STFT only?

[Rob]

Any problems running just STFT and not LTFT? I had been doing VE and then MAF tuning with STFT. Got that pretty nice, between -2 and 2. I then turned on LTFT. Nothing is as it was with just running STFT.

So can I just leave the LTFT off? I can't see why not but I figured I'd ask for opinions.

Thanks.

[Russ K]

I always keep the LTFT's enabled. The LTFT is the "learned" fuel trim, this allows the STFT's to just fine tune the closed loop AFR.

In order to use all of the available fuel trim cells (LTFT), the LTFT map & rpm boundaries need to be set up to match the camshaft & idle speed. The stock LTFT map boundary is 37,57 & 77 KPA. The stock LTFT RPM boundary is 900,1400 & 2200 RPM. So if your new camshaft idles at 50 KPA & 950 RPM, you will only be using 9 of the 16 fuel trim cells.

Setting the map boundary table to be 55, 65 & 80, and the rpm boundary table to 1000, 1500 & 2300 would enable all 16 fuel trim cells.

Russ Kemp

[Rob]

I'll go ahead and change the boundary's and see what happens.

Thanks, Russ.

[5_Liter_Eater]

Lately I have started to leave LTFTs disabled. The STFTs are non-volatile meaning that they are not cleared with each ignition cycle so I don't see the need to take an average of them. If a particular cell is +5 STFT then it will stay there until it needs to change. The benefit is that things are simpler and more importantly, STFTs do not affect PE. So I could have a +10 STFT and it would not affect my PE fueling like a +10 LTFT would.

Changing the boundries is a good idea.