[Supraman16]

Hey Guys,
I have a VPC/SAFC combo in my Supra. I had the set up tunned by UPRD and they tuned the VPC to -4 (2 clicks counterclockwise...it was running REALLY rich normally) on the gain and did the fine tuning via the SAFC. My question is in regards to the issue about to the ECU self-correcting due to running in closed-loop under 4000RPM when on partial throttle. Since the VPC is not set at 0 for the gain, will the ECU start to self correct after awhile? I'm thinking UPRD knows what they are doing considering they have been tuning Supras for awhile. but I just wanted to get you're guys take on this. Let me know what you guys think. Thanks... Darshana S...

 

[Andi]

It will absolutely re-adjust. Anything you do on the VPC's gain or idle knobs is worthless... and gets readjusted by the ECU, even on the WOT maps.

Do all your tuning at 4000RPM and above on an RPM based fuel computer such as the GCC, SRC, AFR, AFC, etc that regulates the simulated MAF signal going between the VPC and the ECU.

And do NOT reset the ECU between tuning runs or even right before tuning. What you should do is set the VPC knobs to zero... reset the ECU.. and drive it for a couple trips before dyno tuning so the ECU learns the VPC. Why? So you tune in the same learned environment that you normally drive in, so as to keep your tuning from being learned over and corrected by the ECU.

I think this is the heart of Brad Mayo's problem, for example... he tunes off the baseline just-resetted ECU tables, and then as soon as the car learns his VPC/etc his maps change... so he has to reset the ECU each time he wants to get back to his tuned state and perform well. If you tune on the already learned state instead of on a freshly reset ECU, your tuning shouldn't change while you drive as the ECU learns.

Andi

 

[Supraman16]

Thanks for the reply Andi. I had a feeling that would be the case considering everyone is bitching about the closed/open loop feature of our ECU's. Is there anyway to tune the low RPM fuel maps without having it screwed up by the ECU. I drive around mostly on the surface streets so I don't really get to see very many WOT runs unfortunately? ... Darshana S...

 

[Andi]

Why would you want to tune low RPM / partial throttle? The ECU aleady does a god job there w/ the o2..

Andi

 

[Supraman16]

Hey Andi,
I was just hoping to extract some more power out of the low end via leaning it out a little in the lower RPMs (since my car seemed to before run rich thoughout) without the ECU freaking out and reseting. But then again...I was thinking with the crappy 91 octane California gas it probably won't be such a great idea. So it's probably a good idea to keep it a little rich due to the crappy gas...Darshana S...