i recently purchased auterra's obdii software and interface and tried it on my car. this could be one of the few pluses of having a obdii car. it does all that it claims to do. one of the reasons i picked it is because it can help with your car diagnosis and the other is data logging. yes, i know that's what laptops are for... but anyway, the datalogging can be exported and converted to an excel file which is pretty neat if you want to graph the data. also, up to 5 sensors can be monitored at one time.

i thought this was pretty cool...i get to monitor my car's vitals and not have gauges galore in my car? all i had to do was hook it up my pda to the obdii diagnostic port and it syncs right up. stash it away, drive around, then download it to my computer.

i'm not exactly sure how accurate these measurements are but it seemed like it was... if lexus uses it for diagnostics, why can't i?

note, there are other pda softwares out there... i thought the auterra was the best overall for the money..but you'll have to research it for yourself.

below is a sample 0-100 run with rpm, mph and bank1 sensor 1 reading(o2 sensor reading?). i know there was some speculations about air to fuel ratios on our cars(how rich it was). this may clear it up?

by the way, the only engine mod on my car is the bfi...so almost stock. outside temp was about 76 f degreess(according to the car's digital temp reading) with high humidity..maf air temp was around 97-99 degrees...when i was crusing around, it was a consistent 20 degress above the outside temp. i'm guessing my heat shield and bfi has something with keeping the temps down though i have nothing to compare it against to verify.

that attached might help with voltage to a/f conversion if that's what the voltage is.


718 r/min 0 MPH 0.85 V
854 r/min 0 MPH 0.72 V
751 r/min 0 MPH 0.81 V
684 r/min 0 MPH 0.09 V
1400 r/min 0 MPH 0.035 V
1722 r/min 0 MPH 0.06 V
2050 r/min 1 MPH 0.78 V
2301 r/min 2 MPH 0.835 V
2518 r/min 11 MPH 0.86 V
2637 r/min 14 MPH 0.845 V
2648 r/min 16 MPH 0.88 V
2854 r/min 16 MPH 0.875 V
3172 r/min 19 MPH 0.87 V
3488 r/min 21 MPH 0.885 V
3811 r/min 23 MPH 0.865 V
4153 r/min 26 MPH 0.875 V
4475 r/min 29 MPH 0.905 V
4808 r/min 31 MPH 0.9 V
5158 r/min 33 MPH 0.92 V
5435 r/min 35 MPH 0.91 V
5725 r/min 38 MPH 0.91 V
5962 r/min 39 MPH 0.925 V
5365 r/min 41 MPH 0.92 V
4148 r/min 42 MPH 0.935 V
3769 r/min 44 MPH 0.935 V
3874 r/min 45 MPH 0.885 V
3998 r/min 47 MPH 0.895 V
4098 r/min 48 MPH 0.885 V
4223 r/min 50 MPH 0.89 V
4355 r/min 52 MPH 0.89 V
4470 r/min 53 MPH 0.895 V
4568 r/min 55 MPH 0.91 V
4664 r/min 56 MPH 0.895 V
4795 r/min 58 MPH 0.91 V
4915 r/min 59 MPH 0.89 V
5027 r/min 60 MPH 0.895 V
5137 r/min 62 MPH 0.905 V
5237 r/min 63 MPH 0.905 V
5319 r/min 65 MPH 0.905 V
5419 r/min 66 MPH 0.91 V
5539 r/min 67 MPH 0.91 V
5622 r/min 68 MPH 0.91 V
5716 r/min 70 MPH 0.9 V
5760 r/min 71 MPH 0.905 V
5850 r/min 72 MPH 0.91 V
5924 r/min 73 MPH 0.91 V
5971 r/min 73 MPH 0.91 V
6048 r/min 75 MPH 0.905 V
5435 r/min 76 MPH 0.9 V
4094 r/min 76 MPH 0.93 V
4195 r/min 76 MPH 0.895 V
4218 r/min 78 MPH 0.88 V
4271 r/min 78 MPH 0.88 V
4305 r/min 79 MPH 0.875 V
4345 r/min 80 MPH 0.875 V
4381 r/min 81 MPH 0.88 V
4422 r/min 81 MPH 0.88 V
4470 r/min 82 MPH 0.885 V
4502 r/min 83 MPH 0.885 V
4529 r/min 84 MPH 0.885 V
4556 r/min 84 MPH 0.895 V
4618 r/min 85 MPH 0.89 V
4658 r/min 86 MPH 0.88 V
4699 r/min 87 MPH 0.895 V
4723 r/min 88 MPH 0.895 V
4765 r/min 88 MPH 0.885 V
4814 r/min 89 MPH 0.89 V
4857 r/min 90 MPH 0.9 V
4896 r/min 91 MPH 0.9 V
4941 r/min 91 MPH 0.895 V
4967 r/min 92 MPH 0.9 V
4980 r/min 93 MPH 0.9 V
5054 r/min 94 MPH 0.895 V
5088 r/min 95 MPH 0.885 V
5116 r/min 96 MPH 0.895 V
5144 r/min 96 MPH 0.895 V
5201 r/min 97 MPH 0.9 V
5245 r/min 97 MPH 0.885 V
5237 r/min 98 MPH 0.89 V
5259 r/min 99 MPH 0.88 V
5054 r/min 99 MPH 0.86 V
3947 r/min 100 MPH 0.9 V
3846 r/min 101 MPH 0.855 V
3858 r/min 101 MPH 0.85 V
3890 r/min 101 MPH 0.855 V
3878 r/min 102 MPH 0.855 V
3742 r/min 101 MPH 0.745 V
3713 r/min 102 MPH 0.805 V
3705 r/min 101 MPH 0.55 V
3680 r/min 101 MPH 0.565 V
3613 r/min 101 MPH 0 V
3582 r/min 100 MPH 0 V
3644 r/min 100 MPH 0 V
3620 r/min 99 MPH 0.07 V

 

I guess from the readings you are running a little rich I guess that is safer. I'm installing a S-AFC in the next comming week. Lets see how it works out.

 

Cool toy! I've been thinking about getting one of those OBDII scanners to see once and for all how the OBDII interacts with an S-AFC.

From a book on OBDII that i read, it says there is indeed a "learning" mechanism in place. The way it works is by having a "long term" and "short term" fuel trim. When the short term trim needs to be adjusted for a set period of time, the long term trim is adjusted to compensate, and the process starts over. This happens all the time you drive your car. Both trim settings get reset to default when you use a scanner to reset them, or, as has been discussed, you disconnect power overnight.

This sounds to me like it would eventually "overide" any settings you make with the S-AFC. I'm very curious to know for sure!

 

from what I understand 14:7 or .5volts is the optimal air/fuel ratio for non-forced induction cars all across the rpm range.

This chart seems to be off
14:7 (optimal for N/A) should equal .5volts which is correct but should indicate optimal not superlean.
12.5:1 (optima for turbo) should equal .82volts not 1.0volts

I think that chart is incorrect.

can anyone verify?

 

Don't know about turbo cars, but on N/A:

"The ratio of air to fuel plays an important role in the efficiency of the combustion process. The ideal air/fuel ratio for optimum emissions, fuel economy, and good engine performance is around 14.7 pounds of air for every one pound of fuel. This “ideal air/fuel ratio” is referred to as stoichiometry, and is the target that the feedback fuel control system constantly shoots for. At air/fuel ratios richer than stoichiometry, fuel economy and emissions will suffer. At air/fuel ratios leaner than stoichiometry, power, driveability and emissions will suffer."

Go to Autoshop101 - Technical articles - Combustion chemistry for more details.