MPG and MFA

[jslootweg 0]

Right I have been looking around the forum for some time now and haven't found the answer i have been looking for. When I drive my 2.0l 16v around the MFA MPG reading gradually creeps to around 60-70MPG then stops. I don't know why? Also my car seems to be doing about 26mpg round town and 30 on motorway, i think this is a bit low. Are the 2 connected at all, or are they completely seperate problems?

 

Thanks

[Phil K 0]

26 and 30 seems about right to me tbh... haven't a clue whats causing the other problems though :?

[jslootweg 0]

I have read of people getting between 35-40ish on long drives, but averaging in the 30s most of the time. The best i have ever done is 30mpg.

[mattosmond 0]

i guess some people are a bit too trusting of their mfa, when it says 40mpg or such like! i think you need to take it with a pinch of salt. ifi t says 35mpg then your probably getting more like 31 - 33 mpg.

i Wouldn't have a clue what your problem is with the mfa! unless it is taking the actual mpg in stead of average,,,,, where sometimes if your cruising just touching the gas then it will say ridiculous figures!!! it did on my mk4 golf 1.6...

[jslootweg 0]

Yeah the MFA is weird, because at the begining of my drive its a very low number, and the number just keeps creeping upwards until it reaches a number around 60. Does anyone know whether this a problem with vacuum pipes? or is it electrical. I have had a look around the 2 vacuum pipes that come from the throttle body, and there is one that goes behind the heat shield behind the exhaust manifold, but that looks ok to. I wouldn't mind if the MFA was a bit optimistic but 60-70mpg would be daydreaming!

[jslootweg 0]

I think the MFA is showing about double of the actual MPG anybody had this problem before?

[filski 0]

hi,

i get on ave about 30 mpg and even up to 35 mpg on long motoway travels, which gives me about 330 miles to a tank. if it goes up to 60 mpg then i think it is not showing true, as that would be very high, great but very high.

[dr_mat 0]

The 2.0 16v MFA is driven off the ECU, like on the VR, I think. This means that the ECU is calculating the number you see on the screen based on it's record of how much fuel it has put in the engine, and how far you've travelled.

Does the MFA trip mileometer work ok? Sounds like your 30-35 mpg is about right for a motorway journey, so it seems that the problem lies in the ECU ...

[jslootweg 0]

Yeah the trip meter seems to be working fine. Infact the whole MFA works fine, its just the MPG that seems odd. Is there anything somebody could have done to the car to confuse the ECU?

[corradophil 3]

For reference I reset my mfa and filled my car to the brim, I then ran it till nearly empty, and logged the miles covered and fuel used. I then calculated the mpg. My mfa on the long term setting read 1mpg lower than I calculated. IIRC the mfa said 29.8 and I made it 31.

[matthewb1985 0]

jslootweg mine does exactly the same slowly rises to about 68 mpg and doesnt go down. not solved it yet would be interested to know how

[dr_mat 0]

Does the magic MFA trick work on the 2.0 16v? The one where you get instantaneous MPG instead of the rolling average?

I think it's something like

- ignition on

- press and HOLD the MFA stalk control button

- ignition off (KEEP holding the button)

- ignition back on (STILL holding the button)

 

At least I think this is the sequence. You should now see instantaneous MPG. This works on the VR6, anyway ...

[davidwort 0]

I think the MFA is showing about double of the actual MPG anybody had this problem before?

 

I think the 2.0 still uses the manifold pressure (vacuum lines) for calculating mpg, the ECU certainly has a vacuum connection although that may be for load. If there is a vac tube going to the back of the instrument cluster then it will.

I can't see the ECU knows how much fuel the 2.0 16v has used as the injectors are still basically mechanical K-jet and so constantly flows throughout the engine cycle.

My guess would be a vacuum leak, which may contrubute to the poor MPG.

As an extreme my 2.0 16v, but with the 1.8 fuel system, did 332 miles on 39 litres of fuel last week on steady slowish motorway cruise, that's nearly 39 to the gallon. More generally I get from 30-35 average with mostly dual carriageway driving to and from work.

[eatthis 0]

Does the magic MFA trick work on the 2.0 16v? The one where you get instantaneous MPG instead of the rolling average?

I think it's something like

- ignition on

- press and HOLD the MFA stalk control button

- ignition off (KEEP holding the button)

- ignition back on (STILL holding the button)

 

At least I think this is the sequence. You should now see instantaneous MPG. This works on the VR6, anyway ...

 

im gonna try this when i get my golf back how do i cancel it?

[jslootweg 0]

Yeah it sure does work, tried as i left work, but the number jumps all over the place dependant on the current engine load.

[eatthis 0]

Yeah it sure does work, tried as i left work, but the number jumps all over the place dependant on the current engine load.

 

thats because its instant mpg im gonna see how low i can get mine lol

[dr_mat 0]

It's cheating if you go for a low number while you're on cold-start enrichment, by the way..

 

I saw 9mpg on the VR once, when it was warmed up. ISTR that was at full throttle in 3rd @ around 70 mph ...

[eatthis 0]

im not gonna do its cold as i NEVER use wot or go over 3k rpm till the oils over 70 its easy to get 99.9 mpg by doing over 2k rpm then coasting in gear as u dont use any fuel watsoever