IAT % Variance

[Viper Specialty]

Trust me guys, the VEC-2/3 operates in open AND closed loop, the only question is, if it is capable of doing anything in closed loop. Fuel wise, it is not, the PCM will adapt around it. for IAT and timing, it most certainly is, those are not an adaptable parameter in the PCM.

The VEC's have no idea whether the PCM is in open or closed loop.

 

[ViperBing]

Thanks for this info! I will give it a try and adjust from your parameters.

I now have one card which consistently gives me the AFR I want from 50F-95F. The trick is setting temp parameters and then balancing out the fuel add/subtract. It took a little monkeying around to find the balance point bewtween fuel add/subtract and IAT % correction........and may never be perfect, but it's working just fine right now. I'll run some 30F degree logs when I can in the next few weeks

My settings: +16.1 / -11% and temp parameters of 35F to 126.1F. Here is a screen shot of my settings.

Steve

 

[Steve 00RT/10]

For those who have been following this thread. I finally got a chance to get some cold runs in today at 30F. By the time I got to the closed course and did my 1st log, the IAT reading showed 39F for starters. This will be about the coldest we see on a nice fall or spring day. The results are interesting. I made 5 or 6 runs altogether with a couple different settings. Although I was quite happy with the results from my earlier post....at 50 degrees, I was starting to get a tad rich and mentioned that to a couple interested guys. At 40 last week...it was a tad richer --even though those settings in hot temps produced about 11.6-11.8 AFR. I did not want to chance any adjustments until I was able to run a 30 degree log. Sure enough...it was a little richer yet. Certainly not unacceptable, but a tad heavy (11.1 --11.4 on average). I played a little this morning with fuel and IAT. I am now at +13.1 and -11 with the same temp offsets as above. I also removed slight fuel in a couple places.

What seems to be happening as one tries to dial in the entire range with one card is that the non linear portion of the equation is coming into play a little. Because of that, I'm not sure it can ever be perfect. .But it sure is better than running 3 cards which are committed to a certain set of parameters. This sliding scale is much better. In reality, running 11.1 or 2 up to 11.8 across the spectrum of temperatures should be good enough. That is covering a range of ambient outside temp from 30-95F and IAT sensor temp from 39-115F. For 99% of all who do this, it's probably plenty close enough. I just wanted to tweak it a little more.

Adding the roller rockers into the mix last spring and the upgraded VEC 2 was kind of like starting over. I'm going to check this one more time cold and then call it good. I will have to check the upper end again next year to make sure I didn't upset the balance dialing in the cold a little better.

I can tell you this.....even at a 11.3 or so AFR......at 30F, my 5 pounder runs GREAT! Per my first logs this AM,

3rd gear................2792 RPM to 5261(48 to 90.70 MPH) in 3.45 seconds. This is steady state and hitting it at 2250 RPM.
2nd gear................3574 RPM to5486 (45-69 MPH) in 1.7 seconds ( held at 45 before hitting it--wheel spin occurred with my new PS2s)
4th gear..................4563 RPM to 5380 (102-120MPH in 2.05 seconds. (this was done with some momentum from 3rd gear upshift--same shift lag as below).
Similarly in 2nd gear accelerating through 1st and shifting (1.5 second lag between gears per the log) 52.09 MPH to 67.69 in 1.05 seconds. These are definitely smile inducing times

I should emphasize........this my particular car. This may not work for all, but I hope it's helpful for those playing around with this function. Anybody else with other findings...fell free to tutor the rest of us. Like HP, too much knowledge is never enough.

I would also be curious to see how my car stacks up against other 5 pounders...self or dyno tuned.....as relates to similar performance parameters as I listed above. I don't really know if these are good numbers or not. Sure seems good to me.

Steve

 

[EllowViper]

Good Job Steve! The tune you sent me continues to be working great....actually even better in the cooler morning temps. My Innovate WB has not arrived yet so I can't tell you how your tune is actually performing A/F wise in my 5 lb creampuff. Excellent point about sharing tuning tricks and other findings. I'll be sure to send you my logs once that darned Innovate arrives!!