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awptickes · 07-16-2008, 11:27 AM

This is a common question. It really doesn't correspond to the stoicheometric ratio, as much as you'd think. Many people new to digital tuning, aren't real familier with the digital accuracy we now enjoy (are cursed by?). What number should you tune to? Well, it depends on what you do, and how pissed off you are about gas prices, and also how much crap (ethanol) they put into your gasoline. This is assuming 0% ethanol. For every 10% ethanol, subtract 0.5 points.

Normally, with a NA engine, you want a slightly lean mixture at part throttle (15.0-15.5 :1) and slightly rich at WOT (12.5:1). This will keep you safe, and give you plenty of power. Normally, you don't want to stray more than about 2 points away from 14.7, and you'll stay safe.

Agressive: while still NA, at part throttle, low load, you want (14.7-14.5 :1), then at high load/WOT, 11.5:1. This will use a lot of fuel, but it'll give you lots of torque and power.

Low Fuel Usage: If you're like me, and you drive about 100 miles a day, at 100mph average sustained speed, fuel efficency is a priority. This is where you lean out the tables, and advance timing, but we won't get into timing. NA, part throttle/low load, (16.0-16.5 :1) then at WOT, no richer than 12.5:1. Personally, I was running 17:1 part, and 14.0:1 WOT. Not much power, but better FE. Alternatively, you could just lean out the part throttle, and try not to stomp on it.

Here's a chart to get a good idea:

Here's a chart for those of us who run E10:

Enjoy. Happy tuning.

TurboMirage · 07-16-2008, 12:13 PM

most of the US is now up to 10% ethanol though...

awptickes · 07-16-2008, 01:21 PM

Just subtract .5 points from every number for every 10% ethanol contained in your fuel.

TurboMirage · 07-16-2008, 03:16 PM

can you just provide us a new diagram?

awptickes · 07-16-2008, 05:12 PM

Quote:

Originally Posted by TurboMirage

can you just provide us a new diagram?

Sure thing. I'll do that tomorrow morning when I get into work. Now it's sleepy time.

TurboMirage · 07-16-2008, 06:18 PM

awptickes · 07-17-2008, 02:15 AM

Updated with E10 AFR chart.

Luis998 · 07-17-2008, 02:18 AM

Thanks for the write-up! I'd rep you but yeah, I must spread it around more.

07-16-2008, 11:27 AM	#1
awptickes Von Europa Join Date: Aug 2007 Location: Bel Air, MD Age: 20 Posts: 2,001 iTrader: 5 / 100% Ride: 1999 Civic EJ9, 2003 Civic EX Coupé Rep Power: 55	Tuning to AFR This is a common question. It really doesn't correspond to the stoicheometric ratio, as much as you'd think. Many people new to digital tuning, aren't real familier with the digital accuracy we now enjoy (are cursed by?). What number should you tune to? Well, it depends on what you do, and how pissed off you are about gas prices, and also how much crap (ethanol) they put into your gasoline. This is assuming 0% ethanol. For every 10% ethanol, subtract 0.5 points. Normally, with a NA engine, you want a slightly lean mixture at part throttle (15.0-15.5 :1) and slightly rich at WOT (12.5:1). This will keep you safe, and give you plenty of power. Normally, you don't want to stray more than about 2 points away from 14.7, and you'll stay safe. Agressive: while still NA, at part throttle, low load, you want (14.7-14.5 :1), then at high load/WOT, 11.5:1. This will use a lot of fuel, but it'll give you lots of torque and power. Low Fuel Usage: If you're like me, and you drive about 100 miles a day, at 100mph average sustained speed, fuel efficency is a priority. This is where you lean out the tables, and advance timing, but we won't get into timing. NA, part throttle/low load, (16.0-16.5 :1) then at WOT, no richer than 12.5:1. Personally, I was running 17:1 part, and 14.0:1 WOT. Not much power, but better FE. Alternatively, you could just lean out the part throttle, and try not to stomp on it. Here's a chart to get a good idea: Here's a chart for those of us who run E10: Enjoy. Happy tuning. Attached Thumbnails __________________ DIY/Howto HID Projector retrofit Last edited by awptickes; 07-17-2008 at 02:15 AM. Reason: added 10% ethanol chart

07-16-2008, 12:13 PM	#2
TurboMirage Running on two cylinders Join Date: May 2003 Location: Southbridge, MA Age: 24 Posts: 16,174 iTrader: 0 / 0% Ride: 2000 Mitsubishi Lancer RPW E5 Coupe Rep Power: 219	most of the US is now up to 10% ethanol though... __________________ Home of the RPW built 2000 Lancer CC Coupe. See what is done to the Little EVO5

07-16-2008, 01:21 PM	#3
awptickes Von Europa Join Date: Aug 2007 Location: Bel Air, MD Age: 20 Posts: 2,001 iTrader: 5 / 100% Ride: 1999 Civic EJ9, 2003 Civic EX Coupé Rep Power: 55	Just subtract .5 points from every number for every 10% ethanol contained in your fuel. __________________ DIY/Howto HID Projector retrofit

07-16-2008, 03:16 PM	#4
TurboMirage Running on two cylinders Join Date: May 2003 Location: Southbridge, MA Age: 24 Posts: 16,174 iTrader: 0 / 0% Ride: 2000 Mitsubishi Lancer RPW E5 Coupe Rep Power: 219	can you just provide us a new diagram? __________________ Home of the RPW built 2000 Lancer CC Coupe. See what is done to the Little EVO5

07-16-2008, 06:18 PM	#6
TurboMirage Running on two cylinders Join Date: May 2003 Location: Southbridge, MA Age: 24 Posts: 16,174 iTrader: 0 / 0% Ride: 2000 Mitsubishi Lancer RPW E5 Coupe Rep Power: 219	rep! __________________ Home of the RPW built 2000 Lancer CC Coupe. See what is done to the Little EVO5


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07-17-2008, 02:15 AM	#7
awptickes Von Europa Join Date: Aug 2007 Location: Bel Air, MD Age: 20 Posts: 2,001 iTrader: 5 / 100% Ride: 1999 Civic EJ9, 2003 Civic EX Coupé Rep Power: 55	Updated with E10 AFR chart. __________________ DIY/Howto HID Projector retrofit

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Tuning to AFR