I'm not a Vivaro or Primastar man but if it helps this is what TIS says for the F9Q/760/762 engines

Tester Display Mass Air Flow Sensor

• Engine running at idle speed, operating temperature
• All consumers turned off
• Accelerator pedal not actuated

30 ... 45 kg/h

• Accelerator pedal briefly actuated to full load stop

greater than 350 kg/h

 

Top Man
Thinking I might be a bit short of that figure.
Could my blanking of EGR make a difference? Guess not because it's after the MAF?

Thank-You

 

Blanked EGR will have the effect of increasing the MAF readings at a given rpm, as now the EGR is not recirculating exhaust gas into the cylinders, they become charged with more air, which is obviously drawn through the airflow meter.

Systems like Bosch EDC16 (a la 1.9cdti's) use this MAF reading to figure out if an EGR is blocked/stuck etc as it knows how much airflow it should be seeing at a given RPM/load/throttle, and hence why no EGR feedback on the actual valves on those systems.

Suspect your van isn't sensitive enough to pick up that the EGR has been blanked. Your idle figures are slightly up so this makes sense. I bet fully revved wouldn't be far off either. Have seen airflow meters fail on these but normally open circuit and fault codes.

At least she's running a treat now

Nick.

 

So now you've opened the can of worms!
The dilemma of the readings.
Is the MAF reading correctly and you have a restriction/leak in the Turbo/Intercooler pipe work?
Is the Turbo operating correctly?
Is the MAF reading incorrectly and everything else is OK, except now the injectors wont be getting the correct pulses to the corresponding RPM?
If you had a MAF that was known to be reading correctly (where you'd get one from is a mission) you could fit it and check if the readings are correct or not?
If you bought a new (Siemens) one and checked again and the reading where better it would go some way to proving the original was under reading, as long as you accept that the new one could be over reading and just as far out?
Buy, borrow or hire an air flow meter, if you can find one that will do the job, as most cheap ones are made for wind speed (mph,kph etc) not Kg/h.
you just couldn't be happy with it running OK, you had to go and tinker with it, now look what you've started

 

So now you've opened the can of worms!
The dilemma of the readings.
Is the MAF reading correctly and you have a restriction/leak in the Turbo/Intercooler pipe work?
Is the Turbo operating correctly?
Is the MAF reading incorrectly and everything else is OK, except now the injectors wont be getting the correct pulses to the corresponding RPM?
If you had a MAF that was known to be reading correctly (where you'd get one from is a mission) you could fit it and check if the readings are correct or not?
If you bought a new (Siemens) one and checked again and the reading where better it would go some way to proving the original was under reading, as long as you accept that the new one could be over reading and just as far out?
Buy, borrow or hire an air flow meter, if you can find one that will do the job, as most cheap ones are made for wind speed (mph,kph etc) not Kg/h.
you just couldn't be happy with it running OK, you had to go and tinker with it, now look what you've started

Good point!!
I like the idea of a flow meter! Could map actual air Flow against the sensor! Got me thinking now
I will have a proper look at hoses etc make sure I'm not leaking anywhere!

 

That could be it then, that the ECU can calculate the difference between actual airflow and what it expects to see, because it's assuming th EGR is still functioning normally.

Nick.

 

I'm not a Vivaro or Primastar man but if it helps this is what TIS says for the F9Q/760/762 engines

Tester Display Mass Air Flow Sensor

• Engine running at idle speed, operating temperature
• All consumers turned off
• Accelerator pedal not actuated

30 ... 45 kg/h

• Accelerator pedal briefly actuated to full load stop

greater than 350 kg/h

Quick update.
Checked my van again at full throttle and got 275 kg/h.

Replaced the MAF with a new genuine one and now I'm getting:
Idle. 55 kg/h (still high but as Nick says EGR blanked so more air past sensor into engine)
4000 rpm 350kg/h. (Full throttle so no EGR, hence plausible reading.)

I reckon at flat out that's nearly 30% increase in the air the engine thinks it's consuming. Got to help!
Thanks everyone for there input.

 

That's a huge difference, nice one. Great to have real world results to back up the theory, happy days.!

Nick.