Jerky acceleration/Boost codes

[wizard220]

Hi all,

Hoping you can help as google hasn't yielded much.

I own a 2013 C220 CDI BlueEff. While driving the other day (after filling up), car began to suddenly jerk upon acceleration. Pulled over switched off and switched on again, same problem. Eventually by the time i'd got to where i was going the EML was on.

I checked while car not in gear, idle is ok between 770 and 800, but when accelerator down it can jump up and down constantly. In limp mode, i noticed that car was extremely underpowered (compared to previous limp modes) i.e. 5-10 mph uphill.

Scanned car with icarsoft and its giving

P0236 - Boost Pressure Sensor Malfunction (circuit 'A' on OBDC)
P2279 - Intake air system Leak

I've had the P2279 before, so set about checking intercooler hoses, no leak. Found residue beneath pipe going from air box to turbo (when checked, pipe was fine, no cracks, think this was from a previous episode where the jubilee clip needed tightening, but open to checking more). Checked air filter and nothing amiss. Cleaned boost sensor and it seemed to help (a little).

Cleared code and tried again and this time got code:

P0299 - The boost pressure of turbo 1 deviates from the specified value at low engine speed
P0236 - Boost Pressure Sensor Malfunction (circuit 'A' on OBDC)

Did a live read of data

B28/5 Pressure sensor downstream of air filter - 1.01 bar
B5/1 Boost Pressure Sensor - Between 0.57 and 0.62 bar
B60 Exhaust Back Pressure Sensor - 1.15 bar
B28/8 DPF diff pressure sensor - 0.02 bar
Y77/1 Boost Pressure Positioner - 47.11%
Degree of Contamination of Air Filter - 0%

I'm on the verge of pulling the trigger on a new boost pressure sensor, but thought i'd ask the question first. The two codes don't show up together on many google searches for the OM651 engine.

Please help! Tearing my hair out this close to xmas!

 

[wizard220]

Anyone any ideas?

 

[BlackC55]

Yes.

I expect you have a split boost hose. Have a look at the hoses that go to the intercooler. We do them on a regular basis.

 

[wizard220]

Yes.

I expect you have a split boost hose. Have a look at the hoses that go to the intercooler. We do them on a regular basis.

Thanks! I have checked and have not found a leak. After spending some more time I’ve noticed the ‘jerk’ happens on gradual acceleration (as opposed to flooring it) and always around 1.5k revs.

I have scanned again and a few metrics are DPF fill level 103% (does this mean 3% or 103%?), could that cause the jerk?

Video of the revving, notice around 1.5k rpm -

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[wizard220]

Hi all, just to close this one off, found the problem.

Although the codes thrown were related to boost, the actual problem was a clogged EGR valve.

I had planned to take this out to clean, however I hadn’t realised my OM651 appears to have the EGR valve underneath the cooler on the right side of the engine (looking from front of engine bay) and there was no way to get to it save taking the whole EGR system off.

So a £10 canister of Wynn’s down the air intake, and a clear of the codes. Then a long blast on the motorway to clear some of that soot.

So if anyone is experiencing low boost pressure and it’s not split intercooler pipes or a sensor, check your EGR.