No MPG on MFA

Everything else works on the MFA but the MPG just comes up as —-
Any ideas?
Vacuum pipe off maybe??

Yep vacuum pipe I guess?

i get that on the engine temp i think, its the last one anyway.

It might just be the vacuum pipe - check that it hasn't melted where it comes into contact with the engine.

However - my MFA is also kaput when it comes to MPG, despite sorting out the vacuum pipe.

The analogue MPG needle is fine (so it's not the vacuum pipe). The yellow up-shift light works (or rather, would work if there was a switch on the gearbox) so the rev sensor works, and the engine oil temp reads correctly - so that works.

However - the avg speed reading is dodgy.

So i reckon my problem is the speed sensor - which is apparently a yellow gizmo attached to the back of the speedometer. Apparently it gets dirty and gives up the ghost. I'm going to try to give it a clean, and hopefully that will improve matters.

This may be what's wrong with yours - see what works and what doesn't. This should narrow down the possibilities as to which sensor has gone U/S.


Ali Cabrio

PS - the vacuum pipe on mine was a hard white plastic pipe, branching off a plastic junction piece stuck into the inlet manifold. What piping you use for this is non-critical, just as long as it wont melt on the top of the engine.

The upshift light doesn't need the switch on the gearbox. It will light up even in neutral when revving the engine. The gearbox switch tells the consumption/econometer/MPG meter that?s its in 5th. It should only work in 5th.

If yours works in all gears I think someone?s shorted the connection.
 :dontknow:

The upshift light needs the black round thingy plumbed into the vacuum pipe near the dizzy.

1800 - Yes, someone has shorted the connection.

Me  

I don't have the switch on the gearbox that would tell the econometer/gear shift indicator that fifth gear is engaged. Somebody replaced either the gearbox or the dash at some point in my Golf's past. So I either disconnect the switch wires (and get the upshift light all the time), or reconnect them (and get the econometer needle all the time). I prefer the wagging finger of the needle telling me how much fossil fuel is being sucked in, at the moment anyway.

I have sourced a basic toggle switch and will at some point soon get round to mounting it on the dash so that I can toggle manually between the two. A previous attempt to do this resulted in a short, lots of smoke and burnt fingers

 

I believe the digital econometer (on the MFA) is supposed to work irrespective of the upshift light/analogue econometer. Anyone know otherwise?


Ali Cabrio

Ahhh so the gearbox switch wires effect the upshift light by toggling between upshift light and econometer. Telling upshift light not to work in 5th and then when in 5th your econometer needle will work.

Has someone replaced your gear box with a non-MFA version that just has a normal screw-in reverse light switch instead of the black plastic MFA jobbie?

Yes I think MFA MPG works independently.

It looks like the gearbox has been replaced.

Or they've replaced the whole engine

The car came with an MOT certificate and zero receipts.. nada, zilch, none.

I'd like to think I've got something on the car (gearbox/engine) that's in slightly better nick than the rest of it - but judging by the lack of fifth gear switch on the gearbox, it's older than the rest of the car!!!  :roll:

There is a switch for the reverse light, and it works (at the moment). The fifth gear switch is just a make/break contact - but it toggles between upshift or econometer as you say.

I'm getting round to connecting a switch to it, but having re-asembled the dash I'm a bit reluctant to take the whole thing apart just to get a couple of wires through the bulkhead.

I mis-read the wiring diagrams (and halfrauds switch) the first time I tried and shorted the battery - LOOOOOADS of smoke. Wont be doing that again.

Fun and games. This weekend I will mostly be trying to remove the inlet and exhaust manifolds, preparatory to removing the head, in order to replace the head gasket. MPG meters are not really a priority at the mo….

Ali Cabrio