Upgrade the pishy polo coil. The mk3 polo has an amp and coil built into one. Its crap, do not let anyone tell you different. Although its fine to run most polo's it couldn't run the T at all. So I did this mod and it makes the world of difference. Since then I have done it to my G40 and the GT and it helps greatly! SO...
Go find a late mk2 golf GTI or Passat of similar spec with DIGIFANT electronic fuel injection. The coil and amp are separate on these things so you need to unbolt the coil(should have a green sticker on it, and note which side is which in terms of positive and negative(red and black!!))keep the bracket and the bolts, and cut out the wiring loom between the coil and the amp. The amp looks like a little ECU(about the size of 2 matchboxes) that is bolted to the main ecu metal mounting plate(on the golfs anyway) using 2 self tapping screws. The Amp has a 6 way plug that goes to a loom that goes to the coil..... cut this out with as much cable as possible, you'll need it(only 4 pins of the 6 pin multiplug are used by the way!).
When the time comes to fit it to the polo, its pretty simple. The coil goes where the polo coil goes. easy, the amp I normally mount up in the bulkhead near the ECU and have the loom run down the side to the coil under the washer bottle.
The wires going to the coil in the polo now go to the amp with the exception of the black wire which goes to the negative side of the coil. The only mismatched colour as I remember is that the black and green from the polo goes to the solid green on the amp. the red from the amp goes to the coil as it did in the donor car. Solder them all up and away you go....
Polo MPGS: When running the digifant system in the turbo 20-25ish, got 17 once when running in diagnostic mode!!(blue temp sender disconnected).
In the G40 (chip, toothed belt pulleys and full blend) I do not get below 30, if I'm gentle 34, most I've ever had is 39.
GT: I get 37 all the time and I screw the nuts off it all the time! I can get above 40 if I actually try...
I've also heard of duff purge valves causing MPG problems too...
All this is assuming you have a decent Lambda sensor, which there are articles on testing on Club Polo If not get new ones from a bosch agent, half the price of VAG and are identical parts!
MORE ON COIL MOD…
As you can see, its a bit of as mess! If you have the amp and loom from the mk2 golf gti you will have 4 wires from the amp. on the pic this is coming from underneath the screen wash bottle as I have my coil up next to the ECU.
Amp wires go to:
Green - Black/green from engine wiring loom(hooked round my pinkie) previously on top of old coil pack
Red - Positive side of coil
Black - negative side of coil
Brown/white - goes to brown from engine loom (that goes to the multiplug next to the coil)
OK, so here’s where the wires from the top of the coil go just to be clear:
Black/green - goes to green on amp
Black - goes to Negative side on coil
Brown - to brown white on amp
Originally posted on G40 Club by Mark Hunter