2005 c220d down on power (ive tried all the normal stuff)

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seanyb

New Member
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Sep 4, 2019
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8
Location
Tyrone
Car
c220d 2005
as the title says, its down on power but only intermittently. while driving (automatic btw) there is boost but no kickdown boost. if i switch the ignition off/on quickly while driving the kickdown boost comes back and stays for miles at a time

there are no faults in the engine or gearbox of any kind
the turbo was removed and set by a specialist (looked tampered with)
replaced the inlet manifold as the swirlflap motor was broken
replaced fuel filter
removed tank pumps and cleaned, they were excessively dirty
rail pressure/boost pressure ok
removed all boost pipes and intercooler to check. all ok
replaced valve body in autobox, along with oil and filter
the two cats have been completely hollowed out though our turbo man reckons this shouldn't be an issue. im skeptical there
the egr is free, clean and operating
tried another airflow meter, map sensor and boost pressure sensor.

im lost at this point, any and all suggestions welcome. fire is apparently not an option :/
 
What does engine temperature shows (by star, not car own gauge), what is boost temp showing? Both false readings may decrease the power. IIRR this car has still 'old' star shape hp pump and thus no fuel temp sensor, CR3 system that could be one culprit for power down.

Engine revs over 3000rpm when fault is on?
 
What does engine temperature shows (by star, not car own gauge), what is boost temp showing? Both false readings may decrease the power. IIRR this car has still 'old' star shape hp pump and thus no fuel temp sensor, CR3 system that could be one culprit for power down.

Engine revs over 3000rpm when fault is on?
engine coolant temp lowest: -273C highest (present) 77C
fuel temp lowest: -273 highest (present)31C
oil temp lowest -1040C highest (present) 70C

those low temps seemed to flash just as i entered the live data tab.

edit: yes it will rev above 3k but slowly, if i dab the accelerator.
 
All readings when fault is on? Lowest temps shows like there has not been supply voltage when readings recorderd. Car is not at limp so no fault code, deffo sounds like intentional power decrease... And what is boost temp? Can you see injected fuel amount, and boost pressure when flooring the car? Not that I could say what they SHOULD be but someone else might...
 
All readings when fault is on? Lowest temps shows like there has not been supply voltage when readings recorderd. Car is not at limp so no fault code, deffo sounds like intentional power decrease... And what is boost temp? Can you see injected fuel amount, and boost pressure when flooring the car? Not that I could say what they SHOULD be but someone else might...
i can recreate the fault simply by switching the ignition off and back on quickly most of the time.
boost temp when running well topped out at 41C, topped at 28C when not running well.
injected fuel amount when running well topped at 77mc/cycle. when not running well it topped steady at 42mmc/cycle

@91dm the car is perfect at idle, smooth as you'd want. no excessive smoke.
 
hmm.... I have a dim memory that standard max fuel amount is around 70mg, is the engine remapped? What is boost pressure at full blast? 42mg/hub also would indicate that something is decreasing power, without triggering a limp mode... tricky one. OM651 with delpi injectore would do that due to injector inner 'observer' but this is bosch system AFAIK

Edit: I digged a little bit, MB injection is basically pressure controlled, now if boost pressure sensor gives too high values it might decrease injection. Now when all temperatures seems to be low enough.
 
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hmm.... I have a dim memory that standard max fuel amount is around 70mg, is the engine remapped? What is boost pressure at full blast? 42mg/hub also would indicate that something is decreasing power, without triggering a limp mode... tricky one. OM651 with delpi injectore would do that due to injector inner 'observer' but this is bosch system AFAIK

Edit: I digged a little bit, MB injection is basically pressure controlled, now if boost pressure sensor gives too high values it might decrease injection. Now when all temperatures seems to be low enough.

thanks for the reply.

im not sure if its been remapped, is there anything i can look at to determine this? either physically in the car or using diagnostics? the last guy never mentioned remapping. boost pressure at full blast was about 2.5bar.

would this pressure be reset everytime i flick the key off/on? alsoin the mornings, sometimes it boosts from 1st startup ok then others its "limping"
 
2,5 bar? :eek:
Definately mapped or then sensor gives too high readings... standard is around 1.5bar
See what pressure sensor reading is when engine is not running, and compare it for example exhaust pressure reading...

Edit: not sure if pressure sensor is capable such a high readings... what I have read remapped max pressure are under 2 bar. Which brings me to next culprit; turbo vane ring or actuator is jamming. Is this turbo still vacuum controlled (liek I assume) or electrical one (I never have got 100% sure information how W203 hardware was changed during model years)
 
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2,5 bar? :eek:
Definately mapped or then sensor gives too high readings... standard is around 1.5bar
See what pressure sensor reading is when engine is not running, and compare it for example exhaust pressure reading...

Edit: not sure if pressure sensor is capable such a high readings... what I have read remapped max pressure are under 2 bar. Which brings me to next culprit; turbo vane ring or actuator is jamming. Is this turbo still vacuum controlled (liek I assume) or electrical one (I never have got 100% sure information how W203 hardware was changed during model years)

the boost pressure peaked at 2.5 (during gear drop). it was 2.1 when cruise boosting. its an electronic turbo. one of the screws were missing from the ecu on the actuator so i sent the turbine to a specialist and he set it to factory and cleaned it up. as far as im concerned its ok, but thats me maybe placing to much faith in him.
 
If turbo has been fully disassembled and opened, turbo frame and compressor housing relative position will affect how the variable vane initial position is set (controller is on the housing, vanes in the main frame). Wrong position cause problems of course.
 
If turbo has been fully disassembled and opened, turbo frame and compressor housing relative position will affect how the variable vane initial position is set (controller is on the housing, vanes in the main frame). Wrong position cause problems of course.
when driving, the boost pressure is in around 1.8/2.2 bar. the inlet manifold pressure is 1.08 bar steady. there are no sensors on the inlet manifold though. the boost pressure sensor is fed from the throttle valve and the sensor on the boost pipe is boosted air temp. where is getting this "manifold pressure" reading from?
 
That way too high pressure, IF it is real value. What boost sensor shows when engine not running? Sorry I cant remember how W203 OM646 is actually sensored.

I think your options are:
- Pressure sensor gives faulty reading
- Turbo actuator is misaligned and causing extreme boost
- Turbo vane ring is jammed
- Remapping is messing up all controls
 
That way too high pressure, IF it is real value. What boost sensor shows when engine not running? Sorry I cant remember how W203 OM646 is actually sensored.

I think your options are:
- Pressure sensor gives faulty reading
- Turbo actuator is misaligned and causing extreme boost
- Turbo vane ring is jammed
- Remapping is messing up all controls


boost pressure ignition on, engine off = 984hpa (.98 bar)
 

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