Gernby

For some reason, it seems that most people set the Lo/Hi Throttle settings at 10%/50%, and I am curious what the reasoning is behind this. Many people claim that our ECU can learn to compensate for the V-AFC corrections over time, reducing its benefit. It seems to me that there are a couple ways to reduce this. One thing would be to set all the partial throttle corrections to zero, and the other is to raise the Lo/Hi throttle settings.

I have found that I am never driving at a throttle position of less than 10%, so the V-AFC is always interpolating some correction factor. Quite often I am over 50%, and the V-AFC is applying the full correction factor. I have also noticed that my car seems to get weaker and weaker, until I reset the ECU, and it is strong again.

Would it not be better to set the Low throttle setting to a high value (80%), so normal driving will cause no correction? A High throttle setting a bit higher (85%) would cause the corrections to only be applied when the driver is really motivated, and there would be a small interpolation between. It seems that this would play a big role in preventing the ECU from learning how to uncorrect the correction.

Hams2000

Just pull your ECU fuse so it resets everytime you key off, that way the ECU cant trim the fuel maps to "tune" out the VAFC's settings. Also keep in mind that the ECU only trims the partial throttle maps, not the WOT map. So... if you leave the fuse in the narrow throttle settings on the VAFC will become useless with time.

I personally used the narrow throttle maps on the VAFC to lean out my car at cruise to attain better gas mileage. I had my Lo/Hi on %50/%60 because any throttle angle BELOW %50 will run the Narrow Throttle map, where I have the car running lean for mileage. Anything in between the %50 and %60 will split the difference in a sense, and then anything above %60 will run the Wide throttle map. If you want a clean break with no difference in the settings, then run something like %50/%51. If you have the Lo set on %10, you'll almost NEVER use the narrow throttle map function of the VAFC... Let's face it, how often do you drive around at %10 throttle, even at cruise? Perhaps you could watch your throttle angle at cruise, and then make your decision from there you know?

Chris

Gernby

I do pull the fuse (and leave it out) some, but I hate how crappy the idle is. If I just reset the ECU every few days, it runs AWESOME.

Hams2000

Yeah, it does idle crappy doesnt it? Actually you could lean out your idle trim on the VAFC and get a good idle though.

Chris

Gernby

Thanks for that link. I hadn't seen that thread before.

Hams2000

The ECU will trim it's fuel maps in closed loop mode, but it's not instant and if you reset your ECU, as in take out the fuse, you can take advantage of the narrow throttle settings on the VAFC. If you leave the fuse in place and, it becomes useless to tune that part of the map.

I also agree that the VAFC's shortcoming is the lack of ignition control which led me to my quest on my EMS. I made the greatest gains by tuning my ignition curve and running my car in the 13's A/F-wise. The stock ignition curve is pretty conservative and of course fuel economy plays a lot in that since the lack of fuel, or richness tends not to support an agressive ignition curve.

You can really see the difference on the VAFC when you lower the Vtec engagement point. You engage Vtec lower and change fuel, but the car's ignition curve is still thinking it's not in Vtec.... Hmm. The EMS was worth the money IMO.

Chris

Gernby

I thought about the AEM EMS, but I decided that I would get more bang from my limited budget by getting the V-AFC. If I can justify it, I would like to go with 4.77 gears. I figure the gears and V-AFC together would cost less than the AEM EMS, but have better results.

Hams2000

Do you think you would have driveability issues with the 4.77's? Gears have been next on my list for mods, but I have been leaning towards the 4.44's. I assume your considering the 4.77's for auto-x?

I just want to get my car back so I can put her in the garage and never let her out again! Ooopss.... that's another story....

Chris

Gernby

I would love to do the 4.77's, but that would make 6th gear about like 5th with the stock gears. I don't do much driving on the highway, but when I do, I often drive in 5th just to see if it would bug me to run such high RPMs all the time. I am sure I would get used to it, but driving at 5000 RPMs at 75 MPH is annoying.

I really wish someone would release a taller 6th gear set that would put the Highway RPMs back down to what they are normally. If I went with the 4.44s, I am afraid that I would regret not going all the way to 4.77.

Hams2000

That's a good point. I never drive my baby on the highway either. I only use it for "convertible" weather and round town drives... The problem is that many times I do like to open it up and hit some major top speed, so I think I would regret the 4.77's

Chris