S211 220CDi surging under power

[RWEngineering]

Hi Guys,
I have a 2008 211, 220 CDi.
The problem is that at anything over 50>60% throttle it surges. It accelerates for 1 or 2 seconds, then it goes flat for a second, and then repeats, over and over.
It feels like fuel starvation, maybe a fuel rail pressure issue?
Can I monitor the pressure live with a diagnostic tool?
Any ideas?

 

[91dm]

Could it be the turbo actuator?

A good OBD scanner can give you live data. Any lights on the dash?

 

[m80]

Torque on an Android device can monitor fuel rail pressure. That's free, but a few quid for the pro version
An OBD EML327 transmitter will cost £5ish for a cheapo, they're less reliable. £14ish gets a better one.
It'll do basic fault codes also.

I would consider the turbo actuator as well.

Great for the price, if somewhat basic.
A good starting point.

 

[mersum1es]

fuel starvation (=low rail pressure) usually cuts down engine totally. My vote is exhaust back pressure sensor (not betting same horse as above, even turbo actuator is a good call too)

 

[RWEngineering]

Interesting, I'll plug the scanner in and see what the pressure does,
How do you check the function of the Exhaust back pressure sensor or the Turbo actuator?

 

[m80]

Turbo actuator should travel full range when the ignition is cycled.
So some one needs watch it move.

 

[amazighman]

It may not apply to your case ,but in my W203 C220 CDI I had exactly the same issue , replaced few components like turbo actuator ,fuel filter etc

Accidentally found out that the transmission fluid level was low. Did fluid change and set fluid level correctly and hey presto ,no more issues

 

[RWEngineering]

That's another good thought, cheers