940 maf

[wakeling]

hey all ,
i have a 940 b200ft engined wentworth and im after a maf as mine is fubar'd msg me if you have a working one and let me know a price or on here, ta!

[rippedoffagain]

Originally Posted by wakeling

hey all ,
i have a 940 b200ft engined wentworth and im after a maf as mine is fubar'd msg me if you have a working one and let me know a price or on here, ta!

I've got one spare, but before you right off the MAF have you made sure that's not a red herring?

I thought mine was dud, but it turned out that other things had led the ECU to think it was playing up when it wasn't. In my case I think it was a combination of things. Bad ignition (the dizzy was fubar, as were the HT leads), and bad breath (the whole induction tract was excessively dirty).

Before writing off your MAF, consider the steps the ECU takes to decide whether the signal is believable or not.

1. Air passes through the MAF, telling the ECU how much fuel to inject to get the right mix.
2. The ECU tells the injectors to open for a particular length of time to squirt the right amount of fuel in.
3. Your engine sucks in the air/fuel mix.
4. The ECU tells your ignition to set it alight.
5. The result exhaust gases are checked by the lambda sensor to see how much oxygen is in there.

Unless the MAF signal is lost completely, the ECU has to guess based on other signals whether or not to believe the signal from the MAF. If ignition problems result in a bad burn that the lambda sensor reports, then it can be assumed (possibly incorrectly) that the MAF is bad.

Another thing to look out for is the flappy valve thing in your air box. It is based on a little thermostat to direct air from a hot or cold channel based on air temp. The thermostat fails and the flappy valve then sticks in the 'hot' position, sucking air from near the exhaust manifold even if the engine (and surrounding air) is hot. After a while it can fry the MAF, but before it gets there it can cause dodgy MAF readings.