Question About Maf Readings

[Mark & Cath]

I have noticed recently my fuel consumption is increasing (1.9TDi AUY engine) and in VAG.COM the MAF specific is 250 but the MAF actual is over 500. I assumed a failing MAF so I swapped it over with a mates but my MAF on his car works fine and his on mine returns the same figures.

 

I am guessing maybe a leak in the intercooler or pipes would cause more air to be sucked in to compensate but that is just a guess lol.

 

Any ideas peeps.........

[MrT]

Not sure on your model but there is an air temperature sensor either integral or nearby and if this has failed, it could mess up the readings.

[Mark & Cath]

Thanks Mr T

 

The air temp sensor is part of the MAP sensor, both temp and pressure reading about the same as the other vehicle. I will try swapping the sensor later anyway and let you know.

 

Thanks for the reply.

[Mark & Cath]

I swapped the TMAP sensor with my friends and no difference. I will have to have a read up and hopefully someone here can chip in.

 

Thanks for the thought Mr T it was appreciated.

[seatkid]

Fuel consumption is not related to airflow which is what the MAF measures. The MAF establishes the maximum fuel quantity that could be injected before emission are exceeded (smoke) i.e. a max power ceiling. When a MAF starts to fail, the ECU thinks the air flow is decreasing so lowers the maximum fuel limit, hence the loss in power.

 

Increasing fuel consumption could be injector problems (dirty!), injection timing, or an EGR problem (clogged) - these last two are usually accompanied with poor power and excessive smoke.

 

Check for simple things like binding brakes (check the rears....) or low tyre pressures.