TPS based AFR map for better mileage (?)
2 Attachment(s)
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 ! https://www.miataturbo.net/attachmen...7&d=1442732453 |
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. |
If it does not knock, could be other damage I'm not aware of ?
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1 Attachment(s)
Actually, just checked, this is how the car was tuned on pump gas before I switched to E85.
https://www.miataturbo.net/attachmen...ine=1442733195 If you wanted to modify that for turboage, I'd change 11.0 to 11.5, and have it to go 11.5 by whatever your target boost pressure is, interpolate between of course. |
Originally Posted by elior77
(Post 1268163)
If it does not knock, could be other damage I'm not aware of ?
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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) |
Originally Posted by elior77
(Post 1268166)
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) MS3 has time based fuel enrichment, you could play with that to find a compromise. |
You need an MS3, which supports blending AFR tables 1 and 2, based on TPS.
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Whoa, didn't know it could do that. It's funny cause I've been getting about 16 mpg now, and was thinking about how to get better mileage
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You don't need tps based Afr. You need a not shitty tune. I hit 32mpg on my last trip to California. Don't be a shitry driver. I'll post my AFR map soonish.
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Actually op, why are you running 11.5 at 100 kpa? I'm running 12.8 or so at 100 kpa, and that's still too rich. Keep in mind 100 kpa is just starting to become boost
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<p>I leaned out my cruise range (40-50 kpa & 3k-4k rpm) to nearly 16:1. I was getting ~25 mpg average. This was also with RX7 550cc injectors. I bet with the gt500's I have now I'd get much better mileage. </p>
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Originally Posted by aidandj
(Post 1268193)
You don't need tps based Afr. You need a not shitty tune. I hit 32mpg on my last trip to California. Don't be a shitry driver. I'll post my AFR map soonish.
Just a thought experiment. I'd be interested to see what your timing is at in cruise. |
Yeah.... you just need to tune and maybe change your driving habits a little if you're worried about MPG on a turbo miata.
My last turbo Miata did a best tank of 35.3mpg running a DIYPNP. Typically averaged 33mpg highway, 31mpg combined. |
how about just don't cruise leaner than 15.5 AFR?
that map posted above (i havent read anything) would suck dick holes for MPGs. |
Originally Posted by aidandj
(Post 1268193)
You don't need tps based Afr. You need a not shitty tune. I hit 32mpg on my last trip to California. Don't be a shitry driver. I'll post my AFR map soonish.
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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. |
why not always go for MBT
when you are cruising, you need ... torque The farther you throttle is closed for that torque the less fuel you consume That's my theory, but I could be wrong |
150kpa @ 14.6:1 AFRs, what could possibly go wrong?
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1 Attachment(s)
Can create AFR targets based on load and RPM. Chooses to use TPS% instead.
https://www.miataturbo.net/attachmen...ine=1442925499 |
for a second or two without knock
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There's no reason to see AFRs like that under boost. Ever. You also said "a few seconds."
And "accelerating mildly." None of these things add up, and none of them make it ok to target 14.6psi at 150kpa. |
Originally Posted by concealer404
(Post 1268617)
There's no reason to see AFRs like that under boost. Ever.
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Originally Posted by Braineack
(Post 1268618)
Said no OE turbo car trying to pass strict emissions standards. ever.
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All in all I understand I need lean as possible (knock free, normal EGT) cruise with 35-40deg.
Leaner map all around will give better mileage and I can go to 13.5~ in transit boost, WOT would still be 11.5. I think that's my plan for how to get better (normal) mileage. Thanks. |
1 Attachment(s)
i dont understand why you can't just tune like this:
https://www.miataturbo.net/attachmen...ine=1442926576 |
I understand that tps based and leaner afr map would be very much the same.
Thanks for the map Brain. (I'll try it too) |
Cruise is not 150kpa though. I never had ridiculous AFRs like that in my map and i broke 30mpg every time.
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Where did you read that cruise is 150kpa ?
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<p>This is my 32mpg AFR map.</p><p><img src="https://cimg5.ibsrv.net/gimg/www.miataturbo.net-vbulletin/514x350/80-m5zsnhq_b70eaac4cb2fcbb0dca9afaf407d6af1f80c1fd7.p ng" title="" /><br /><br /> </p><p>I have seen @Ben talk about cruising even leaner, with lots of advance.</p>
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Brain,
Why not carry the 16.0 value to the cells below down to 30 kpa? |
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