Fuel trim tuning

So how do you guys set up fuel trim data logs to match X and Y axis of the Speed Density Calculator? What PID's are you using? MAP is inferred in my car so I assume I should be plotting MAF vs RPM? Or is MAP calculated accurate enough?

I have MP monitoring setup so I can tell what MP I'm in relative to fuel trim event.

I'm I missing anything else?;)


Thanks Guys

Maf vs Peroid
STFT + LTFT
wb eq bank 1
wb eq bank 2
eq ratio commanded

mstang_man

I assume you're doing STFT + LTFT vs RPM so you can transfer/copy past into Speed Density Calculator? If so, how did you set up your X and Y axis?

The speed density calculator was broken so i never had a chance to use it, You'll notice the table is RPM vs. MAP vs. Load. The idea is, you hit a target RPM and MAP in steady state, and adjust the load to either the actual load if you're a MAF car, or adjust it based on fuel trims assuming your fuel model is correct if you're an SD car.
Lock your car in a given Mapped Point, or use the logged parameters to make sure you update the correct mapped point.

For example, if we're on a MAF Equipped Coyote, and we hit steady state, we may notice the load in our table is off from what we actually have measured via our installed MAP sensor and actual load. If we dial this in, we improve airflow anticipation and throttle control as the ECU can more accurately calculate airflows downstream of the MAF. By remaining in steady state, we aim to take out the effect any transient corrections based on the current model may have. Without a physical MAP sensor, this calibration is also just guess and check at that point. You cannot use the inferred MAP to try to correct it, as that's what you're trying to correct!

For SD cars, this is all you have to estimate cylinder airflow! You need this dialed in as it is the vehicles air model, which everything else based on load is based off of. Its the only way the engine knows how much air is actually entering the cylinders.

It sounds like my plan has holes then. I have my datalog set up showing mapped point weight% 0 through OP in the channels. I see it does indicate % as I log showing real time what MP is being used at the time either in whole or shared between MP's. I have absolute load vs RPM histograming STFT + LTFT. So as I play though the log, highlighted trim cells correlate to used MP points. I planned to go into speed density calculator and edit the respective cell vs MP to edit the Quadratic, slop, offset terms. The problem is no dyno. I though just driving around would collect enough data to trim out the fuel trims. I can see your point though that transient enrichment may taint my STFT + LTFT histogram data, or will it if I raise my count number to 10 or higher to increase the averaging of my collected data.

Any pids set up for fuel trims ?

You don't use fuel trims to correct speed density tables, at least on Coyotes. SD tables do affect fueling, but that isn't an accurate way to correct them, because many other things affect fueling.

Just setup a chart to match the SD calculator table, using calculated MAP and RPM for your axis values, and plot air load.

You can then duplicate that chart and filter by MP weight.