I just hooked up the AEM Wideband and I already have a VAFC. I'm running 5.5 psi on a stock comptech kit. After the install I dynoed the car and at VTEC crossover the A/F spiked at 13.4 and then dropped back down to 12. With the VAFC I tried to move it around and got it to an even 12 from 4,000 going to 11ish at higher rpms.

My questions:

What is the best A/F ratios for idle?

Target A/F at steady highway driving?

Should the the loop be Map - ESM - VAFC - ECU? Or otherwise?



I also remember there was a thread all about how to use the VAFC, can't find it in the search but I remember a year or so ago I was reading it.


Any help is appretiated, feel free to post other questions about this topic.

 

this is some good questions... about target A/F ratios.... should be added to the FAQ when answered...



D.

 

Highway A/F you want around 14.7ish

Idle, I'll have to look at mine when I get home.

 

Nice. Thats exactly what I'm at.

Another question, at what throttle percentage should the AF start dropping to the 12 range. Is it only at WOT that it should be rich or should partial throttle be down there as well?

 

Here's a dyno plot with AFR plotted against RPM (ignore the 5.5k rpm) I targetted just over 12 across the range. On the stock ECU/ESM set up they do seem to go lean just just before vtec.

 

Spikes exactly to 13.4. How many pound you running?

 

I do quite a bit of tuning so here's my .02

Idle/Cruising (30kpa to 75kpa) 14.7 to 15.2 a/f
Mid Throttle (75kpa to 100kpa) 13.5 a/f
WOT NA (approx. 100kpa) 12.5 to 13.0
WOT Boost (110kpa to 300kpa) 10.5 to 12.5 a/f depending on Gas, Boost Levels, and how conservative you would like you vehicle to be.


This is a WRX I recently tuned. It has a Boost curve and Air/Fuel Ratio Curve.



Hope this helps.

Corey

 

Does your Car have a High Output fuel Pump i.e. Walboro 255hp?

If not, that will probably get reid of that spike. Your Fuel Line is running out of fuel for a quick moment after vtec kicks in.

Corey

 

AEM EMS isnt tuned off of TPS, its tuned off of Engine Load. Basically, once I get 1psi of boost, the A/F drops down to the 12s then 10s.

 

When I had EMS on my last setup I had that boost comp map like I think you have but on the VAFC there is only 2 settings. Just don't have an extra thousand to drop on EMS.



Would it be better to set "hi mode" to start lower like 40% throttle or higher like 60%?