Explain Fuel Trims - Reset trims but set LTFT on start

[f.creek-ranch]

Hey there

Can anyone explain to me, when I reset fuel consumption, why my ltft are coming on at start.

Ive seen this, because I have a problem with P0300 and P0307 on a 392 and try to fix this.

Maybe its a leak in the intake or at the injectors, because I use adapter for LPG, but its been fine till now.

I reset the fuel consumption in the scanner but every start the ltft is already there before the 02?s are ready.

But one thing Ive been sure, there is a problem of a lean condition.

Maybe someone have an idea of the LTFT or the lean out.
Engine is stock but with lpg and the lean condition is in both operating modes.

cold.hpl

[Slidn]

Hey there

Can anyone explain to me, when I reset fuel consumption, why my ltft are coming on at start.

Ive seen this, because I have a problem with P0300 and P0307 on a 392 and try to fix this.

Maybe its a leak in the intake or at the injectors, because I use adapter for LPG, but its been fine till now.

I reset the fuel consumption in the scanner but every start the ltft is already there before the 02?s are ready.

But one thing Ive been sure, there is a problem of a lean condition.

Maybe someone have an idea of the LTFT or the lean out.
Engine is stock but with lpg and the lean condition is in both operating modes.

cold.hpl

Following.

[f.creek-ranch]

Problem is still there....

Why are the LTFTs already there and STFT must go to opposite to compensate this ?

What triggers the LTFT at startup when Fuel Trims are resettet ???

Cam settings ? Injector settings ?

AC_Clutch_nochauf.hpt

[veeefour]

You need to reset all adaptations. Fuel composition is for flex not for LTFT

[f.creek-ranch]

Consumption….

There is only reset for consumption and all adaptives in scanner.

I think I will try it with Alfa Obd or Appcar instead….

[veeefour]

Yeah whatever my phone autospell brings at the moment. You still using the wrong button. Use reset all adaptations LTFT must clear.

[f.creek-ranch]

I did a pcm write, clear adaptives and all LTFT are gone.

Whats the reason was, I dont know.

[TheMechanic]

I did a pcm write, clear adaptives and all LTFT are gone.

Whats the reason was, I dont know.

That is the purpose of the "Clear Adaptives". It resets anything that has a "learn" function back to a factory base of X. Then if all needed parameters are met it will begin a learn process of whatever it controls. Eg. Fuel trims, knock learn, timing, trans fill, shift time, etc. etc. When you perform a clear I like to drive it for about 10 miles or so at a light to medium throttle with small slow movements of the gas pedal.

[f.creek-ranch]

So far...so good.

Now Im trying to get better AFR at cold start, but the PCM wont let me do this.

By setting FA cold enrich 34210 higher, the LTFTs are kickin in before Ive start the motor.

I dont know the reason why.

123cold.hpl

Maybe its not necessary but I want to do this.


And my next point is, at 6:20 I get from P into D and all the LTFT are gone...

What table is used in this case or is it only the load ?

[f.creek-ranch]

New testings...

set fa cold enrichment higher - has no effect = 14,7

set burn fraction inverse higher / longer - when cl enabled the fuel trims goes negative = 14,7

set stoich to 0,0740 - no effect 14,7

set startup inj pw to 5,0 ms in the 0 rows till 64 counts - no change, but I got the feeling the light stumble after start is gone.

I think we got no tables in the gpec2, which gives us control over cold start fueling....
so closed loop enabled time is even useless.

What about Desired Airflow at startup 35020?

Will this affect the TB opening or fueling ???