Fuel Economy Tuning Ideas

[onecamaro1]

Well, that didn't work. I set it and the commanded afr was spot on, but the actual didn't budge.

[onecamaro1]

I'm going to recalibrate the VE and MAF for 16:1 and see if that works.

[RedWS6 00]

Make the fuel trims never come on by commandin open loop only. To do this you wack up the temps of closed loop so it never occurs.

There is a table in HP Tiuners call Eq Ratio. I've got it to command .9 at low maps, therefore running lean. It runs about stoch around 50kpa, and above i go a little richer to meet PE.

I've been running the car like this for a long time, no harm done, how ever I have removed the cats.

Aussie cars can run Lean Cruise in their PCM, its not enabled on US versions. We can try to emulate lean cruise by enabling Open loop EQ ratio.

Also enable DFCO that save a bit of fuel. I'v also turned my idle down as can sit in fraffic for 10mins per day so this also saves fuel. My idle is 500RPM with no AC, with Ac on it 550RPM. You wil have ot play with the IAC points and timing, but it can be done.

[onecamaro1]

Ok i'll try that. i tried to go to 600 idle, but as i released the clutch, it seemed to want to stall out if you don't do it smoothly. dfco is good, and i'll try eq in about an hour. i got 290 this tank. before the o2 millivolt trick by EC i was getting a solid 250.

[onecamaro1]

Thats all done and the car seems to not bucking, but the MPG guage says 17.
Before all of this, it said 21 on the full trip. i'll ride the tank out like this and check the actual MPG. I'm at 1/2 tank @125 miles, which is correct for the 21.

[onecamaro1]

Here is what i've done.

[samgm2]

All that will do is increase the reaction rate and create a more irreversible reaction that will lower your efficiency.

Yes, you will be as lean as you can be, but your reaction rate will go also go up.

The more reversible a reaction is, the more efficient power extraction is.

You have to retard timing significantly to lower the reaction rate. At that point you can run 16:1 - 18:1 - 20:1, etc. until you reach a point where all the fuel is reacting. The O2 sensor may not work well for this type of reaction. It will show lean but in reality you will have some uncombusted fuel.

Maximum power will fall but efficiency will go up.

The idea is to approximate the diesel cycle.

Sam

I'm going to recalibrate the VE and MAF for 16:1 and see if that works.

[onecamaro1]

Ok, i left stoich alone at 14.73 and went OLSD so i could just work off the EQ table.
Everything is where i want it now, 20-70 map=.9206, <70 map=1.0.
This is working perfectly, but i still need to work the ve 1 more time as my idle AFR is 15.5 and should be 16.0.
I spend a lot of time watching my IFR to keep it as low as possible, 2.5-3.0 is where it seems best at cruise speed.
I drive 350 miles a week, and i am trying my best to do it one one tank. I was at 290 last tank before OL, and i seem to be on track for 300-310 with OL (all of this is city and hiway mix).

[n0dih]

Can HPT on any of the GM cars/trucks keep TCC locked on Decel like my LT1 tuner can?

If the rear axle is setup properly (tight backlash), then this is a sweet thing to use, gives much more feel ike a stickshift. With a loose axle you will hate it, makes the car very clunky. But a tight backlash it is almost imperceptable, other than the feel like you just backed off the gas in a stick and left the clutch fully engaged.

The nice thing coupled with DFCO and plan for long decels, allows for DFCO to not turn back off for typically another 10 more mph lower. With this and no other changes, I am able to see up to around a 0.4-0.7 mph increase. This is based on averages over around 5K miles. Not guess numbers. I drive around 35K to 40K a year, and keep excellent mpg records, as well as tuning changes I make. This is one that does help, but not for everyone.

If anyone has any negative aspects of this, please let me know.

[MNR-0]

Can HPT on any of the GM cars/trucks keep TCC locked on Decel like my LT1 tuner can?

If the rear axle is setup properly (tight backlash), then this is a sweet thing to use, gives much more feel ike a stickshift. With a loose axle you will hate it, makes the car very clunky. But a tight backlash it is almost imperceptable, other than the feel like you just backed off the gas in a stick and left the clutch fully engaged.

The nice thing coupled with DFCO and plan for long decels, allows for DFCO to not turn back off for typically another 10 more mph lower. With this and no other changes, I am able to see up to around a 0.4-0.7 mph increase. This is based on averages over around 5K miles. Not guess numbers. I drive around 35K to 40K a year, and keep excellent mpg records, as well as tuning changes I make. This is one that does help, but not for everyone.

If anyone has any negative aspects of this, please let me know.

HPT can already do this. Lower your release speed for the TCC at 0% TPS.

[n0dih]

At least on the LT1, the PCM overrides anyway and at rapid release of TPS and release of TPS (2 switches), it disengages the TCC despite what the TCC tables are. If GM got rid of this, then that is good news.

[Crash41301]

sens.112 is extremely important....Injector Pulse Width in milleseconds

if its not working then you are missing something while logging
must log all of those parameters...

I have an updated one now too..takes into account IAT and ECT..

[SENS.20]/(([PID.6210]*0.132276)*[SENS.112]*[SENS.70]*8/(6175*(((([SENS.11]+[sens.10])/2)+273.15)/299.8167)))

this should get you MPG..and should compensate a little for fuel temperature a little bit..cause fuel weighs different amounts at different temperatures

seems to be accurate in my car...
works perfect..last 4 tanks have been all within .5 of dead on for me...

basically its
[MPH]/(([Injector Flow Rate]*0.132276)*[InjectorPulse Width]*[RPM]*8/(6175*(((([IAT]+[ECT])/2)+273.15)/299.8167)))

with everything converted so that the units match appropriately

You Must Log:
Vehicle SPEED
Injector Flow Rate
Injector Pulse Width
Engine SPEED
IAT
ECT

I cant find Injector Pulse width. Help? Is that the only one I am missing? I see pulse width for bank 1 and bank 2, but no just "injector pulse width"?

[EC_Tune]

You must log RPM & IPW and then you can place it in the Chart area or make a histogram. Oh, you can log it on the table view but why when you can chart it or make a histogram for it without using up valuable table space.

[Crash41301]

You must log RPM & IPW and then you can place it in the Chart area or make a histogram. Oh, you can log it on the table view but why when you can chart it or make a histogram for it without using up valuable table space.

Maybe I'm just dumb, but you can provide me the exact name, and how to get to "Injector pulse width". The only injector pulse width's I see are specific for Bank 1 and Bank 2, yet when I read this it seems like there is an average of the two somewhere? Do I need to make a custom PID with (Bank 1 + Bank 2) / 2 to get the pulsewidth?

[EC_Tune]

Nope, you can just log one of them. If you are logging both it will average them to get combined IDC.

[Super73]

I have been playing with a MPG PID.. Man my 63 truck gets real bad mileage.. On the freeway I am getting about 9.5mpg based on Scotts most recent PID. I'm trying to figure out why it is soooo bad. My AF bounces between 14.5 and very low 15 during freeway cruise. L-trims are all in line. Here is the set up:

63 P/U
Forged bottom end
Stock LS6 heads
XER 223/228 108/108
Stock LS6 intake
Stock TB
Stock pulley
Stock 4L80E (stock verter)
Power steering (no AC)
Edelbrock 1 3/4 - 1 7/8
3" X-pipe
8.5" 10bolt with 3.73's
275/50/15


Tune: http://73-ls1.com/63truck/8_26_07.hpt
Config File: http://73-ls1.com/63truck/MPG_Cruise.cfg
Log: http://73-ls1.com/63truck/Back.hpl


Please ignore the Wideband on this log. My LC-1 needs frequent free air testing and last night it decided to be a pain. Any ideas on the MPG?

[EC_Tune]

4L80E will suck up a *bit* more power than a 4L60E with every thing else remaining the same. What does your wideband say the AFR is at cruise?

[Super73]

Bounces between 14.5x and low 15.2

[EC_Tune]

Hmm. Bouncing doesn't sound good to me.
Slow rolling sounds better. Might be a proportional fueling issue: loop parameters might be driving the injectors +/- too far to find stoch at cruise. Might want to decrease the Closed Loop Proportional Airflow Mode values a bit if you have larger than stock injectors in your ride.

[Super73]

I guess mentioning the injector size is always a good thing.. They are SVO 30's with the adjustable regulator set to 58lbs. I have adjusted the IFR but not the CLPAM.. Any suggestion on where to start.. IE 5% 10% 20%