Advancement of fuel delivery?
- Thread starter Alky V6
- Start date
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I'm glad to see you're getting something out of this write up. I can only hope you're able to put some of this information towards your own project.
I have to explain something so I don't confuse everyone. I'm using an Electromotive TEC3r EMS. Unfortunately, the graphing feature is lacking with that system. I use the Motec software only to check my tables using their excellent graphing features. I just plug my numbers into their program and examine the table with much better clarity and view angle choices. I know that some people ignore the graphing feature of their software, but I've gotten very used to using it to gain more insight into what the engine wants. It's like looking directly into the soul of the engine. I think Motec understands that very well and that's why their graphing is so superior to others.
To answer your question, the TEC system datalogs at a max rate of 25 frames per second. Up to this point, I have not realized any need for more frames per second. I have used the lesser frames per second choices (5, 10) and found that 25 frames per second is much better from a tuners stand point.
If you're talking about how fast the system adjusts to changes in a/f (O2 correction), I have no experience with the Motec system. With the TEC unit, the O2 parameters such as authority range, how quickly or slowly, and how large or small a step of correction is made are all adjustable. Correction speed is also dependant on the condition and speed of the O2 or a/f sensor and where in the exhaust system it's located. With my system I've found that with the datalog sample rate set at 25 frames per second, and at 2500 rpm, the a/f sensor reading lags behind about 1 to 3 frames.
If you'll notice in the datalogs, I'm not using O2 correction. It's turned off. That's the parameter labeled CR. In the AFR parameter (air/fuel ratio) and EGO (O2 volts) you can see a couple of lean spikes. That's from the nitrous system and aux fuel transitions. In the TFPW (Total Fuel Pulse Width) parameter you can see about three rich spikes. The first large spike is the acceleration enrichment (accelerator pump) from going WOT and the other two are programmed in to fight the lean spikes during the other system transitions. The small one between the two large spikes is when the nitrous turns on and the last large spike in fuel is when the aux fuel system turns on.
In ADV (ignition advance) you can see the ignition retard that occurs during nitrous activation.
In DUTY (injector duty cycle) you can see how close to max duty cycle (85%) the 160 lbs/hr electronic injectors are during most of the run.
Notice in the EGO screen how the volts go very low (10.17:1 rich) after the last large lean spike (aux fuel turning on). From that point to the end of the run you'll notice the EGO reading very steadily ramping up to a higher reading (10.7:1) by the end of the run. Now notice in the PWON (injector on time in milliseconds) screen how the pulse width on time basically is flat line for the large duration of the run through 2nd and 3rd. You can judge where 2nd and 3rd is by studying the RPM screen and looking for the rpm drops due to the shifts. The last drop in rpm being me getting off the throttle at the finish line [notice the TPS (throttle position sensor) reading]. Keep in mind that my O2 readings are programmed to readout in gasoline numbers.
The sharp rise in MAP (manifold absolute pressure) at the start of the run is where the nitrous turns on. Notice how quickly and smoothly the map rises and spikes before the shift point for first gear.
The rpm also rises fairly smoothly in spite of all the fueling transitions that are occurring. This particular datalog showed some roughness in the rpm before the shift into second. Some of that may be due to the boost controller working on that boost spike that went past the target boost of 24 psi by about 4 to 5 psi. You'll also notice the boost rising a bit just after each shift. You don't realize what it took to get the rpm rise as smooth as it is.
The small rpm rise about 1/3 the way across the rpm screen was me bringing the rpm up at staging, going WOT, releasing the transbrake button on the first amber, waiting for the delay box to activate the nitrous system and finally the transbrake release about .47 seconds after the nitrous was turned on. I'll double check that .47 figure. I know I was playing around with the delay points a lot.
In ADV (ignition advance) you can see the ignition retard that occurs during nitrous activation.
In DUTY (injector duty cycle) you can see how close to max duty cycle (85%) the 160 lbs/hr electronic injectors are during most of the run.
Notice in the EGO screen how the volts go very low (10.17:1 rich) after the last large lean spike (aux fuel turning on). From that point to the end of the run you'll notice the EGO reading very steadily ramping up to a higher reading (10.7:1) by the end of the run. Now notice in the PWON (injector on time in milliseconds) screen how the pulse width on time basically is flat line for the large duration of the run through 2nd and 3rd. You can judge where 2nd and 3rd is by studying the RPM screen and looking for the rpm drops due to the shifts. The last drop in rpm being me getting off the throttle at the finish line [notice the TPS (throttle position sensor) reading]. Keep in mind that my O2 readings are programmed to readout in gasoline numbers.
The sharp rise in MAP (manifold absolute pressure) at the start of the run is where the nitrous turns on. Notice how quickly and smoothly the map rises and spikes before the shift point for first gear.
The rpm also rises fairly smoothly in spite of all the fueling transitions that are occurring. This particular datalog showed some roughness in the rpm before the shift into second. Some of that may be due to the boost controller working on that boost spike that went past the target boost of 24 psi by about 4 to 5 psi. You'll also notice the boost rising a bit just after each shift. You don't realize what it took to get the rpm rise as smooth as it is.
The small rpm rise about 1/3 the way across the rpm screen was me bringing the rpm up at staging, going WOT, releasing the transbrake button on the first amber, waiting for the delay box to activate the nitrous system and finally the transbrake release about .47 seconds after the nitrous was turned on. I'll double check that .47 figure. I know I was playing around with the delay points a lot.
The last large spike in pulse width (you can see the large wall of fueling in the middle of the fuel map that I posted) that's used to combat the last large lean spike caused by the activation of the aux fuel system, would first appear as though there's more work to be done to get that lean spike more under control. The shape of that wall of fueling is amazingly touchy. The height, depth and rise of it are critical. The rise being the hardest parameter. The length from side to side is just to make sure that the extra fueling is there no matter the rpm that the engine is at when it crosses over the wall. The shape of the wall and the resulting lean spike that's recorded in the datalog are as good as it gets. As it is, it results in a relatively smooth rpm rise during launch. Any slight changes to the wall seems to upset the engine and ends up resulting in a not-so-smooth rpm rise, and can even result in dips in rpm during launch.
six shooter
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Thanks for the narration on the logs. Very interesting stuff to review.
Thanks for the narration on the logs. Very interesting stuff to review.
I knew you'd like it.
If anyone has any questions, fire away.
Are you not using O2 correction because of the time it takes to correct or are you just that good??I always leave positive correction on just in case there's pump problems.
Scott Wile
I've got the map so close that just a 1% correction pulls the mixture farther off target than when I leave the correction off. Another thing that upsets the correction is the large lean spikes that are inherent with my fueling system. When the sensor sees one of the lean spikes it throws more fuel, even if it is just 1%. Then immediately the reading goes very rich and the sensor says, "oops" and pulls the fuel out. 2% this time because of the 1% rich and 1% lean authority given to the sensor. The engine and datalogs are much more stable when I leave the correction off. So far, weather changes has not been a problem.
I was thinking the same thing.
It's not really a big deal with methanol. The tuning range is so wide, it's much harder to get in trouble compared with gasoline.
six shooter
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Ok, I can't read the time cursor, so is this close? RPM approx 2400ish with the N20 off - T-brake on. N20 on and RPM 5500-6000ish. T-brake still on? I guess my question would be does the N20 raise the stall speed of the converter , or is the RPM rise off the T-brake?
Ok, I can't read the time cursor, so is this close? RPM approx 2400ish with the N20 off - T-brake on. N20 on and RPM 5500-6000ish. T-brake still on? I guess my question would be does the N20 raise the stall speed of the converter , or is the RPM rise off the T-brake?
There is a glitch with the TEC3r system datalogging. If I do internal datalogging at a lower frame per second you get accurate time stamping, so they say. I do external datalogging to my laptop at a higher frame per second (25) and the time stamps are inaccurate. I have yet to figure out by how far off the time stamp is and come up with a factor to use to correct the time stamping. Sorry I didn't mention that.
The nitrous does immediately raise the stall speed. Keep in mind that for any given torque converter the stall speed will be dependant on the torque level applied to the torque converter. Since nitrous is basically torque in a blue bottle, the more you inject, the higher you can instantly raise the stall speed of a given torque converter.
Recall that I stated that the cursor line was put at the point where the nitrous was just turning off. You can see in the ADV line that the timing is getting ready to come back in from nitrous-retard. At that point the transbrake is still on and about to be released.
I know it's hard to tell when the transbrake does come off judging by the rpm and map screens.
six shooter
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10-4 , Thanks again Donnie !:biggrin:
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