Hello all,
I recently purchased a mk6 GTI and am considering doing a stage 1 tune. As it will be my daily driver, I'm very interested in fuel economy. Has anyone shown any fuel economy gains with a stage 1?
Some tunes do in fact claim you will see increased mpg. I think unitronic is one of them. And look, that is probably bang on at the low end of the rev range, where you are basically driving a regular 4 cylinder and totally out of boost.
But the minute you start compressing air ie in boost, you are going to burn more fuel. You simply must increase the amount of fuel sprayed into the cylinders to match the increase in oxygen content of the compressed gas. And since all tunes achieve more power by raising boost levels from the stock 6-8 psi all the way to the low 20s it follows that stage1 or stage 2 tunes should decrease your mpg
But the minute you start compressing air ie in boost, you are going to burn more fuel. You simply must increase the amount of fuel sprayed into the cylinders to match the increase in oxygen content of the compressed gas. And since all tunes achieve more power by raising boost levels from the stock 6-8 psi all the way to the low 20s it follows that stage1 or stage 2 tunes should decrease your mpg
The only explanation I heard once was that the factory maps run rich to fight pre-ignition/detonation, the tuners lean it out so it then runs better mileage out of the boost and when you get into the higher boost it requests more fuel for the ratio it's but the same-ish as the factory rich mixture. Basically, stating the factory map requests enough fuel to cover more boost. Never saw any proof or documentation though, never really cared LOL Car felt amazing at Stg1 and Stg2 put the cherry on top, and there's filling stations all over for a quick top off.
Just as a follow up, I was averaging around 27 mpg before the stage 1, and I'm now averaging 29 mpg after the tune. If I'm super gentle with my driving, I can easily top 35 mpg in town. So I can definitely tell my wife that the tune will pay for itself, haha!