Hello, my fuel consumption is dropping at the moment (12.1mpg) is it possible to test the maf to prove it good or bad one way or the other. If it does need replacing do I stick with genuine parts?
What diagnostics do you have? You can check the airflow through the MAF and compare it with the spec in RAVE. One of my cars has a genuine while the other an aftermarket and I get the same results from both. GEMS isn't as picky as Thor. Other thing that can cause high fuel consumption is a duff lambda sensor.
Thankyou, I will have a look at Rave this week. Have not got much in the way of diagnostics apart from my nanocom and a multimeter. I do have some spare lambda sensors and a spare aftermarket Maf.
Nano is all you need. You can look at the airflow from the MAF under GEMS - Inputs - Air and Idle - Current airflow. It should be around 20 at idle, rising to around 60 at 2,500 rpm.
You can also look at the lambda sensors under GEMS - Inputs - Fuelling - Pre-cat O2 sensor which will show a voltage varying between 0 and 5V. 0v being rich and 5V being lean but a failed sensor will stick at 5V so the ECU will see that as lean and richen the mixture resulting in increased fuel consumption. You've got two identical pages for bank 1 and bank 2, bank 1 being the LH bank (as seen from the drivers seat) and bank 2 the RH bank.
Thankyou that’s very helpful. She will get a bit of a run today so I’ll connect up the Nano and check. Helps to know what to look for. 😄
Road test today O2 sensors are working ok. Current air flow @2500rpm over 400
That isn't good. If it thinks that amount of air is going in, it'll be richening the mixture to keep the air/fuel ratio correct. I suspect the lambda sensors were showing nearer 0V more often than 5V too. You'll need to reset the adaptive values when you change the MAF as it will have adjusted the fuel trims way off to compensate.
Will do thanks, they are a bit pricey at Rimmers.
They certainly are, but that is for genuine LR. GEMS isn't as picky as the later Thor, so decent make aftermarket are fine. I've got a genuine one on my car and an aftermarket on the Ascot and both give near identical readings. There's these https://www.lrdirect.com/err5595-air-flow-meter, take your pick. Although Island don't seem that impressed with the Bearmach ones https://www.island-4x4.co.uk/mass-airflow-sensor-gems-9498-bearmach-err5595-sold-with-warranty-p-5262.html
Part ordered from LR direct. Looking forward to fitting it and making her happy again.