Throttle is different when first started (cold) then after warmed up.

[loganlewis]

I recently did calc.vet with the help of weathermanshawn and Joecar, it really helped the truck out. I notice the truck still feels stronger when it's cold as to after it's warmed up. I mean if I barely tap tge gas it will spin. Once it's warmed up I really have to try to get it to. The truck just feels stronger period when it's cold. Why is this? And is there a way to make it that strong the whole time?

[Taz]

Engines will always make a little more power when cold. For best performance drag racers ideally like the engine oil hot, the coolant warm, and the intake air cold. That said, it sounds like the magnitude of difference in the performance of your vehicle (based on temperature) is outside of the norm.

With a cold engine the PCM may be commanding an A/F ratio that is richer than stoich. The engine is also more knock tolerant / resistant when cold - and may be able to tolerate more spark advance than when at operating temperature. Also, depending on how the vehicle is being driven - the PCM may be commanding PE if you are below the PE temperature threshold.

Check the value of B3612 (low temp PE bypass) in your tune. Also check B4205 (closed loop temp enable) - it may be the case that the phenomena you describe is occurring when the engine is in open loop, and the O2 are not yet trimming the commanded fuel - especially if B4206 is set to "Disable".

Then from a cold start log the following while you drive, and as the engine warms up to operating temperature:

wide band O2 output (actual EQ / Lambda / AFR)
EQIVRATIO
ECT
IAT
KR
SPARKADV
ASPARK
Hopefully this may point you in the right direction ...


Regards,
Taz

[loganlewis]

Its definitely when the motor is in open loop. It accelerates so much easier and taking off feels stronger. Once it's warmed up....acts like a dog

[WeathermanShawn]

You might want to Disable B0701 CAT Protection. Its adding way too much fuel.

Also, consider increasing B4307 Desired Airflow in your higher ECTS. A lack of Airflow can make the throttle 'feel' dead.

[Taz]

Good point WeathermanShawn on the Desired Airflow (B4307) ... I hadn't thought of that. If you are running an automatic transmission, B4307 mods can be a bit of a balancing act. I find if I set these too high, the vehicle will feel like the engine is "pushing" forward, as you apply the brakes when approaching a stop sign / red light. This effect seems to be more pronounced when the engine is cold - as the Desired Airflow when the engine is cold is of a much greater magnitude than when at operating temperature.


Regards,
Taz

[loganlewis]

How much will I know to increase b4307 by? I am looking at the tune now at 154* ect it's .926 then from 176-241* it's set at .701. Seems like quite a drop to me... Correct me if I'm wrong

[WeathermanShawn]

Even though B4307 is listed under 'Idle', Desired Airflow is used at every point in operating the engine. First, you need to start using metric (g/s) or none of this will make sense.

Check out No. 2 under this Tutorial..it takes all the guessing out of it: http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks