL , no black smoke I could see and no fault codes on my cheap code reader though that means nothing.

I'm thinking MAF sensor or a leaking intake pipe under the airbox?
I have it booked into my nearest indy at Startech Poole on Thursday where I was reminded the diagnostic fee is £120+vat before the serious bill starts
Had it been summertime I might have checked the intake pipe myself but not at this time of year on a driveway. I'm past all of that.

Any thoughts on other possible faults or am I on the right track?
If its the MAF, any ideas on cost?

I was going to suggest the leaking rubber pipe under the air box .

 

[W1ghty]

This was my hose job under the air box

CLK , changed vacuum breather hose A271 018 1282

This had been on my list for a while as a known M271 engine issue . The hose splits and puts the car into limp mode . I had been waiting for some decent weather to attempt the job . The hose I bought some months ago . It’s a fiddly Job and you need to make sure you have the correct tools to...

forums.mercedesclub.org.uk

Second hand MB maf on eBay for £20-30 ??

 

[Will]

You could unplug the MAF and see how it affects things?

Where do you get it serviced Roger, MB offer Mobilo and I reckon they’d assist FOC if needed

 

[AMGeed]

You could unplug the MAF and see how it affects things?

Where do you get it serviced Roger, MB offer Mobilo and I reckon they’d assist FOC if needed

I have been servicing the car myself Will.
Oil/filter/plugs etc. Anything more involved and it goes to an indy.
I haven't used the main dealer for servicing on this car at all, just the previous E class.

I'll try the MAF unplugged tomorrow and see if there is any change in performance.

 

[AMGeed]

Found the problem without a diagnosis fee.
Was going to put some fuel in before taking the car to the indy tomorrow and decided to check with the MAF unplugged and look for any obvious hose leaks. The induction roar was a clue.
I didn't spot it initially but looking under the intake hose I could see the hose that should have been connected to the supercharger had come off.
Took a while to ease it back on and tighten up and I'm still visiting the indy tomorrow for them to check my work and ensure its not going to come adrift again.
Fuel economy and driveability back to normal now. Glad it was a cheap fix.
Still puzzled as to how it came to detach itself though. No WOT driving beforehand it almost looks like someone has pulled it off deliberately.
One of lifes mysteries I guess.

 

[Wearsthefoxhat]

Good find, always worth a quick look just incase….

 

[AMGeed]

Had the pipe checked and fitted properly with a new clip this morning. Well worth the £36 for peace of mind it shouldn't blow off again.
I have to correct my description of that particular hose. It is connected to the throttle valve, not the supercharger. That hose is the horizontal one to the left and below the one displaced.

 

[W1ghty]

Had the pipe checked and fitted properly with a new clip this morning. Well worth the £36 for peace of mind it shouldn't blow off again.
I have to correct my description of that particular hose. It is connected to the throttle valve, not the supercharger. That hose is the horizontal one to the left and below the one displaced.

I better check my M271 next time I’ve got the bonnet up !

 

[AMGeed]

I better check my M271 next time I’ve got the bonnet up !

Always worth a quick check over W1ghty. Still no explanation for it becoming detached in the first place.
Advised by the indy to keep an eye on it and replace if it comes off again.