W203 C220 CDI OM646 boost issue

[amazighman]

Hi chaps.

I had this problem for quite some time and i haven't been able to identify the problem... No fault codes either.

What happens is that when the engine is warmed after like 15 mile drive , I get this lack of power under acceleration and car feels gutless, the RPM needle seem to hesitate , fluctuate and doesn't want to climb or climb then stop then climb again when I press gas pedal , Unless I floor it then it goes ok

I thought It might be stuck turbo vanes , I put some turbo vane cleaning additive in the tank twice , some improvement but problem still happens especially after long drives .

I plugged in Icarsoft 980 and drove back from work 17 miles keeping an eye particularly on the charge pressure positionner ( hopefully means Turbo Actuator) , it seems to work fine values go up and down as I accelerate and ease off , However when I press the pedal down trying to accelerate and the hesitation happens then the charge pressure positionner value is showing stuck at 95% and car feels gutless again untill I gas more then the value drops.

Could it be turbo actuator thats playing up?

Thanks

 

[BlackC55]

Yes it could be. Your diagnosis equipment may not be puling all the codes either.

 

[HITECH]

If revs go all the way up but no power usually the back pressure sensor, situated behind the dipstick. if u have a limp mode problem where it does not rev above 3000rpm then most likely a boosting problem due to a leaking boost hose (a common problem on this car).

Hi chaps.

I had this problem for quite some time and i haven't been able to identify the problem... No fault codes either.

What happens is that when the engine is warmed after like 15 mile drive , I get this lack of power under acceleration and car feels gutless, the RPM needle seem to hesitate , fluctuate and doesn't want to climb or climb then stop then climb again when I press gas pedal , Unless I floor it then it goes ok

I thought It might be stuck turbo vanes , I put some turbo vane cleaning additive in the tank twice , some improvement but problem still happens especially after long drives .

I plugged in Icarsoft 980 and drove back from work 17 miles keeping an eye particularly on the charge pressure positionner ( hopefully means Turbo Actuator) , it seems to work fine values go up and down as I accelerate and ease off , However when I press the pedal down trying to accelerate and the hesitation happens then the charge pressure positionner value is showing stuck at 95% and car feels gutless again untill I gas more then the value drops.

Could it be turbo actuator thats playing up?

Thanks

 

[amazighman]

I don't think this car has a back pressure sensor... It has no dpf

 

[HITECH]

it wont have a DPFE sensor then but will still have a back pressure sensore i reckon

 

[amazighman]

I ll have a look if it's there behind dipstick....

 

[HITECH]

A lot of mechanics who have not worked on Mercedes cars get confused with back pressure sensors and O2 sensors (absolutely no dis-respect to them) and assume when a back pressure sensor is mentioned that it is the O2 sensor being spoken about which isnt the case. 2 completely seperate things.

I ll have a look if it's there behind dipstick....

 

[amazighman]

I cant see any.... All i found was the charge pressure sensor connected to a hose just before the EGR

 

[HITECH]

Can you send me picture of that egr valve area and roundabout

 

[amazighman]

See picture below

 

[HITECH]

If you look down to the right of the EGR valve behind the fuel filter Its quite deep down there coz its awkward to get such a big socket onto it. It should be there. Look for the electric socket wires coming off it. Will be like a kinda spark plug. with the connector plugged into it.

See picture below

 

[amazighman]

How was your car behaving when that sensor failed?

 

[HITECH]

Exhaust manifold pressure sensor - P0471 | Engine

Hi Working on the car today. I’ve got a loss of power but does not restrict to limp mode. It’s down on power over 60mph. Can still go past 3000rpm just seems like it’s struggling. Got a P0471. Can somebody give me a price on a new sensor please ? The DPFE sensor I’ve ruled out. Defo the exhaust...

forums.mbclub.co.uk

Might not be same fault/solution but sounds very much like it.

How was your car behaving when that sensor failed?

 

[ukhan]

Facing a similar issue here. Were able to find a solution?