I managed to get hold of a 'tuning box' for the Golf this week, that unlike any of the others I've seen, has a bit more to it than a matchbox size box with a transistor and a variable resistor.
The main thing that made my buy it, is it has a vacuum feed that it draws from the manifold, leading me to believe that it would be doing more than lying to the pump... it would actually be tweaking the fuelling according to what the engine was being asked to do.
Anyway... I spent this morning changing the oil and then fitting this.
Not quite the five minute patch in and out job of the other box, as you have to patch it into the main inlet to ECU vacuum feed.
Initially I was disappointed, as the car didn't feel nearly as responsive.
However... having given it a good session of italian tuning up and down the local bypass, trying the car with this, and then without this new box, you can definitely feel the difference.
Net result is... it doesn't feel quite as responsive off the mark, but the power is a lot more progressive and more of a curve that matches that of the car in standard form.
More importantly, it's done away with the engine judder I was experiencing with the other box between 1400 and 1600rpm in fifth, (which equates to just over 40mph) and it's also done away with the excessive sooting which went hand in hand with the other box if you wanted the car to have a noticable power increase over the standard set up.
Net result is what I was hoping to achieve by making the other box something I could kick in and out with a switch - I now have the smoother progressive power delivery of the standard car, with a lot more mid range when I need it.
All in all, I'm impressed - where as the other box just messes with the pumps mind by way of set in stone adjustments of the parameters it relies on to determine the fuelling needed and which it feeds to the pump by way of two loops between four of the pins going into the pump, this box has a direct feed to four of the pins, knocking out the feed from the standard ECU, meaning I now have a proper remap.
Never seen one before, anyway... I suspect it would have cost rather more than =A342 new. ;-)
--=20 JackH