OBDII readers, Air Fuel readings accurate?
#1
OBDII readers, Air Fuel readings accurate?
I've been out of the tuning biz for a while and all the usual wideband players are still around (and all with the same issues ironically). Anyway...I had been debating acquiring a wideband that I could datalog.
I have an IPL with the Nismo R-Tune intake and a set of FI HFC's arriving some time in the next month but hopefully sooner.
On a whim today, I added an 02 gauge to my OBD Fusion program (iPhone) which monitors all the of the car's sensors via a Bluetooth dongle that plugs into the OBDII port. I can select a number of 02 gauges and one is "Actual" O2 readings.
Now it's always been my understanding the OEM 02 sensors are not true widebands and aren't accurate outside of a certain range.
I'm getting very specific numbers that coincide with what should be happening whether I'm running closed loop or open loop. WOT is producing numbers in the 11's and I did see it hit high 10's. I haven't logged anything so I'm just glancing at it while accelerating.
Anyway, I'm sure it's interpreting the voltage and not sure if our 02's are linear or non-linear.
I have to learn how to log and save the data files, haven't figured that out yet.
If anyone has actual knowledge about our 02 sensors and their ability to read accurately outside of stoich, let me know! All of the cars I tuned were pre-OBD II and we all used aftermarket widebands.
Thanks in advance!
I have an IPL with the Nismo R-Tune intake and a set of FI HFC's arriving some time in the next month but hopefully sooner.
On a whim today, I added an 02 gauge to my OBD Fusion program (iPhone) which monitors all the of the car's sensors via a Bluetooth dongle that plugs into the OBDII port. I can select a number of 02 gauges and one is "Actual" O2 readings.
Now it's always been my understanding the OEM 02 sensors are not true widebands and aren't accurate outside of a certain range.
I'm getting very specific numbers that coincide with what should be happening whether I'm running closed loop or open loop. WOT is producing numbers in the 11's and I did see it hit high 10's. I haven't logged anything so I'm just glancing at it while accelerating.
Anyway, I'm sure it's interpreting the voltage and not sure if our 02's are linear or non-linear.
I have to learn how to log and save the data files, haven't figured that out yet.
If anyone has actual knowledge about our 02 sensors and their ability to read accurately outside of stoich, let me know! All of the cars I tuned were pre-OBD II and we all used aftermarket widebands.
Thanks in advance!
#2
Our engines use an "Air/Fuel Ratio" sensor (aka wide-band) as the pre-cat sensor. It can read air/fuel ratios from 10:1 to 30:1. Our post-cat sensor is the old style narrow band o2 sensor.
From FSM, EC-236:
I suspect if is accurate enough for the car to pass EPA/CARB emission, it is just as accurate as any aftermarket wide band. Article on wide band accuracy: http://tunertools.com/articles/FordMuscle.pdf
The Fusion App is very good and you can log data and send the file (CSV) to other devices for further analysis. I use it often.
From FSM, EC-236:
I suspect if is accurate enough for the car to pass EPA/CARB emission, it is just as accurate as any aftermarket wide band. Article on wide band accuracy: http://tunertools.com/articles/FordMuscle.pdf
The Fusion App is very good and you can log data and send the file (CSV) to other devices for further analysis. I use it often.
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Ape Factory (07-05-2016)
#3
Thanks for the article. I used the Innovative LM-1 back in the day. Really disappointing to hear the Zeitronics unit did so poorly, they have a cool gauge option which is essentially just a thin LCD that you can house yourself. I was looking hard at that one.
I was not aware the precat sensors were true widebands so thanks for clarifying that!
So...two big questions remain.
Question one. Is the wideband's voltage output linear or non-linear?
Question two. If it's a non-linear unit (likely), do these OBD programs have the right algorithm to determine the correct a/f ratio based on the voltage output?
If I remember correctly, the Innovative was non-linear. So when I'd use it, specifically with an Apexi Power-FC and the Datalogit system, We had to determine the slope of the curve and apply the right equation to make readings accurate across the voltage range since it was non-linear. You only did this once and it worked for all Innovative sensors but if you switched to say the AEM, you'd need a different algorithm. One of them was linear but can't remember which one.
Also, I just figured out how to log with the Fusion program (I think). Not as simple as just hitting record. Has a cool feature to upload your logs to Dropbox so I'll give that a whirl today.
I was not aware the precat sensors were true widebands so thanks for clarifying that!
So...two big questions remain.
Question one. Is the wideband's voltage output linear or non-linear?
Question two. If it's a non-linear unit (likely), do these OBD programs have the right algorithm to determine the correct a/f ratio based on the voltage output?
If I remember correctly, the Innovative was non-linear. So when I'd use it, specifically with an Apexi Power-FC and the Datalogit system, We had to determine the slope of the curve and apply the right equation to make readings accurate across the voltage range since it was non-linear. You only did this once and it worked for all Innovative sensors but if you switched to say the AEM, you'd need a different algorithm. One of them was linear but can't remember which one.
Also, I just figured out how to log with the Fusion program (I think). Not as simple as just hitting record. Has a cool feature to upload your logs to Dropbox so I'll give that a whirl today.
#4
Ok managed to do some logs today and export them. It's tough to get any WOT to redline in a big city during the day and anything above 3rd gear just wouldn't be prudent.
With that said, I did get some pulls to redline. I should have included rpm but I forgot but it basically went off the chart and I had a lot of 9.89's with most of the rev range being in the mid-10's. If that's indeed the case, I have quite a bit of power to gain with a tune.
I'm in the process of scheduling a baseline run on the dyno, hopefully next Monday. Should have a much clearer picture then.
With that said, I did get some pulls to redline. I should have included rpm but I forgot but it basically went off the chart and I had a lot of 9.89's with most of the rev range being in the mid-10's. If that's indeed the case, I have quite a bit of power to gain with a tune.
I'm in the process of scheduling a baseline run on the dyno, hopefully next Monday. Should have a much clearer picture then.
#5
Interesting.... Your AFRs are in the 9s. My car is stock and is normally low 11s at WOT. I agree that you have some power on the table when you lean out the AFRs to 11/12 something. (lean best torque)
I will baseline my car on the dyno before/after putting on a Stillen cat back exhaust and K&N panel filters.
If not too late, log the following when on the dyno:
-Coolant temp
-Intake air temp
-cylinder #1 timing
-RPM
-AFRs
-MAP (better breathing should give an atmospheric pressure (~29 inches vac)
I will do the same on my dyno next week and we can compare values.
Do you have an oil pressure gauge?
I will baseline my car on the dyno before/after putting on a Stillen cat back exhaust and K&N panel filters.
If not too late, log the following when on the dyno:
-Coolant temp
-Intake air temp
-cylinder #1 timing
-RPM
-AFRs
-MAP (better breathing should give an atmospheric pressure (~29 inches vac)
I will do the same on my dyno next week and we can compare values.
Do you have an oil pressure gauge?
#7
Ok I've got it set up to log four parameters which is the max.
-Actual A/F ratio
-RPM
-MAP
-IAT
I figure that'll be the most applicable since we're "testing" the intake system. I may try to switch up the parameters as I'd like to see the timing values. Being I have an IPL, they may be different from the standard ECU's timing. It'd be nice if it would record knock instances but I can't find it in the menu options.
I've got another program called BlueDriver and I can log five but it doesn't give me actual a/f ratio.
I could forego the a/f readout since they'll be using a wideband up the tailpipe (most likely) sensor.
It's supposed to be another 100 degree day tomorrow unfortunately and the humidity is up too.
-Actual A/F ratio
-RPM
-MAP
-IAT
I figure that'll be the most applicable since we're "testing" the intake system. I may try to switch up the parameters as I'd like to see the timing values. Being I have an IPL, they may be different from the standard ECU's timing. It'd be nice if it would record knock instances but I can't find it in the menu options.
I've got another program called BlueDriver and I can log five but it doesn't give me actual a/f ratio.
I could forego the a/f readout since they'll be using a wideband up the tailpipe (most likely) sensor.
It's supposed to be another 100 degree day tomorrow unfortunately and the humidity is up too.
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#10
Ok so despite the fact I had rpm, a/f, MAP, and IAT, it only recorded IAT and a/f. I had a/f and rpm on the same graph and IAT/MAP on the second yet none of the info for MAP and rpm was recored. WTF.
I've got a message out to OBD software to see if it's a bug.
I'd recored a/f and IAT's in the past but had them switched to something completely different this time around.
I've got a message out to OBD software to see if it's a bug.
I'd recored a/f and IAT's in the past but had them switched to something completely different this time around.
#11
Here's one of my logs. First is time, AIT, then AF. The others, with zeros, are listed as x, y axis.
0 105.8 0 0 0 0 0 0 0
0.415 105.8 14.64943 0 0 0 0 0 0
0.749 105.8 14.58379 0 0 0 0 0 0
2.548 105.8 14.64943 0 0 0 0 0 0
2.88 105.8 14.76686 0 0 0 0 0 0
3.235 105.8 14.92984 0 0 0 0 0 0
3.499 105.8 14.78249 0 0 0 0 0 0
3.802 105.8 14.59763 0 0 0 0 0 0
4.073 105.8 14.45609 0 0 0 0 0 0
4.435 105.8 14.36678 0 0 0 0 0 0
4.736 105.8 14.95976 0 0 0 0 0 0
5.002 105.8 15.47326 0 0 0 0 0 0
5.275 105.8 15.13703 0 0 0 0 0 0
5.638 105.8 14.52798 0 0 0 0 0 0
5.902 105.8 14.63737 0 0 0 0 0 0
6.177 105.8 14.28507 0 0 0 0 0 0
6.441 105.8 13.50053 0 0 0 0 0 0
6.804 104 13.82917 0 0 0 0 0 0
7.077 104 14.64541 0 0 0 0 0 0
7.351 104 14.4601 0 0 0 0 0 0
7.62 104 14.25515 0 0 0 0 0 0
7.974 104 14.62755 0 0 0 0 0 0
8.241 104 14.59763 0 0 0 0 0 0
8.548 104 14.78651 0 0 0 0 0 0
8.818 104 14.58156 0 0 0 0 0 0
9.24 104 14.64541 0 0 0 0 0 0
9.538 104 14.53378 0 0 0 0 0 0
9.804 104 14.39625 0 0 0 0 0 0
10.103 104 14.62933 0 0 0 0 0 0
10.492 104 14.57352 0 0 0 0 0 0
10.793 104 14.54584 0 0 0 0 0 0
11.061 104 14.36857 0 0 0 0 0 0
11.397 104 14.65345 0 0 0 0 0 0
11.788 102.2 14.62755 0 0 0 0 0 0
12.173 102.2 14.57352 0 0 0 0 0 0
12.449 102.2 14.59942 0 0 0 0 0 0
12.74 102.2 14.61147 0 0 0 0 0 0
13.101 102.2 14.5177 0 0 0 0 0 0
13.4 102.2 14.44626 0 0 0 0 0 0
13.67 102.2 14.4543 0 0 0 0 0 0
13.944 102.2 14.52172 0 0 0 0 0 0
14.307 102.2 14.52396 0 0 0 0 0 0
14.569 102.2 13.9725 0 0 0 0 0 0
14.9 102.2 14.38643 0 0 0 0 0 0
15.174 102.2 14.55566 0 0 0 0 0 0
15.533 102.2 14.45832 0 0 0 0 0 0
15.803 102.2 14.6213 0 0 0 0 0 0
16.071 102.2 14.85617 0 0 0 0 0 0
16.375 102.2 14.75079 0 0 0 0 0 0
16.735 102.2 14.43019 0 0 0 0 0 0
17.031 102.2 14.54762 0 0 0 0 0 0
17.31 102.2 14.37035 0 0 0 0 0 0
17.573 102.2 14.52172 0 0 0 0 0 0
17.937 102.2 14.50386 0 0 0 0 0 0
18.478 102.2 14.52798 0 0 0 0 0 0
18.925 102.2 14.07788 0 0 0 0 0 0
19.376 102.2 14.35651 0 0 0 0 0 0
19.82 102.2 14.56146 0 0 0 0 0 0
20.359 104 14.60165 0 0 0 0 0 0
20.842 104 14.54182 0 0 0 0 0 0
21.299 104 14.55566 0 0 0 0 0 0
21.77 104 14.51592 0 0 0 0 0 0
22.38 104 14.46993 0 0 0 0 0 0
22.853 104 11.59568 0 0 0 0 0 0
23.304 104 13.03079 0 0 0 0 0 0
23.759 104 12.85978 0 0 0 0 0 0
24.295 104 11.51396 0 0 0 0 0 0
24.739 104 11.79661 0 0 0 0 0 0
25.256 104 11.52602 0 0 0 0 0 0
25.739 104 10.95671 0 0 0 0 0 0
26.28 102.2 11.10986 0 0 0 0 0 0
26.727 102.2 10.69951 0 0 0 0 0 0
27.176 102.2 10.95671 0 0 0 0 0 0
27.62 102.2 10.54055 0 0 0 0 0 0
28.16 102.2 10.86294 0 0 0 0 0 0
28.613 102.2 10.47089 0 0 0 0 0 0
29.063 102.2 9.931498 0 0 0 0 0 0
29.55 102.2 9.931498 0 0 0 0 0 0
30.08 102.2 9.931498 0 0 0 0 0 0
30.563 102.2 9.931498 0 0 0 0 0 0
31.047 102.2 9.931498 0 0 0 0 0 0
31.49 102.2 9.931498 0 0 0 0 0 0
32.03 104 9.941321 0 0 0 0 0 0
32.486 104 29.13141 0 0 0 0 0 0
32.93 104 29.26269 0 0 0 0 0 0
33.413 104 29.26269 0 0 0 0 0 0
33.95 104 29.26269 0 0 0 0 0 0
34.47 104 29.26269
0 105.8 0 0 0 0 0 0 0
0.415 105.8 14.64943 0 0 0 0 0 0
0.749 105.8 14.58379 0 0 0 0 0 0
2.548 105.8 14.64943 0 0 0 0 0 0
2.88 105.8 14.76686 0 0 0 0 0 0
3.235 105.8 14.92984 0 0 0 0 0 0
3.499 105.8 14.78249 0 0 0 0 0 0
3.802 105.8 14.59763 0 0 0 0 0 0
4.073 105.8 14.45609 0 0 0 0 0 0
4.435 105.8 14.36678 0 0 0 0 0 0
4.736 105.8 14.95976 0 0 0 0 0 0
5.002 105.8 15.47326 0 0 0 0 0 0
5.275 105.8 15.13703 0 0 0 0 0 0
5.638 105.8 14.52798 0 0 0 0 0 0
5.902 105.8 14.63737 0 0 0 0 0 0
6.177 105.8 14.28507 0 0 0 0 0 0
6.441 105.8 13.50053 0 0 0 0 0 0
6.804 104 13.82917 0 0 0 0 0 0
7.077 104 14.64541 0 0 0 0 0 0
7.351 104 14.4601 0 0 0 0 0 0
7.62 104 14.25515 0 0 0 0 0 0
7.974 104 14.62755 0 0 0 0 0 0
8.241 104 14.59763 0 0 0 0 0 0
8.548 104 14.78651 0 0 0 0 0 0
8.818 104 14.58156 0 0 0 0 0 0
9.24 104 14.64541 0 0 0 0 0 0
9.538 104 14.53378 0 0 0 0 0 0
9.804 104 14.39625 0 0 0 0 0 0
10.103 104 14.62933 0 0 0 0 0 0
10.492 104 14.57352 0 0 0 0 0 0
10.793 104 14.54584 0 0 0 0 0 0
11.061 104 14.36857 0 0 0 0 0 0
11.397 104 14.65345 0 0 0 0 0 0
11.788 102.2 14.62755 0 0 0 0 0 0
12.173 102.2 14.57352 0 0 0 0 0 0
12.449 102.2 14.59942 0 0 0 0 0 0
12.74 102.2 14.61147 0 0 0 0 0 0
13.101 102.2 14.5177 0 0 0 0 0 0
13.4 102.2 14.44626 0 0 0 0 0 0
13.67 102.2 14.4543 0 0 0 0 0 0
13.944 102.2 14.52172 0 0 0 0 0 0
14.307 102.2 14.52396 0 0 0 0 0 0
14.569 102.2 13.9725 0 0 0 0 0 0
14.9 102.2 14.38643 0 0 0 0 0 0
15.174 102.2 14.55566 0 0 0 0 0 0
15.533 102.2 14.45832 0 0 0 0 0 0
15.803 102.2 14.6213 0 0 0 0 0 0
16.071 102.2 14.85617 0 0 0 0 0 0
16.375 102.2 14.75079 0 0 0 0 0 0
16.735 102.2 14.43019 0 0 0 0 0 0
17.031 102.2 14.54762 0 0 0 0 0 0
17.31 102.2 14.37035 0 0 0 0 0 0
17.573 102.2 14.52172 0 0 0 0 0 0
17.937 102.2 14.50386 0 0 0 0 0 0
18.478 102.2 14.52798 0 0 0 0 0 0
18.925 102.2 14.07788 0 0 0 0 0 0
19.376 102.2 14.35651 0 0 0 0 0 0
19.82 102.2 14.56146 0 0 0 0 0 0
20.359 104 14.60165 0 0 0 0 0 0
20.842 104 14.54182 0 0 0 0 0 0
21.299 104 14.55566 0 0 0 0 0 0
21.77 104 14.51592 0 0 0 0 0 0
22.38 104 14.46993 0 0 0 0 0 0
22.853 104 11.59568 0 0 0 0 0 0
23.304 104 13.03079 0 0 0 0 0 0
23.759 104 12.85978 0 0 0 0 0 0
24.295 104 11.51396 0 0 0 0 0 0
24.739 104 11.79661 0 0 0 0 0 0
25.256 104 11.52602 0 0 0 0 0 0
25.739 104 10.95671 0 0 0 0 0 0
26.28 102.2 11.10986 0 0 0 0 0 0
26.727 102.2 10.69951 0 0 0 0 0 0
27.176 102.2 10.95671 0 0 0 0 0 0
27.62 102.2 10.54055 0 0 0 0 0 0
28.16 102.2 10.86294 0 0 0 0 0 0
28.613 102.2 10.47089 0 0 0 0 0 0
29.063 102.2 9.931498 0 0 0 0 0 0
29.55 102.2 9.931498 0 0 0 0 0 0
30.08 102.2 9.931498 0 0 0 0 0 0
30.563 102.2 9.931498 0 0 0 0 0 0
31.047 102.2 9.931498 0 0 0 0 0 0
31.49 102.2 9.931498 0 0 0 0 0 0
32.03 104 9.941321 0 0 0 0 0 0
32.486 104 29.13141 0 0 0 0 0 0
32.93 104 29.26269 0 0 0 0 0 0
33.413 104 29.26269 0 0 0 0 0 0
33.95 104 29.26269 0 0 0 0 0 0
34.47 104 29.26269
#12
Ok I figured out what I did. I set up the graphing mode which is different from the CSV logging feature. That's set up in the settings menu. I'll do a few logs tomorrow on the way to work if I'm able.
I've got a bunch of stuff selected, everything you mentioned Sonic plus hp and oil temp (if that in fact is a supported function).
I've got a bunch of stuff selected, everything you mentioned Sonic plus hp and oil temp (if that in fact is a supported function).
#13
Ok, here's a screen shot of what the graphing feature looks like. I've got this one spot in my commute to work where I have to make a right hand turn while flooring it to merge with traffic that's going way too fast on an access road. Otherwise I die. So...a good spot to do a bit of logging.
The graph doesn't seem to match up though and I'm not sure if this is due to bluetooth latency or what. I've got my CSV files as well if someone wants to take a look.
This one's a bit better since it's horizontal and more spread out.
The graph doesn't seem to match up though and I'm not sure if this is due to bluetooth latency or what. I've got my CSV files as well if someone wants to take a look.
This one's a bit better since it's horizontal and more spread out.
#14
Another log today just for the fun of it. Was hoping I could see actual a/f for both O2's on either bank but no dice. Didn't see anything to record MAF voltage to make sure both are producing close to the same voltage at any particular rpm point. Leaning hard towards getting an ECUtek so I can log various parameters accurately. I'm getting three data points per second, not nearly enough.
Sitting at about 27inHg peak high up in the rev range.
Sitting at about 27inHg peak high up in the rev range.
#15
Depending on the "ELM327" device you have, you will have different scanning speeds. My first one gives me an average of 25 per second, the second one I bought last month (looks the same) gives me 10 samples per second.
You should buy the "Advanced EX for Infiniti" Torque plug in:
https://play.google.com/store/apps/d...eeo.inadvanced
Here are the items I logged during my 6 dyno pulls (yesterday) and a few passes down the quarter mile (today):
- [IADV] Fuel Base Pulse Width(ms)
- [IADV] Fuel Temperature(°C)
- [IADV] Ignition Timing Adv(°)
- [IADV] Injector Duty Cycle(%)
- [IADV] Injector Pulse Width (B1)(ms)
- [IADV] Injector Pulse Width (B2)(ms)
- [IADV] MAF Volts (B1)(V)
- [IADV] MAF Volts (B2)(V)
- [IADV] Mass Air Flow(gm/s)
- [IADV] VVT Oil Temperature(°C)
- Accelerator PedalPosition D(%)
- Air Fuel Ratio(Measured)(:1)
- Engine Coolant Temperature(°C)
- Engine Load(Absolute)(%)
- Engine RPM(rpm)
- Intake Manifold Pressure(kpa)
- O2 Sensor1 wide-range Voltage
- Speed (OBD)(km/h)
I am back to the drag strip tomorrow. Today's race was cancelled part way though due to a drag bike crashing / air ambulance.
You should buy the "Advanced EX for Infiniti" Torque plug in:
https://play.google.com/store/apps/d...eeo.inadvanced
Here are the items I logged during my 6 dyno pulls (yesterday) and a few passes down the quarter mile (today):
- [IADV] Fuel Base Pulse Width(ms)
- [IADV] Fuel Temperature(°C)
- [IADV] Ignition Timing Adv(°)
- [IADV] Injector Duty Cycle(%)
- [IADV] Injector Pulse Width (B1)(ms)
- [IADV] Injector Pulse Width (B2)(ms)
- [IADV] MAF Volts (B1)(V)
- [IADV] MAF Volts (B2)(V)
- [IADV] Mass Air Flow(gm/s)
- [IADV] VVT Oil Temperature(°C)
- Accelerator PedalPosition D(%)
- Air Fuel Ratio(Measured)(:1)
- Engine Coolant Temperature(°C)
- Engine Load(Absolute)(%)
- Engine RPM(rpm)
- Intake Manifold Pressure(kpa)
- O2 Sensor1 wide-range Voltage
- Speed (OBD)(km/h)
I am back to the drag strip tomorrow. Today's race was cancelled part way though due to a drag bike crashing / air ambulance.