mpg computer.

[jonnyr]

i have a 2lt gti golf mark 4, and the trip computer for the mpg is going mental, one minuite is says im getting 40 mpg then it says 150 mpg then 19 mpg and so on, i need help

[euroslap]

i have a 2lt gti golf mark 4, and the trip computer for the mpg is going mental, one minuite is says im getting 40 mpg then it says 150 mpg then 19 mpg and so on, i need help

They constantly change in this mode due to throttle position/ incline etc. if you switch the MFA into the other mode it'll give the average (can't remember which switch position is mode 1/2 on the stalk).

[jonnyr]

thanks mate put the switch on mode and it is not going mental anymore

[jonnyr]

sorry ment to say mode 1,now im going mental

[chillerz]

Hi,

How do you switch the MFA Mode? Also my car battery died and now there are some strange symbols on the screen of my golf. There is a 1 in the top right hand corner of the screen and before the mileage there is a Ø before the mileage. Usually I would just ignore it but it is affecting the mileage on my car. Any ideas on what this is?

[batteryman]

Can't get the greek symbol on my keyboard (don't have time to search it out) but it means average figure rather than instant. I think the 1 refers to the mode setting, 1 for single trip and 2 for cumulative over 2500 miles (may be the other way round). The MFA mode is switched by pressing the square button on the underside of the stalk; holding it in resets the data to zero.

[chillerz]

I used to get 120 miles out of £20 worth of petrol and since the battery has died it barely gets over 80 miles from the same £20 and fuel prices have dropped since then. MPG is only showing about 17-20 on the computer. The mileage on the computer used to shoot up and down all the time but now it barely creeps up no matter if I put my foot down or drive normally. Any ideas guys. Thanks

P.S. Where is the stalk?

[chillerz]

OK,

A little bit of quick research has shown me that there can be problems with the MAF. What is the purpose of the MAF, how can I find out if mine is knackered and where is it located. Is it difficult to replace.

[batteryman]

Coming back to you about mpg computer. The "stalk" is the RH column stalk controlling the windscreen wipers. On the end of the stalk is a rocker switch which steps the display up and down through various readings - time, distance travelled, average speed, mpg, average mpg, outside temperature and maybe something more I've forgotten. On the underside of the stalk there is a small rectangular push button. This switches between MFA 1 and MFA 2 when pressed once and zeros all mileage and mpg figures when held in. MFA 1 and 2 are memories for single journey readings and multiple journey (up to 2500 miles then auto reset) readings. I can't remember which way round they are but if it's set to single journey it reads zero when you switch on the ignition. The single journey readings include stops of up to 2 hours. To check mpg consistently I set mine to read average mpg (your greek letter showing) for single journeys. The mpg changes rapidly to begin then settles to an average. The more miles you do, the more slowly it will change in reponse to heavy acceleration or prolonged period of frugal driving. Keeping an eye on this average mpg figure will give you a consistent mpg figure which should tell you if anything's wrong.

The MAF is the airflow meter; its purpose is to measure the amount of air going into your engine and provide a signal for the engine control unit (ECU), the computer which controls the fuel injectors and ignition. It's on the air filter box, not sure which side on a petrol car but this link should give you an idea:-

http://www.carbasics.co.uk/how_to_ch...mass_meter.htm

Vagcom readout will tell you if it's faulty; they're easy to replace and the best place to buy is a VW dealer buy quoting the part number from your old one or the car's reg no. which they can look up on their database. If you change it yourself, the fixing to the air filter box may be different. On my diesel it had bolts and these screwed into captive nuts moulded into the plastic of the air filter box. When I tried to undo them the bolts just turned without coming out. The plastic had chewed up because it was warm and soft - I should have let the filter box cool right down befroe starting.