W906 313 CDI 2012 High Fuel Consumption

[no2spam]

My Mercedes Sprinter (W906 313CDI 906.135) has had very poor fuel economy lately. When I bought it it was getting around 25 MPG on the motorway, after the dealer updated the ECU software to fix the emissions the fuel economy went up a bit and the van was getting around 22-24 MPG. But lately it has gone up to 17-19 MPG.

Sometimes I have to reset the error code P2A0064 Oxygen Sensor 1 (Bank 1) has a fault. There is an implausible signal (STORED).

There are no leaks under the van (engine running or off), the van does not smoke, does not consume oil, there are no visible diesel leaks around the injectors. The fuel filter was changed 2 months ago. According to Xentry, the fuel rail pressure is normal.
Can a faulty lambda probe/oxygen sensor affect the mileage so much? Maybe the dealer flashed the wrong version of the firmware? Need advice on what else I should check.

I have ordered a replacement Bosch lambda probe and am awaiting delivery.

More information about my Sprinter van:

• 2012 MB SPRINTER W906 313 CDI 906.135
• Engine OM651.955 DE22
• Delphi CRD2.35 ECU
• Details from Xentry about CDID2 Common Rail Diesel Injection module
• MB NUMBER 6519019400, HW VERSION 10.02.00, SW VERSION 08.15.01, DIAGNOSIS VERSION 021218
• FW NUMBER:
• 6519020100
• 6519027403
• 6519036574

 

[Aleks991]

The O2 sensor plays an important role in the fuel mixture. If the O2 sensor is not working properly, of course you will have higher fuel consumption because the ECU detects the gas flow and based on that the system adjusts the injector and the amount of diesel. One possible reason is that leaky injectors do not actually spray the vapors properly, they only spray diesel, and then you will have higher fuel consumption and the car will run a little weaker and you will smell diesel in the cabin from time to time.

 

[deathpilot]

Check the O2 sensor for clogging. When the EGR is not working properly or you have leaks in the air system, the EGR velocity is too high and this happens. Then the small holes in front of the O2 sensor get clogged. Check for leaks under the intake manifold. Sometimes the screws under it are broken.

 

[lauajoe]

The O2 sensor OM651.955 DE22 is easily clogged and damaged. It is recommended to remove the O2 sensor and clean it every time you change the oil.

 

[Mersovod]

The dealer cannot choose the firmware version, only install the most current one at the moment, if there is one. Updating is not always useful. Replace the lambda probe and take a test drive. Before replacing, check the wiring to it. You can reflash the old version using Monaco, but the dealer will not do this. And you need to know the number of the firmware that was installed previously.

 

[no2spam]

I replaced the oxygen sensor but the fuel economy did not improve. No fault codes at all.
Upon further investigation I found that injector #4 was in black death (thanks Alex). I took the injector out, cleaned injector and the port hole from gunk and put it all back with a new seal and bolt. At least the smoke in the cabin is gone now. Fuel economy has improved slightly from 18 MPG to about 20 MPG.

The next step is to have my old set of injectors rebuilt and calibrated at an authorized Delphi garage center and installed. I bought the current set of injectors from a mechanic as refurbished, but I'm starting to doubt how well they were refurbished.

 

[no2spam]

Also the van had a problem with loss of power since purchase. After replacing the injectors (refurbished) and the intake manifold the power increased significantly. But the engine loses power from time to time, mainly when driving uphill.

Today when I was trying to overtake a truck on a hill I felt like the van was in limp mode (no faults, no EML lights) and I could barely get past 50mph no matter if it was in 5th or 4th gear.

I couldn't find a way to run a test in Xentry that would show the performance of the fuel injectors, so I used the Torque limitation test in the Actual Values section.


The only reading that stands out is the oil temperature of 110.5°C. Almost immediately after the oil temperature reaches 110°C, the engine goes into limp mode. I'm thinking about replacing the thermostat because as soon as the engine idles, the coolant temperature drops below 75°C very quickly. The other day I failed to get the engine up to 80°C while the van was parked to reset the Xentry's injection volume.
I also think the oil heat exchanger is nearing the end of its life.

I changed the oil and filter 2 months ago (about 6000 miles ago). Castrol Edge 5W30 LL oil and genuine MB filter. I check the oil level every few days with the dipstick and it stays the same. When I changed the intake manifold, I did not find any serious oil leaks.

Could you please help me understand the Xentry Torque limitation test readings (09/2023 data)?
To connect to the van I used VXDIAG VCX SE.
Any ideas are welcome.

P.S. I don't understand why line 11010 showed that the engine is not running, although I did a real test drive.

 

[PeteM123]

Hmm. I'm also wondering if it's possible to refurbish injectors at all and how well it can be done.
Flushing and cleaning can also be performed if the cause of the malfunction is poor quality fuel.
But if the very fine spray nozzles are damaged, clogged or excessively worn, I hardly see any chance of repairing them.
Changes in fuel injection timing (individual injectors become blocked), an oversized injector (increasing in diameter due to wear) and/or a soft spring (causing fuel leakage) will result in increased fuel consumption.

In my opinion, using refurbished injectors will require a guarantee from the supplier/seller of their serviceability. Personally, I would not risk changing them twice (first for refurbished ones, and then again for new ones, having found that the problem has not disappeared).
But I'm interested to know if the old but calibrated injectors work.