Chipped for fuel economy?

[Rusty]

I can confirm that I'm getting over a 2mpg improvement using a standard Homefries.

That's based on comparing consumption on over 20,000 miles before Homefries and doing the same over 15,000 miles on Homefries where I'm getting 28.6mpg.

This is real mpg based on brimfull to brimfull, not using the on board display. Also all on 95 RON unleaded

John

28.6mpg... what the phook!

I get 15-20 but then I spend most of my time performance testing or having fun

[Rusty]

Can someone supply a new chip for my brain to remap it from Gran Turismo mode to Grandad mode, that should improve MPG a lot... Liking the idea of mechanical boost to limit fuel / boost use but then the 1.9 Bar spring in the pipeline will make that null and void

[urS6Tom]

Here's a thought - would you get exactly the same result as the multimap setup by implementing a switch to turn the WGFV fuse on and off?

[dest]

Why not just be a bit lighter on the loud pedal? Cheapest and easiest mod ever lol!

[urS6Tom]

Why not just be a bit lighter on the loud pedal? Cheapest and easiest mod ever lol!

Just thinking about setting the cruise control and sitting at 80mph on the motorway. Would there be much difference in mpg with WGFV disconnected? Presumably you'd normally have more than 0.4 at 80mph?

[S2central.net]

Turbo 101 - when cruising at steady speed - you will have NEGATIVE boost - vacuum in other words. The ECU runs closed loop with lambda feedback to target AFR of 14.7 when cruising. You can use wideband lambda probes with controllers that can fake a signal into the ECU so as to fool it into running leaner or richer than 14.7 - obviously this needs to be done carefully so as not to run dangerously lean in closed loop mode.

There are guys who have done this trick to good effect - running slightly leaner does save fuel alright. At WOT, the ECU is programmed to ignore the lambda sensor and runs directly from the fuel maps so it still gets correctly rich mixture under heaviest load so as to promote performance and reduce chances of knock.

My trick on the ECU to limit boost to 0.4bar only has beneficial MPG when accelerating thru gears as with lower boost, the engine consumes less fuel. It has no benefit when cruising at 70 on the mway.

[urS6Tom]

Turbo 101 - when cruising at steady speed - you will have NEGATIVE boost - vacuum in other words. The ECU runs closed loop with lambda feedback to target AFR of 14.7 when cruising. You can use wideband lambda probes with controllers that can fake a signal into the ECU so as to fool it into running leaner or richer than 14.7 - obviously this needs to be done carefully so as not to run dangerously lean in closed loop mode.

There are guys who have done this trick to good effect - running slightly leaner does save fuel alright. At WOT, the ECU is programmed to ignore the lambda sensor and runs directly from the fuel maps so it still gets correctly rich mixture under heaviest load so as to promote performance and reduce chances of knock.

My trick on the ECU to limit boost to 0.4bar only has beneficial MPG when accelerating thru gears as with lower boost, the engine consumes less fuel. It has no benefit when cruising at 70 on the mway.

Aha. Thanks for that Paul.

Talking of Turbo 101 - can anyone recommend a good book or website that covers basics such as this?

cheers,
Tom

[mcandmar]

Steady cruise with positive boost will be over 100mph, with an 80mph cruise speed the intake vacuum is roughly the same as idle. Funny the things you notice with cruise control and a boost gauge

I use the boost gauge and my right foot to keep it just below .5bar around the city, all those little bursts to 1bar+ is what uses up the most fuel.