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3rd & 4th Gear AFR

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Yesterday i went for road tuning

i did 3rd gear pull and i data log it.

so i started to tune my fuel table to suit my target AFR at wot as my mine purpose to tune wot only.

after i did few changing i went for a ride and i found out at 4th gear the car more richer than my target AFR but 3rd still remain the same as i did.

What is the best way to make the rpm read the same afr for 3rd & 4th gear?

im using Map Load as the Load input of the fuel table.

using a piggyback ecu for now as im a beginner at tuning

Are you seeing the same cells on both the 3rd and 4th gear runs?

You should be. On your WOT runs do you use the last row of load cells or this there a row above that the ECU does not go into?

I'm guessing in 4th gear your accessing higher load points on your fuel table, as opposed to in the lower RPM wot region in 3rd. depending on your turbo size you may not be accessing those high load cells in the lower RPM region as you are in forth. just my thoughts.

Thats possible if gear referenced boost is enabled and tuned, I find though that I achieve the same boost in 3rd that I do in 4th, its just the transition to boost is slightly different.

Yes im using the last 2 cells which is 95 , 100 KPA as my data long says. during wot at 3rd gear all my load around 96 kpa .

i compare my data long for 2nd gear & 3rd gear i found that the run at the same cell but im not sure about 4th gear as i can't get a data log for it.coz it's hard to find a long free road without cops ;D

i found out that it was richer at 4th gear while i was driving normally by watching my AFR gauge.

yesterday i change my load input from MAP to TPS and it works fine with 3rd gear and 4th gear just a slight diff btw them.

but i feel working with MAP input is better than tps.

Note : it's a naturally aspirated not a boosted engine .

What are you using for logging?

You were talking about WOT but say AFR is different under normal driving, tuning in 3rd gear at WOT will/should see the same values as if you were at WOT in 4th.

Is your issue at cruise as you just stated, "i found out that it was richer at 4th gear while i was driving normally by watching my AFR gauge".

im using aemlog .

sorry maybe i said it in a wrong way.

yes im at wot in 4th gear. but i didnot go until red line coz of the short road.but i saw the afr drop to richer area as soon as i hit the cells which i already made it to work at my afr target. thats was around 5500 rpm.

i also did 2nd gear data log and i tune base on the 2nd gear log after that i get my afr right where i need it.

then i went for 3rd gear wot from 3000 rpm to red line

i also found it more richer, it almost hit 11.8 at some area and my target was 13.0

You will see the AFR fluctuate slightly based on the rate of acceleration through the fuel table. This is due to the volume of the fuel film on the port wall and how this fuel film changes with rpm rate of change. If your ECU doesn't correctly model the fuel film (which most don't), this will show up a lean mixture in the lower gears where rpm ROC is higher, and a richer mixture in higher gears where the rpm ROC is lower.

The more important part in your WOT tuning is to ensure that the AFR is suitable under heavy load. This is why I suggest performing your WOT tuning in a higher gear such as 4th. In the lower gears (1st/2nd) the rpm acceleration rate is much higher, and while the AFR may end up a little leaner, there's less load on the engine and hence it's unlikely to present an issue. On higher power applications you may want to utilise gear trims to get the AFR where you want it.

Thanks Andre for your reply and thx for Pete as well.

That's explain alot.