ziobep

What's a safe Air to Fuel Ratio for naturally aspirated Scion tC?

Are 13's too high? Will it damage the car?

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ziobep

?????

ziobep

anyone know?

KINGxOFxSKA

Damn impatient...

jct

lol i must say so

engifineer

14.7:1 is a stoich ratio (perfect burn) for good fuel. For the fuels you normally get and normal driving conditions, you will see various numbers, but 13:1 isnt too lean by any means NA.

And you gave all of 2 minutes between each post.. give people time to actually read your posts

soros151

Actually for Best Mean Torque a Max of 13.5 is the theorical limit for N/A cars. You start at 12.8 thgen work u'r way up until the EGTs gets to the limit, then test the car at the street and the track and make adjusments. It is all dependant on the fuel u use, altitud and blha blha blha, more things. All this at WOT of course, at crusing speeds, 14.7 is okay.

engifineer

14.7 is the ratio at which a full, lower emission burn is happening with ideal fuel. Power isnt all that is in consideration in a fuel injection design.

soros151

He is of course asking for an AFR to tune, my logic tells me he is asking about how lean he can go when tuning. I'm telling him. Also, try to run 14.7AFR at 6,000 RPM for some time, then tell me what happens.

engifineer

I didnt take it he was tuning, he just asked what was safe, as if he was questioning what his stock setup was running.

soros151

That kind of tells me, he is looking into tuning.

ziobep

i had the car tuned with emanage blue to combat the supercharger reflash that was on the ecu after i took the supercharger off......... the shop tuned the car and my air fuels are about 13.2 is that bad? beacuse seems like when it gets really cold the car stalls on me....any help?

engifineer

Why? NA can mean stock as well as anything else. I have seen 3 people post up similar questions in forums because they first bought a wideband, scan tool, etc and thought thier stock numbers looked wrong. So it was a valid response to a non-specific question.

soros151

I think this does mean about tuning. About the car stalling when cold, that seems kinda weird. Any other mods to the car? is the 13.2 at WOT or at cruising?

ziobep

its at WOT..... i have intake, headers, exhaust, high flow cat, alternator pulley, water pump pulley , lightened crank pulley, emanage blue, stage 3 clutch and fidanza flywheel, and 255 walboro fuel pump..

ziobep

and sometimes revs a little at idle

Stripper

At WOT you want around 12.5:1 - 12.8:1
At idle you can have it anywhere from 14.7:1 - 15.5:1

If your on a chassis dyno and looking at your a/f ratio you might see readings a little higher, perhaps a point higher due to the load the dyno is having on your car. Chassis dynos can sometimes have a lighter laod on your car than when you drive it on the street.

ziobep

could higher numbers potentially be causing the revs at idle? or could it be dangerous for my motor?

soros151

at idle, the car is around 14.7-15.1AFRs stock.

ERIC-TC

A second option:

A replacement ECU can be bought from a junked car for like $100 on-line. Then you can sell the pigggy-back and get everything back to normal.