How lean part throttle is acceptable?

[Force Fed Mopar]

Tune it where it responds to throttle changes the best and it'll be efficient.

[dieselgeek]

FuelTech makes wideband sensor kits cheap... and are based in Brazil. No excuse not to run one, a narrow band isnt helping you much at all.

We ran 8 of the same sensor kits at EMC this year on Bradley Nagel's 2nd place hemi, also we used the FT500 ECU. Brazilian and an excellent product!

Let me know if you need a link.

[BrazilianZ28Camaro]

FuelTech makes wideband sensor kits cheap... and are based in Brazil. No excuse not to run one, a narrow band isnt helping you much at all.

We ran 8 of the same sensor kits at EMC this year on Bradley Nagel's 2nd place hemi, also we used the FT500 ECU. Brazilian and an excellent product!

Let me know if you need a link.

Yeah, I do know the guys, they are really concerned with their product quality. They have good results with their products too. I may consider buing one kit but do you know, I'm a old school guy...

[Walter R. Malik]

Exhaust temperatures are much more important than fuel ratios at part throttle, low power, cruising RPM.

As far as air/fuel ratios ... I have seen 15/1 or a bit more work well until more throttle opening happens. Higher than 12/1 compression will need a bit less.

[BrazilianZ28Camaro]

Exhaust temperatures are much more important than fuel ratios at part throttle, low power, cruising RPM.

As far as air/fuel ratios ... I have seen 15/1 or a bit more work well until more throttle opening happens. Higher than 12/1 compression will need a bit less.

Good point Walter, the engine runs cool, cooler than I'd like, even with a T-stat.

Do you know to what voltage that 15:1 AFR correlates ? This way I can have an idea where my NB gauge should read at part throtle.

[Truckedup]

Leaner part throttle mixtures will generally require more spark advance to maintain decent throttle response

[F-BIRD'88]

Here is a graph of the NB o2 sensor voltage output.
Realize and remember that the voltage is effected by the exhaust temp at that moment.
And the O2 content in the exhaust is a average of all cylinders and is effected by exhaust reversion, especially at low rpm and high cam overlap.
The gauge is very accurate at/near the stoichiometric ratio zone.
But this gives you an idea. As long as you understand what it does and does not show you.

Watch your plugs too.

[BrazilianZ28Camaro]

Here is a graph of the NB o2 sensor voltage output.
Realize and remember that the voltage is effected by the exhaust temp at that moment.
And the O2 content in the exhaust is a average of all cylinders and is effected by exhaust reversion, especially at low rpm and high cam overlap.
The gauge is very accurate at/near the stoichiometric ratio zone.
But this gives you an idea. As long as you understand what it does and does not show you.

Watch your plugs too.

Thats what I was looking for and I agree totally with you wrote above.

Yes the spark plugs have aways the final verdict, at least in my book. I may try 1-2 degrees more advance too.


Thanks F-Bird!

[BrazilianZ28Camaro]

And the above chart would explain the slight hesitation I'm seeing, the part throtle AFR probably was around 17.5:1 !!

As soon as stop raining on my day offs I'll re-test the car with smaller IABs and report back.

Thanks all for replies.