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Practical Reflash Tuning

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Discussion and questions related to the course Practical Reflash Tuning

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Hi Andre,

we are using HP Tuners and struggling with a few things:

1. By clicking the disable button to LTFT and STFT is that sufficient or do we need to change values in order to disable them?

2. Should we reset LTFT before adjusting VE Map? or as this is disabled it doesn't matter?

3. When finished with VE Map is it better for Speed Density to not have LTFT enabled

4. Is there anyway of adding 1 bar speed density patch to an ecu that has not got the option in OS

5. We have had a Holden VX LS1 arrive that was mafless tuned and standard. We have now changed the intake, exhaust, cammed the motor and need to retune the car. Are you able to supply in dot format? the procedure that we need to undertake?

ie Turn off Fuel trims

set PE table to x figure

set up idle?

steady state tune by filling in AFR error graph and apply to VE

power run to confirm AFR

Timing by applying 2 degrees to entire map and run? watch for knock and adjust?

I "think" i have a handle on the process but just want to confirm before we start this on a daily basis

Hi Brock, I'll deal with your questions one by one.

1. I personally disable the trims as described in the course, however provided your trims are all showing zero in the scanner, then you know they are not influencing your fuelling.

2. As above, you want to ensure the LTFT (and STFT) are showing zero. If not then resetting the trim is an important step.

3. Whether or not you chose to leave the LTFT enabled is personal choice. I tend to disable it but I know plenty of tuners leave it enabled. My thoughts are that if we've done our job correctly then the ECU should be much less reliant on the fuel trims to maintain a stable AFR and this way the LTFT won't affect the open loop fuel delivery.

4. If your PCM has not got the 1 bar SD option then you can disable the MAF to force the PCM into SD only mode and then perform your tuning in the virtual VE tables.

5. The procedure for tuning your cammed VX is really no different to any other combination and I'd recommend simply following the 6 step process. In particular you'll need to make some changes to the VE table based on the cam spec. You'll find a decent cam will reduce VE in the idle region up to perhaps 2500-3000 rpm. Above this point you'll need to increase the VE. You will also need to set the PE table to your desired open loop lambda targets so you can correctly tune the VE table. The biggest focus with a cammed LS is the idle. You'll need to increase the idle target (dependent on the cam size/overlap), and then you'll need to increase your base running airflow table to achieve a stable idle with no dipping/stalling.

Initially I'd start by setting the warm idle speed to perhaps 850 rpm and add 15% to the entire base running airflow table. Once you have the tune a little more dialled in you can set up a histogram and log the airflow values so that you can correctly fill in the base running airflow tables.

Once you get to performing ramp runs you can add timing as you've mentioned above while monitoring for knock. Let us know if you have further questions.

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