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View Full Version : Ideas to tune in better mpg?



AdamRRT
September 27th, 2011, 06:19 AM
Just thinking that we can kick around ideas on how to save MPG with our tuning. Just toss out ideas to discuss. I've got a few:

- slightly reduce duration throughout the daily driven power range. At least for me, since with my slightly bigger tips a stock tune slightly hazes upon acceleration.

- reduce boost-dependent fuel enrichment at cruising RPMs.

- reduce pilot duration throughout - I'm thinking I'll do my pilot at 50% from idle to 900rpm, and reduce it to 25% from 900rpm to 1200rpm, 10% from 1200-1500rpm, then gone. Just a thought so that it'll still idle quietly and not sound like a piece of crap at parking lot speeds, phasing it out by 1700rpm.

- raise rail pressure slightly - like 10-20% - at lower RPM where it truly might be hindering atomization, but leave it alone at cruising RPM. I have experimented and found that FOR ME, the theoretical increased MPG from increased RP leading to better atomization is nothing more than a sales pitch. I think there's a point of diminishing returns with rail pressure, and IMHO the benefit of atomization seems to barely increase the higher we go. If it were better, we'd be running more pressure from the factory. Just my thoughts and EXPERIENCE. It's not worth the increased injector wear.

What other ideas do you guys have to try to reduce mpg?
Do you think that a less touchy throttle would help, so that you never command more fuel than intended? I think so, but others may disagree. My thought is it'll reduce the times and amounts by which you accidentally give it more pedal than needed.

olboyowl
September 27th, 2011, 08:07 AM
Just thinking that we can kick around ideas on how to save MPG with our tuning. Just toss out ideas to discuss. I've got a few:

- slightly reduce duration throughout the daily driven power range. At least for me, since with my slightly bigger tips a stock tune slightly hazes upon acceleration.

ive got mine just slightly higher then stock levels in the dd range (stock motor). mine lightly hazes on initial take off and clears right up.

- reduce boost-dependent fuel enrichment at cruising RPMs.

i have my fuel limiter, boost (F0502) table reworked to 35 psi and up to 3500 rpm. from 0 to 8.1 psi and up to 1823rpm, its set to under 40mm3. rich clued me in on this when i first started messin with efi live and had me adjust accordingly from there.

- reduce pilot duration throughout - I'm thinking I'll do my pilot at 50% from idle to 900rpm, and reduce it to 25% from 900rpm to 1200rpm, 10% from 1200-1500rpm, then gone. Just a thought so that it'll still idle quietly and not sound like a piece of crap at parking lot speeds, phasing it out by 1700rpm.

curious myself as to what u come up with on the earlier rpm percentages. i think after messing with the single injection event, you would have to add timing to make it work. andrew, iceman and les can hopefully add more input to this. like i said in the other thread, i just smoothed mine out and blended it down starting at 2000rpm and its completely gone by 2600.

- raise rail pressure slightly - like 10-20% - at lower RPM where it truly might be hindering atomization, but leave it alone at cruising RPM. I have experimented and found that FOR ME, the theoretical increased MPG from increased RP leading to better atomization is nothing more than a sales pitch. I think there's a point of diminishing returns with rail pressure, and IMHO the benefit of atomization seems to barely increase the higher we go. If it were better, we'd be running more pressure from the factory. Just my thoughts and EXPERIENCE. It's not worth the increased injector wear.

my fp is set at 70mpa at 55mm3 at 1000rpms and gradually climbs to 145mpa at 120mm3 at 2200rpms in the dd range. i have no smoke/haze during normal dd and not TOOO bad of a cloud when passing.

What other ideas do you guys have to try to reduce mpg?
Do you think that a less touchy throttle would help, so that you never command more fuel than intended? I think so, but others may disagree. My thought is it'll reduce the times and amounts by which you accidentally give it more pedal than needed.

i have my pedal position to desired fuel table modified also (again, thanks to rich for the help). andrew tried it on his truck and seemed to like it. works out good for me. i won't be able to do a decent mpg test till next friday. im pretty sure on a full tank of fuel, driving between 60-70 mph, it'll get well over 600 miles out of a full tank. hope this helps adam