No turbo when warm

[philreed52]

Hi all
Have been having problems with my clk 270cdi with 170k on clock .Have posted previously and had 2 indys put it on diagnostics without finding a fault except once when I got a rail pressure code that once cleared and had fuel filter change has not re occurred.
Since then my wife has used it for short journeys to work with EML coming on and off after 4 starts with turbo sometimes working or not.
I have started using it again for a 20mile run to work and observed this fault rears its ugly head as the engine gets warm typically about 4- 5 miles loss of turbo the rest of way to work ( 15miles) .if I stop turn engine off and restart turbo back but only for about a mile .Same on way home .
Is there some fuel sensor that causes that change when warm .The car runs as it should with or without turbo except for obvious lack of grunt but climbs a fairly steep hill home easily without turbo .
When turbo working it is nice and responsive .
It will be booked back in after xmas but if I can have some pointer might try fixing it myself .Pretty competent diy as used to build kit cars and years ago (quite a few) served apprenticeship for mechanics .

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[Larkone]

Turbo actuator? Can be cleaned and re-greased or sent for refurb. Easier than replacing because they are coded to the turbo

 

[mioba]

Actuator my first thought too. Replaced mine on the w251 this year.
You can replace once old one is off and get the same numbered one.

 

[philreed52]

Actuator my first thought too. Replaced mine on the w251 this year.
You can replace once old one is off and get the same numbered one.

How difficult a job to do ? Can the car be driven whilst it's off being returned for refurbishment? Does it not show a fault code though as my indy was quite convinced that was working ok, but these people aren't always right . The spanner in works that on hard acceleration from standing start ( when turbo works) it pulls away then stalls but restarts immediately. runs as normal?? It is really frustrating that it can't be pinpointed .What happened to the good old mechanical diesel so much easier to fix !!! But love the new power and goodies .You can't win

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[Botus]

what diagnostic kit are they using?

my fathers didn't throw codes just drove flat, if you ragged it there was boost at higher revs but not much, a 50 quid sensor that measures pressure near the EGR failed, swapped it out and it was back to normal

check here https://forums.mercedesclub.org.uk/...-motor-delete-cdi2.97061/page-14#post-1868316

 

[Botus]

most independent garages do not have great diagnostics and seldom update the software. generic kit won't always find all info about issues

I was at a big independent jag garage in the summer after just getting a bit of my snap on kit updated by the van man....

owner in a ratty F type came in asking about a fault. the tech went out with a 10k bit of diagnostic gear and battled for 25 mins, came back and got their other kit they knew needed and update 15 mins later sent him on his way

I said did you fix it, "no, Our kit couldn't work on a car that new so I said go see a main dealer." so what was wrong with it "it was what you were just talking about.... "

the bonnet pedestrian safety air bag had gone pop. A 1200 quid fix, I'd read about an owner who'd had it happen twice, after coming out of his house and going too quickly over speed bumps. After a lot of legal hassle Jag paid. The second time 18 months later an amendment to the owners manual existed and so Jag and ombudsmen agreed its the owners problem now… basically the manual amendment said "we can't be bothered to sort the problem... drive slowly over bumps or expect it to pop"

 

[ajlsl600]

Jag must be havin coffee with benz . I will be gettin rid of ml before"I" have to pay for that version of makers screw the owners.

 

[philreed52]

what diagnostic kit are they using?

my fathers didn't throw codes just drove flat, if you ragged it there was boost at higher revs but not much, a 50 quid sensor that measures pressure near the EGR failed, swapped it out and it was back to normal

check here https://forums.mercedesclub.org.uk/...-motor-delete-cdi2.97061/page-14#post-1868316

One garage used snap on the other had a star system .it was quite an impressive set up with a laptop hitched up to a whole lot of gear on a small trolley. He was able to rev engine etc from laptop .it looked quite good and he is a Merc specialist and used to work for main dealership..
Just a silly story about tech v common sense. My mate had big yank car that went in and out of garages with same fault they could not diagnose it finally broke down completely and RAC shipped it to me as love yank cars and he asked if I could look at it .After a hour on it manually checking fuel,spark and compression all were ok .Noticed coil was wet and oily .Changed coil fixed .Coil is oil cooled and had a leak so overheated and failed until it cooled down again .old fashioned checks . Not so simple nowadays though.


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[Botus]

Jag must be havin coffee with benz . I will be gettin rid of ml before"I" have to pay for that version of makers screw the owners.

it really is criminal. so they designed a safety feature that gets troubled in daily use with forces coming at the car in ways that have got nothing to do with running people over... that's a fault related to one or all of these points !

the sensor is wrong for the application
the fitment is in the wrong place
and or the software is part baked

= recall to fix it

 

[Botus]

once you have a clue, lots of useful info tends to be in the "live values". Most faults are common and one bit is playing up. Know what to look for, check the values on diagnostics and find x is reading garbage, so either:

a wiring fault (rare),
a sensor fault (common)
an actuator playing up (maybe - usually age related - not mileage)
the ECU gave up (becoming problematic on modern cars)
the Software has a few extras and a poke with a sharp stick might help (or make it worse if the manufacturer is a naughty boy)

 

[John Laidlaw]

Any unusual smoke?

 

[ajlsl600]

A temp sensor. Sayin motor too warm and stopping turbo Makin more boost, heat??, keeping waste gate open? Pre all emissions electronic shite the brain? In seat looked temp Guage and operated the car accordingly.
In yr case read codes react from there. One has to understand that a decent code reader, diagnostics system, or deep pockets is now a pre requesite for purchase of these cars. Much advise on which is avail on here.

 

[philreed52]

Any unusual smoke?

No unusual smoke it actually runs beautifully with or without turbo the latter obviously lacks the grunt .its the scary bit when you try to overtake or boot it from a junction and it goes into cardiac arrest ( I nearly did too the first time it happened when over taking fast) pulled over and started as if nothing happened .Garage had it next day showed rail pressure fault .Changed fuel filter that fault never returned ( fuel filter was only 6 months old) suspected dirty fuel and no fault for a few weeks . It is very frustrating.

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