TPS based AFR map for better mileage (?)
#1
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Hey,
I started testing this AFR map in order to improve my 15mpg...
This map is great, it will not shoot 11.5 when only "accidentally" getting in to low-mid boost for a sec or two, it will go for 14.6, only near and @ WOT it will go to 11.5.
My question:
Running 7.5psi of boost for a few seconds at 14.6:1 AFR (knock free) good ? bad ? do ? don't do ?
The traditional AFR map (MAP based) will go to 13.5-12.5-11.5 anywhere from 100kpa and up... so 150kpa will be 11.5, even if it was for a second or two - wasting fuel ?
Thanks !
I started testing this AFR map in order to improve my 15mpg...
This map is great, it will not shoot 11.5 when only "accidentally" getting in to low-mid boost for a sec or two, it will go for 14.6, only near and @ WOT it will go to 11.5.
My question:
Running 7.5psi of boost for a few seconds at 14.6:1 AFR (knock free) good ? bad ? do ? don't do ?
The traditional AFR map (MAP based) will go to 13.5-12.5-11.5 anywhere from 100kpa and up... so 150kpa will be 11.5, even if it was for a second or two - wasting fuel ?
Thanks !
![](https://www.miataturbo.net/attachments/megasquirt-18/150487d1442732453-tps-based-afr-map-better-mileage-capture.png)
#2
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I've run 14:1 at 100kPa, 13:1 at 150kPa with my GT3271 setup. This actually made it spool a lot better and drive much better. It still went to 11.0 once it got around 200kPa, and high 10's by 250kPa.
Whether or not you can Pull off running lean at low boost really depends on the setup. Copmression, AITs, fuel octane, how safe/conservative/aggressive/ignorant your tune is, how equal your injectors are, is the motor carboned up and old, AITs, and the list goes on a lot.
If you don't know what you are doing, don't try to run lean in boost. It's a fantastic way to break stuff fast.
For reference with my SC setup on 93 octane, it made better power by throwing the fuel at it FAST and adding. I was running 11.0:1 by 150kPa but this allowed me to run 2-3 degrees more timing and it really made a difference in low end torque. If I ran 14:1 I had to pull 3-4 degrees to get it to not knock, and then it was slower. No driveability/spool benefit (no turbo) so it stays rich in boost now.
Also you need to make it load based, not TPS based.
Whether or not you can Pull off running lean at low boost really depends on the setup. Copmression, AITs, fuel octane, how safe/conservative/aggressive/ignorant your tune is, how equal your injectors are, is the motor carboned up and old, AITs, and the list goes on a lot.
If you don't know what you are doing, don't try to run lean in boost. It's a fantastic way to break stuff fast.
For reference with my SC setup on 93 octane, it made better power by throwing the fuel at it FAST and adding. I was running 11.0:1 by 150kPa but this allowed me to run 2-3 degrees more timing and it really made a difference in low end torque. If I ran 14:1 I had to pull 3-4 degrees to get it to not knock, and then it was slower. No driveability/spool benefit (no turbo) so it stays rich in boost now.
Also you need to make it load based, not TPS based.
#6
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I try to get better mileage, it looks like a good way, TPS based AFR.
I run a very small turbo (53mm compressor wheel), every tip on the gas pedal will get me into boost, and then run 11.5...
With this table I can get in to low-mid boost for a few secs and run 14.6 - saving fuel.. (?) - it happens a lot... (maybe I need a bigger turbo - 60mm)
I run a very small turbo (53mm compressor wheel), every tip on the gas pedal will get me into boost, and then run 11.5...
With this table I can get in to low-mid boost for a few secs and run 14.6 - saving fuel.. (?) - it happens a lot... (maybe I need a bigger turbo - 60mm)
Last edited by elior77; 09-20-2015 at 03:50 AM.
#7
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I try to get better mileage, it looks like a good way, TPS based AFR.
I run a very small turbo (53mm compressor wheel), every tip on the gas paddle will get me into boost, and then run 11.5...
With this table I can get in to low-mid boost for a few secs and run 14.6 - saving fuel.. (?) - it happen a lot... (maybe I need a bigger turbo - 60mm)
I run a very small turbo (53mm compressor wheel), every tip on the gas paddle will get me into boost, and then run 11.5...
With this table I can get in to low-mid boost for a few secs and run 14.6 - saving fuel.. (?) - it happen a lot... (maybe I need a bigger turbo - 60mm)
MS3 has time based fuel enrichment, you could play with that to find a compromise.
#13
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Just a thought experiment. I'd be interested to see what your timing is at in cruise.
#17
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TPS based seems to work great, when you leave a stoplight or when you accelerating mildly and get in to 110-150kpa for a few seconds, afr will not deep to 11.5 it will stay at 14.6, but when I WOT or near WOT I get to 11.5.
I cruise @ 38deg that helped get my EGT back to normal, if I get 15mpg I guess I must tune and lean where possible.
All is knock tested and cleared.
I would love to know how to get 30-35mpg (!!)
I run a small turbo (TD04-13C), 460cc injectors, 6spd trany, 4.11 lsd dif, TOYO R1R 205/55/15 tires.
I cruise @ 38deg that helped get my EGT back to normal, if I get 15mpg I guess I must tune and lean where possible.
All is knock tested and cleared.
I would love to know how to get 30-35mpg (!!)
I run a small turbo (TD04-13C), 460cc injectors, 6spd trany, 4.11 lsd dif, TOYO R1R 205/55/15 tires.