Best G37 Gauges! (Turbo, Engine, Speed, Temp)
04-20-2010, 02:25 PM
#61
OBDII. I'm taking the average of both stock wideband AFR sensors. PLX devices also makes a AFR sensor that you can attach to the system. But why add something that's already there?
I'm also getting the following parameters from OBDII:
-Intake Air Temp (BTW, the GTM intercooler does an amazing job. The intake air temp stays around outside temperature)
-Water Temp
-Engine RPM
-Mass Air Flow
-Timing Advance
-Engine Load
-Vehicle Speed
-Accelerator Pedal Position
I'm also getting the following parameters from OBDII:
-Intake Air Temp (BTW, the GTM intercooler does an amazing job. The intake air temp stays around outside temperature)
-Water Temp
-Engine RPM
-Mass Air Flow
-Timing Advance
-Engine Load
-Vehicle Speed
-Accelerator Pedal Position
04-20-2010, 05:36 PM
#63
Because the stock O2 sensors are not calibrated for the numbers you are concerned about. The stock sensors are looking at the AFR while in closed loop. They are most likely going to see 14.0 +/- 1 and the engine needs this information (amoung other things) to adjust fuel and spark. As soon as you get on it hard, the computer resorts to an open loop and the O2 sensors play no part. This is the time you are concerned about your AFR, you couldn't care less in closed loop. While in open loop you need to be watching the AFR because this is your only true indication if you are running rich or lean. The stock sensors are not widebands. They may read a number but they are not accurate and should never be relied on. A wideband is worth it's weight in gold if you're going to heavily mod your engine (which you have).
What would be a really really neat test (at least to me) is getting the PLX sensor (they use a Bosch LSU 4.2) and hooking it up and then compare it to what the stock sensors are reading at the same time. I believe the way you have it set up right now, you'ld be able to do that and record it to your computer. That would be something...
There is another test that you are set uo to do right now that would answer A LOT of questions for me if you're willing to datalog two parameters.
-Accelerator Pedal Position and Throttle Blade Position. You should have both those parameters coming off your OBDII. Some people are saying the throttle blade is wide open all the time and the VVEL is acting like the throttle blade. I want to see it to believe it. If you log both, I bet you will be amazed with the results.
04-20-2010, 08:51 PM
#64
Administrator
Because the stock O2 sensors are not calibrated for the numbers you are concerned about. The stock sensors are looking at the AFR while in closed loop. They are most likely going to see 14.0 +/- 1 and the engine needs this information (amoung other things) to adjust fuel and spark. As soon as you get on it hard, the computer resorts to an open loop and the O2 sensors play no part. This is the time you are concerned about your AFR, you couldn't care less in closed loop. While in open loop you need to be watching the AFR because this is your only true indication if you are running rich or lean. The stock sensors are not widebands. They may read a number but they are not accurate and should never be relied on. A wideband is worth it's weight in gold if you're going to heavily mod your engine (which you have).
What would be a really really neat test (at least to me) is getting the PLX sensor (they use a Bosch LSU 4.2) and hooking it up and then compare it to what the stock sensors are reading at the same time. I believe the way you have it set up right now, you'ld be able to do that and record it to your computer. That would be something...
There is another test that you are set uo to do right now that would answer A LOT of questions for me if you're willing to datalog two parameters.
-Accelerator Pedal Position and Throttle Blade Position. You should have both those parameters coming off your OBDII. Some people are saying the throttle blade is wide open all the time and the VVEL is acting like the throttle blade. I want to see it to believe it. If you log both, I bet you will be amazed with the results.
-Accelerator Pedal Position and Throttle Blade Position. You should have both those parameters coming off your OBDII. Some people are saying the throttle blade is wide open all the time and the VVEL is acting like the throttle blade. I want to see it to believe it. If you log both, I bet you will be amazed with the results.
04-20-2010, 09:44 PM
#65
Because the stock O2 sensors are not calibrated for the numbers you are concerned about. The stock sensors are looking at the AFR while in closed loop. They are most likely going to see 14.0 +/- 1 and the engine needs this information (amoung other things) to adjust fuel and spark. As soon as you get on it hard, the computer resorts to an open loop and the O2 sensors play no part. This is the time you are concerned about your AFR, you couldn't care less in closed loop. While in open loop you need to be watching the AFR because this is your only true indication if you are running rich or lean. The stock sensors are not widebands. They may read a number but they are not accurate and should never be relied on. A wideband is worth it's weight in gold if you're going to heavily mod your engine (which you have).
What would be a really really neat test (at least to me) is getting the PLX sensor (they use a Bosch LSU 4.2) and hooking it up and then compare it to what the stock sensors are reading at the same time. I believe the way you have it set up right now, you'ld be able to do that and record it to your computer. That would be something...
There is another test that you are set uo to do right now that would answer A LOT of questions for me if you're willing to datalog two parameters.
-Accelerator Pedal Position and Throttle Blade Position. You should have both those parameters coming off your OBDII. Some people are saying the throttle blade is wide open all the time and the VVEL is acting like the throttle blade. I want to see it to believe it. If you log both, I bet you will be amazed with the results.
What would be a really really neat test (at least to me) is getting the PLX sensor (they use a Bosch LSU 4.2) and hooking it up and then compare it to what the stock sensors are reading at the same time. I believe the way you have it set up right now, you'ld be able to do that and record it to your computer. That would be something...
There is another test that you are set uo to do right now that would answer A LOT of questions for me if you're willing to datalog two parameters.
-Accelerator Pedal Position and Throttle Blade Position. You should have both those parameters coming off your OBDII. Some people are saying the throttle blade is wide open all the time and the VVEL is acting like the throttle blade. I want to see it to believe it. If you log both, I bet you will be amazed with the results.
I dont understand why you guy insist that the stock O2 sensor is not a wideband. Referring to the factory service manual, here is what the O2 sensor output graph looks like:
It is quite clear that our O2 sensor is capable of measuring 10-20 afr. Lets compare it to a 2004 G35, where the O2 sensor is indeed not a wideband:
What you said about 14.7 +-1 is true for the old g35 sensor.
During open loop, even though the ECM might not rely on the O2 sensor to adjust fuel and spark, it doesn't mean the O2 sensor just stops measuring AFR altogether. Here is a log of AFR I did a while ago:
See the range that the O2 sensor is outputting? You can see WOT runs when the AFR dips down to ~11.
I'd love to compare the PLX wideband and stock O2 sensors for you. Just send a PLX sensor my house, I'll install and report back within 2 days
04-20-2010, 11:23 PM
#67
Administrator
It might be not-so-narrow-band but it surely isn't accurate, see for yourself
It's far from linear, predicting real AF from voltage reading will get messy, on the Bosch sensor however, it's linear.. and that's why you need it.. Linear makes calculating AF ratio a simple and accurate task
It's far from linear, predicting real AF from voltage reading will get messy, on the Bosch sensor however, it's linear.. and that's why you need it.. Linear makes calculating AF ratio a simple and accurate task
04-21-2010, 12:42 AM
#68
No worries, I'm not calculating the AFR from the voltages. The stock ECU uses many different points on the graph to extrapolate the AFR correctly. The ECU then converts the extrapolated AFR into LAMBDA. Using this LAMBDA, I reconvert the values into AFR.
If anyone is familiar with Cipher, they have a tool for Wideband Conversion. You select the expected voltages for given AFRs. Using 10 different points on the graph, you can accurately extrapolate the AFR from voltages. This is what the ECU does.
I totally agree that a Bosch AFR widewand more be accurate, but I dont believe it is absolutely necessary. The stock O2 sensors might be off by +- 0.2 AFR. But is anyone going to panic if the AFR is 10.6 instead of 10.4?
If anyone is familiar with Cipher, they have a tool for Wideband Conversion. You select the expected voltages for given AFRs. Using 10 different points on the graph, you can accurately extrapolate the AFR from voltages. This is what the ECU does.
I totally agree that a Bosch AFR widewand more be accurate, but I dont believe it is absolutely necessary. The stock O2 sensors might be off by +- 0.2 AFR. But is anyone going to panic if the AFR is 10.6 instead of 10.4?
04-21-2010, 12:51 AM
#69
Me! If I'm running 12.9, I know I'm running lean and on the verge of the danger zone and may need to add some fuel to the next tune. However if I was really running 13.1, I would have gotten off the gas immediately because I had already crossed the line.
04-21-2010, 12:55 AM
#70
And also, I think gauges are good tools to help you see how your car is running, but you're not going to stare at the AFR gauge during WOT every time. Unless you're doing data logging, it's hard to determine your exact AFR at WOT. Most of the time, I'm more worried about switch gear fast enough and watching the road, rather than looking at the gauge. I would not be able to notice that the AFR is 10.9 instead of 10.3, or something like that. However, if I'm at 13 or something during WOT, then something is obviously wrong. For that purpose, I feel the stock sensors are sufficient.
04-21-2010, 12:57 AM
#71
You live life on the dangerous side. lol You, my friend, should get tuned! How do you have fun during WOT when youre constantly worried about your AFR?
My case is different from yours, because you already know you are running lean. Sam tuned my car very conservatively and very consistently. If there is something wrong (clogged injector, bad fuel pump, leak), the AFR would change dramatically. So I dont think there is a need to scrutinize the AFR with every run.
Last edited by Modme; 04-21-2010 at 01:06 AM.
