Air/fuel ratio confusion
10-22-2014, 10:36 AM
#21
Safety Car
10-22-2014, 10:36 AM
#22
Drifting
Thread Starter
I initially thought that because I usually roll into the throttle and, thus, I enter PE before I am actually WOT that I was getting a initial rich condition that took a "while" for "soaked" WB to correct...but HPT doesn't seem to reflect this.
10-22-2014, 01:37 PM
#23
ISIS SUCKS FAT CHOAD
His car is -98, thus less PID's and less framerate than -99 and newer PCM's.
Activate Table Display in Scanner, hit F1 and you'll find out more about logging speed. -97..98 has 24 byte max, newer C5 PCM's have 48 byte max.
Furthermore, if you compare PLX and for example Innovate Wideband, they both have about 14.8...15 AFR at the same voltage output (around 2.5 volts), but whereas PLX goes only as low as 10 AFR (at 0 volts), Innovate goes all the way to 7.x AFR (at 0 volts). What this means is that if you have wrong WB selected in the Table Display, it may show the right AFR at stoich (around 14.7...), but it will be off at WOT.
For the OP, take a screenshot from your Table Display. It needs to have correct WB selected.
Activate Table Display in Scanner, hit F1 and you'll find out more about logging speed. -97..98 has 24 byte max, newer C5 PCM's have 48 byte max.
Furthermore, if you compare PLX and for example Innovate Wideband, they both have about 14.8...15 AFR at the same voltage output (around 2.5 volts), but whereas PLX goes only as low as 10 AFR (at 0 volts), Innovate goes all the way to 7.x AFR (at 0 volts). What this means is that if you have wrong WB selected in the Table Display, it may show the right AFR at stoich (around 14.7...), but it will be off at WOT.
For the OP, take a screenshot from your Table Display. It needs to have correct WB selected.
10-22-2014, 03:48 PM
#25
Drifting
Thread Starter
As I've mentioned in this thread, in the summer I've seen my WB gauge display AFR values close to what I expected to see (in agreement with HP Tuners) but when its cool out (50-60 degrees) I don't.
When the ambient temp is cool the motor makes more power, obviously, than when its hot and, likewise, the tires get less traction.
I always roll into the throttle in 2nd starting at around 40mph to try to keep the tires under the car. When its cold out, I roll into the throttle slower.
Just a little while ago, on my lunch break, I dropped the tire pressure on my big 345/35/18s (not drag radials) down to 20 psi in an effort to get more traction.
I entered the freeway entrance ramp, waited until about 45 mph, and punched the throttle. The car fish tailed all over the place but I saw my gauge hanging around 11.2-11.3 until I lifted the throttle.
Maybe it is the slow gauge trying to average what its seeing. When I roll into the throttle slowly, it enters PE before its "ready" and is richer than it needs to be. And since my 40-70 pulls don't last long it never really catches up?
I'm going to try a little 3rd gear pull later on the way home, to see what happens.
When the ambient temp is cool the motor makes more power, obviously, than when its hot and, likewise, the tires get less traction.
I always roll into the throttle in 2nd starting at around 40mph to try to keep the tires under the car. When its cold out, I roll into the throttle slower.
Just a little while ago, on my lunch break, I dropped the tire pressure on my big 345/35/18s (not drag radials) down to 20 psi in an effort to get more traction.
I entered the freeway entrance ramp, waited until about 45 mph, and punched the throttle. The car fish tailed all over the place but I saw my gauge hanging around 11.2-11.3 until I lifted the throttle.
Maybe it is the slow gauge trying to average what its seeing. When I roll into the throttle slowly, it enters PE before its "ready" and is richer than it needs to be. And since my 40-70 pulls don't last long it never really catches up?
I'm going to try a little 3rd gear pull later on the way home, to see what happens.
10-22-2014, 07:51 PM
#26
Le Mans Master
I didn't read the whole thread but one thing to keep in mind. I have my wideband hooked to an aeroforce gauge. I unplug the gauge when I hook the wideband to HPT. I have on occasion left HPT plugged in while using the gauge and noticed the AFR is off when they are both connected. If you have them both connected at the same time I would try running them one at a time and compare like that.
10-22-2014, 08:09 PM
#27
Drifting
Thread Starter
I didn't read the whole thread but one thing to keep in mind. I have my wideband hooked to an aeroforce gauge. I unplug the gauge when I hook the wideband to HPT. I have on occasion left HPT plugged in while using the gauge and noticed the AFR is off when they are both connected. If you have them both connected at the same time I would try running them one at a time and compare like that.
Last edited by reactor2; 10-22-2014 at 08:17 PM.
10-22-2014, 08:17 PM
#28
Drifting
Thread Starter
So I made a couple of 2nd gear runs this evening and I noticed that if I just hit the pedal and got limited wheel spin (50mph up) I saw what I expected on the gauge 11.2-11.4.
Question:
About how much leaner can I expect on a good 3rd gear pull, where there is more load on the engine?
Question:
About how much leaner can I expect on a good 3rd gear pull, where there is more load on the engine?
10-22-2014, 09:34 PM
#29
ISIS SUCKS FAT CHOAD
11.2-11.4 is plenty safe. Just to give you a safe and reasonable AFR target, if it was my car, id shoot for an 11.5 AFR under your WOt high load situations.
Sure you can go a bit leaner could probably bring it out to 12.0 if you wanted but why risk it.
Sure you can go a bit leaner could probably bring it out to 12.0 if you wanted but why risk it.
10-23-2014, 08:49 AM
#30
Tech Contributor
I'm just scanning through this whole thing.....based on that.
Just because HPT has it set up for you doesn't mean it's right. Just because it's right while cruising doesn't mean HPT is set up right. 2 things come in play. Slope and offset. I verify these are correct before tuning. I write custom PIDs most of the time because they disagree so much.
Just because HPT has it set up for you doesn't mean it's right. Just because it's right while cruising doesn't mean HPT is set up right. 2 things come in play. Slope and offset. I verify these are correct before tuning. I write custom PIDs most of the time because they disagree so much.
10-23-2014, 09:27 AM
#31
Drifting
Thread Starter
I'm just scanning through this whole thing.....based on that.
Just because HPT has it set up for you doesn't mean it's right. Just because it's right while cruising doesn't mean HPT is set up right. 2 things come in play. Slope and offset. I verify these are correct before tuning. I write custom PIDs most of the time because they disagree so much.
Just because HPT has it set up for you doesn't mean it's right. Just because it's right while cruising doesn't mean HPT is set up right. 2 things come in play. Slope and offset. I verify these are correct before tuning. I write custom PIDs most of the time because they disagree so much.
10-24-2014, 01:12 PM
#32
ISIS SUCKS FAT CHOAD
I'm just scanning through this whole thing.....based on that.
Just because HPT has it set up for you doesn't mean it's right. Just because it's right while cruising doesn't mean HPT is set up right. 2 things come in play. Slope and offset. I verify these are correct before tuning. I write custom PIDs most of the time because they disagree so much.
Just because HPT has it set up for you doesn't mean it's right. Just because it's right while cruising doesn't mean HPT is set up right. 2 things come in play. Slope and offset. I verify these are correct before tuning. I write custom PIDs most of the time because they disagree so much.
Is there a way to look at the slope (rise/run) and offset in the pre programmed PID's HP tuners has?
The slope and voltage offset I came up with in one of my earlier post was made using the data that I found from PLX.
On that note I do remember my LC1 not reading correctly using the pre programmed PID in HPT.
10-24-2014, 01:23 PM
#33
ISIS SUCKS FAT CHOAD
Ok after looking I don't think there's a way to adjust a preloaded HpT Wideband PID.
Try this and push the +10 around if needed until HPT matches your gauge.
https://www.corvetteforum.com/forums...1&d=1414171304
Try this and push the +10 around if needed until HPT matches your gauge.
https://www.corvetteforum.com/forums...1&d=1414171304