AFR Datalog Plots?

[Black_Sunshine]

I'm new to using a datalogger for carb tuning and would like to see what is considered an acceptable/good/proper, even bad AFR vs RPM vs MAP plot for a wide open throttle run (1/4 mile pass), cruise on idle circuit, and cruise beyond idle circuit.

I have an innovative wideband setup and have added MAP and RPM via their SSI Four+ logger.

Please post up examples. Thanks!

[rgalajda]

What fuel, carb, and engine?

[rgalajda]

For typical non oxygenated 14.6 to 14.8:1 stoichiometric fuel , naturally aspirated engine.

Rich at idle 12.5 to 14:1 , lean at cruise 14.5 to 16:1 ,( leanest mixture which the engine will tolerate without missing or surging in level road cruise and moderate to intermediate acceleration). Leaner or leanest at part throttle acceleration until the power valve opens and rich at WOT , 12.5 to 13.4:1 AFR.

Idle AFR will be dependant on camshaft specs. More duration equals less vacuum requires richer idle.

Minimum fuel consumption at idle usually requires the vacuum advance adding about 20 degrees more timing . ( this was done away with in light of emissions )

Lean cruise of say 60 mph will be dependant on vacuum advance adding timing to as far advanced as 45 to 55 degrees.
A typical performance Holley carb should be able to achieve 15:1 AFR at cruise.
A Quadrajet or Cater carb can acheive 16:1 AFR at cruise.

[rebelrouser]

I don't have any plots to post but rgalajda comments are spot on. One thing to remember is that when you get your data plotted, don't get excited by spikes. I believe the monitor you are using has the ability to smooth the graph traces. I think you will make better tuning decisions by smoothing your plots. Also remember any exhaust leaks will give false readings, and no engine fires every cylinder every time. One of the reasons you will get spikes in the data.

[In-Tech]

Huge lean spikes are misfires.

I don't have any logs to post, good on you for looking at this