fuel efficiency tuning

[Maglin]

If you are after sole MPG then don't run e85. I've gotten very good results running 15.7:1 and around 38* of timing. but that was in 5th doing 75mph. You'll want to change the OL set points for the TPS% and airflow. When you are fine tuning it's definitly best to be a passenger, and have the driver set the cruise control. Use your logger and for constant cruise monitor your ipw and see if your timing change makes it go down. Once you see your ipw go up after increasing timing advance then back if off at least 3*. You will also want to go in 1* incraments. (this is assuming you have this ability) If you are just using the AFC and doing fuel tuning then it's a 2 way battle. As you lean it out you are also increasing timing. You have to remember that the ecu interpolates between cells. You also want to make sure you have the PKelim code in their so you don't pull timing with knock.

For stop and go you can do this alone while you drive and actually it's best for you to do the driving. Log for a set a to b then b to a trip for one log. Again using your ipw get an mean average. Then start advance your timing. Here I would go in 3* incraments until I see a ipw raise then back off in 1* incraments until I see an ipw increase. All this is assuming that your car is staying in closed loop and thus maintaining your 1.15 lamba. (sp) Why it's important to change your OL set points. I can also guarantee that doing this will make the car feel more lazy out of the hole until it see's OL and even then it might have a small power hole on the bottom end.

If you follow this advise I can 100% guarantee you will get the best mpg you can. And if you did use E85 you would probably see better MPD (mile per dollor). I personally love e85. I plan on running it on a staged injection setup. It's just cheap 106 octane and burns very clean.

 

[pneumo]

I used to have one of those 'little holes' in the power delivery when the car was at it's leanest. I fixed it by increasing Accel enrichment at the affected rpm. Now the A/F ratio jumps richer at the first twitch of the throttle.

A general rule that helps me get great mpg is to set the A/F ratio leanest at steady, light throttle cruise, and don't try to stay lean when it's time to make power.

 

[jrohner]

E85 - I get 17-19 in town, 20-23 on the highway. I run around 11.5:1 AFR (which is about 17.25:1 gas AFR). I run my wideband to my ECU and just adjust my wideband output to run as lean as I want. My cruise timing is within a couple degrees of the stock 2g map. When I installed the BC272 cams, I think it seemed to hurt my everyday mileage slightly (because of the extra hp - I'm on the throttle a lot), but the highway mileage was unchanged. When I was running FWD mode for a while because of a tranny issue, I got close to 20mpg in my everyday driving, since I couldn't get on the throttle til at least 3rd gear.

Back when I was running gas (91), AFC tuning, and the stock o2 to the ECU, I got around 18-19 in town and up to 25 or 26 on the highway, so not much different than now.

 

[snooopy365]

wow 17.25 sounds very lean to me? whats your exhaust gas temperatur doing?

thx Maglin, for your clean good advice
And like I wrote, I`m Using S-AFC and a Eprom Simulator (it broken right now... waiting to get it back).
OL Points aren`t that bad, I`m @ lambda 1.15 about 90% off the time.
And of course lambda for OL is ~ 0.75-0.8!

I`m just want to max out the capacity of E85... its not the money thats my problem, its the small range per tank that pisses me off