What is an acceptable AFR Air to fuel ratio
 

I own a cobb access port and it been reading my afr as 14.5 - 15.5 at idle generally. Is this rather high or am i a little paranoid. Im running mazda maniacs base tune for my year. Help Please?

Yes, you are being paranoid.

Thank you charles!

Whats your AFR at wot?

+1

Log a pull to redline on your AP, upload the data, plot it in excel and post an image of the graph.

My log shows a AFR at WOT as 11.7.

That's alright? Still totally stock.

Thanks.

sounds fine

Thats actually a nice relatively lean mixture for being stock.

I've seen stock Mazda maps produce 10's at WOT.

Afr 11.7
 

Just to be clear... that is with MM base map, on totally stock engine... no mid pipe....yet ;-)

I did not measure that with the Mazda stock ecu... not sure how to do that? as I had to load MM base tune map to get the the Access Port to log anything.

:-)

Log it for us!

You datalog AFR and other stuff - You need to practice data logging anyway. :)

Plug AP into your computer

Transfer the datalog

Open in excel - if you don't have excel then download Java office suite for free

Create a chart

alt-Print screen

Paste in paint

Save as jpg

Post picture

Will do!!! not at the right PC at the moment.. but will fer sure... :-)

Picture of log
 

I could not figure out how to chart it properly... I would get a nice line showing the RMP, but other values would be burried at the bottom and would not show any usable data.

i usually get low 12's at WOT

that's 11.1 not 11.7

This is a pretty big topic and not one that has a definitive answer. There is not really an "ideal" air/fuel ratio because a proper ratio will vary based on RPM and calculated load. What is considered proper is going to depend on your fuel octane, ignition timing and current operating conditions of the motor.

The MazdaManiac base calibration does not make any changes to the stock fuel tables so what you are seeing is the stock fuel settings for the RX8. MazdaManiac is well aware of what air/fuel rations are optimal for the performance of the vehicle based on your modifications so you have nothing to worry about.

Loaded first map...
 

I took the base settings and increased the RPM limiter and adjusted the idle up about 30 rpm to see if it makes any differance.

RMP's are now hitting 8500 vs the 8000 limit as stock. Idle did not seem to change. At least I could not notice.

Gonna play a bit more tomorrow after I get my midpipe on... I got the stock pipe out this evening without any issues. Bolts looked like new....no rust!!! Crazy for an 04.

Cat also appeared to be in good shape, maybe it was recently replaced? Car is new to me only 3 months ago... so who knows. The screen in the cat had very little deposits on it... Will take a picture later.

Will log more tomorrow... see where I land. Go for a good cruise, hit different RPM's and loads.

:-)

Did another drive and logged...
 

Hey gang...

Did another drive on the highway yesterday....

Attached are some screen shots:

Fisrt pick is a 2nd gear pull WOT

Second is a 3rd gear pull at WOT

Mods done:

Agency Power twin res midpipe, K&N airfilter. 2004, 4 speed AT tranny.

This is the first run of a stock map just loaded with max RPM's increased to 9000, Thats it.

I am thinking that I should see a higher mass airflow? maybe not? Stock airbox used.
Also... is 11.17 a good AFR for that type of engin operation? Should I not want that a bit leaner?

I will keep this map on for a few more drive cycles see if anything changes...

Any coments???

Awesome thread, thanks for sharing!