What air fuel ratio at full throttle ?

[dixie]

This is a question for you guys with a Dashhawk or aeroforce interceptor,how much air fuel ratio do you have at full throttle,mine shows around 12.5 and 13.5 which I think is a litlle to lean , I think it should be around 11.5 and 12.5.
My car doesn't have a flash..
Thanks...

[shabby]

At low rpm it goes from 14.0 and eventually settles at 12.7 past 5000rpm. Since this is a direct injected engine its not lean at all, this is the afr the ecm wants.

[BlueSkyRL]

Actually you will here/read different ratios from people, BUT the laws of physics says 14.7:1 is the right ratio. Why do you and others see different readings??? Because the point of explosion is at 14.7:1 and the rest of the "free" chamber figures into the reading everyone sees. Sometimes 11 - 12:1 is what some see and think thats right, but that's not really true. The best way is to watch the temperature, fuel ratio, o2 sensors, tq and hp increase/decrease, knocking....all to determine the right ratio.

[BlueSkyRL]

Originally Posted by shabby

At low rpm it goes from 14.0 and eventually settles at 12.7 past 5000rpm. Since this is a direct injected engine its not lean at all, this is the afr the ecm wants.

Yep...this partly the story behind it all

[dixie]

Ok thanks guys, I'm also driving a porsche 996TT and at full throttle air fuel should be around 11.5 and 12.5.Seems to be different for the sky redline.

[Bogie]

The VVT valve overlap for the Ecotec can push uncombusted fresh air through the cylinder. Without calibration, the downstream sensors can read lean when the actual combusted mix is rich. In the stock configuration, this is accounted for by using a wideband 02 sensor and calibrating the reading in the ECM (since it will be aware of the valve overlap).

[dixie]

So if I understand you correctly when I see 13.5 on my dashhawk it could be a wrong reading and it could be for example 12.5 ?
I don't know for a redline but 13.5 for a porsche turbo at full throttle will destroy the motor...
Just trying to learn about the redline because I will soon have a flash and I want the A/F to be perfect.

[Bogie]

Originally Posted by dixie

So if I understand you correctly when I see 13.5 on my dashhawk it could be a wrong reading and it could be for example 12.5 ?
I don't know for a redline but 13.5 for a porsche turbo at full throttle will destroy the motor...
Just trying to learn about the redline because I will soon have a flash and I want the A/F to be perfect.

It depends on if the information the dashhawk is pulling has been adjusted by the ECM or not. And if so, by how much and with what error margin. I don't know the answer.

Maybe one of the main engine tuner folks can provide insight since they reflash the ECM and would need to be knowledgeable about such things.

[shabby]

Originally Posted by dixie

So if I understand you correctly when I see 13.5 on my dashhawk it could be a wrong reading and it could be for example 12.5 ?
I don't know for a redline but 13.5 for a porsche turbo at full throttle will destroy the motor...
Just trying to learn about the redline because I will soon have a flash and I want the A/F to be perfect.

Here is the afr the ecm commands at certain rpm, if you're seeing 13.5 your probably at around 4500 rpm. Log one of your wide open throttle runs from 2000 rpm to redline and you'll see this on your dashhaw.

14.0 afr @ 1200-4000 rpm
13.6 afr @ 4520 rpm
12.9 afr @ 5000 rpm
12.8 afr @ 5320 rpm

[dixie]

Ok thanks a lot guys,I thought I was running lean but now I know my A/F are normal for a redline.