AFR What you should know

[Sandman]

Some of you have probably already seen this, but there is an interesting thread on NLOC about this. Something that Terry and other tuners obviously have to deal with and account for.

Part 1 (http://www.nloc.net/vbforum/1803288-post1.html)

Part 2 (http://www.nloc.net/vbforum/1810453-post12.html)

Full thread (http://www.nloc.net/vbforum/gen-2-lightnings/195396-afr-what-you-should-know-long.html#post1803288)

It does really beg the question of what defines a safe tune. With all the different mixes of fuel it can really throw your a\f off. How do you really program for this?

You'll also see in the thread the mention of an Ethanol Content Analyzer (http://www.zeitronix.com/Products/ECA/ECA.htm). It looks like it could be useful.

[Sandman]

Surprised there were no comments on this.

Has anybody had to retune to account for the ethanol content found in todays gas?

[PUMP]

I always ran 101 or higher race gas at the strip, so ethanol content was not an issue. Ethanol content does not usually pose a problem for daily street use since the ECM tries to hold 14.7 AFR in closed loop, and around here we get 93 octane pump gas. You do need to adjust tunes for ethanol if you do a street racing, or extended runs with high boost. Either of which can lead to detonantion, stabs in the wallet from tickets (or both of the above). The best protection is an AFR gauge and keeping your foot off of the pedal when running pump gas.

[Sandman]

Right, it's the WOT that the ethanol can throw off the A\F. But what is the fun in driving the truck daily if you have to keep your foot out of it?:burnout:

But even at the strip you're mixing the race fuel with pump gas, so there is still ethanol in the gas.

[PUMP]

Right, it's the WOT that the ethanol can throw off the A\F. But what is the fun in driving the truck daily if you have to keep your foot out of it?:burnout:

But even at the strip you're mixing the race fuel with pump gas, so there is still ethanol in the gas.Which is why you need a good AFR gauge and ability to data log.

[slick-svt]

Run it rich.....instead of 11.5 run it 10.5....:icon_question:

[Sandman]

so what is the key to a flat A\F? Assuming you have enough fuel, is it in the MAF?

[L8 APEX]

Air fuel is all in the tune and is controlled by editing the MAF transfer function. You can adjust the fuel added incrementally to the air that passes through the sensor.
10% Ethanol is not a concern for us, we are pig rich as it is. If it was an issue every vehicle in America would have to be retuned to run ethanol fuels. That is why they chose 10% ethanol for the pump. It doesn't require any changes.