Final Questions Before Installing VAFC-II
03-30-2010, 09:20 AM
#1
Final Questions Before Installing VAFC-II
Hey all,
I'm planning on taking this weekend to finally install my VAFC-II now that the weather's starting to break.
I've dug through most of the stickies on installing the VAFC on our cars (specifically the 5.5 for me), but I have a few questions that either weren't answered, or that were answered in a sticky that has a broken link. So, here goes...
First, knowing that the VAFC-II has two power and two grounding points, is it possible to run both power wires to one single pin on the ECU? Or would I be better off sticking with two separate pins? Also, being that ground is universal, I was wondering if it would be a problem grounding the VAFC-II to the body of the car somewhere instead of to the ECU itself.
Second, as far as final tuning, does the VAFC fix the AFR by itself based on the TPS sensor, or will it still need a solid tune? I'm planning on a dyno tune in a few weeks after everything is put together since I'm putting a WBO2 off for now. I'm figuring I answered my own question, but I thought I'd double-check.
Finally, correct me if I'm wrong, but the open loop doesn't begin for the 5.5 until you reach 3000 RPM, right? Knowing that, would it be in my best interest to work from 3000 RPM up on the LVT and then map the rest of the way up on the HVT setting? I'm running stock injectors and MAF housing.
Thanks, guys.
I'm planning on taking this weekend to finally install my VAFC-II now that the weather's starting to break.
I've dug through most of the stickies on installing the VAFC on our cars (specifically the 5.5 for me), but I have a few questions that either weren't answered, or that were answered in a sticky that has a broken link. So, here goes...
First, knowing that the VAFC-II has two power and two grounding points, is it possible to run both power wires to one single pin on the ECU? Or would I be better off sticking with two separate pins? Also, being that ground is universal, I was wondering if it would be a problem grounding the VAFC-II to the body of the car somewhere instead of to the ECU itself.
Second, as far as final tuning, does the VAFC fix the AFR by itself based on the TPS sensor, or will it still need a solid tune? I'm planning on a dyno tune in a few weeks after everything is put together since I'm putting a WBO2 off for now. I'm figuring I answered my own question, but I thought I'd double-check.
Finally, correct me if I'm wrong, but the open loop doesn't begin for the 5.5 until you reach 3000 RPM, right? Knowing that, would it be in my best interest to work from 3000 RPM up on the LVT and then map the rest of the way up on the HVT setting? I'm running stock injectors and MAF housing.
Thanks, guys.
03-30-2010, 09:35 AM
#2
Might want to do a little more reading on the VAFC-II. I believe in the VAFC-II manual it says you can use the same power wire as long as the connections are 1 inch apart. A ground is a ground. You can use the body or the ECU. It will not tune itself so you'll either need to dyno tune and or street tune the car to get things perfect. Im not 100% sure but I believe open loop is 3000 rpm and WOT.
03-30-2010, 09:40 AM
#3
If I remember correctly, I SOLDERED both of the power wires from the VAFC to the same lead on the ECU harness. Just make sure you solder it properly and give it a good connection.
As far as grounding, I would try to avoid grounding it to the chassis of the car. Even though it is technnically "ground", there is some resistance induced by the car so you are better off grounding it to the same ground that the ECU uses.
Remember that the VAFC is changing the MAF voltage with respect to ground, so it is important that the VAFC and ECU share the same reference voltage (ground).
And the VAFC does not tune itself based on TPS. You have two options:
1. Take it to a dyno shop who will tune the VAFC for you. They will do a couple of pulls and get a baseline reading, then make the corrections on the VAFC and do a couple more pulls to verify the corrections.
2. Get a wide band o2 like the Innovate LC1 (I recommend this). This will allow you to do your own pulls on the street and tune it yourself. This is better because you can always make adjustments when you add new mods instead of having to go back to the dyno shop every time.
And as far as open loop goes, there are two triggers.
1. 3000 RPM -OR-
2. 40% TPS (approx)
This means that you can be at 1000rpm and floor it, and this will cause the ECU to go into open loop. This also means that you can be at 3000RPM at 10% throttle, and the ECU will go into open loop.
So set your low throttle to 39% and high throttle to 90%. This means that anything below 39% uses the low throttle map (which I left all corrections at 0 because the ECU will be in closed loop) and that anything between 39% and 90% is an interpolation of your high and low throttle map and anything over 90% is purely the high throttle map.
I just configured the high throttle map because I didn't need the VAFC to make any corrections below 39% throttle.
A good example of how your LVT-HVT settings should be configured is outlined in this post:
As far as grounding, I would try to avoid grounding it to the chassis of the car. Even though it is technnically "ground", there is some resistance induced by the car so you are better off grounding it to the same ground that the ECU uses.
Remember that the VAFC is changing the MAF voltage with respect to ground, so it is important that the VAFC and ECU share the same reference voltage (ground).
And the VAFC does not tune itself based on TPS. You have two options:
1. Take it to a dyno shop who will tune the VAFC for you. They will do a couple of pulls and get a baseline reading, then make the corrections on the VAFC and do a couple more pulls to verify the corrections.
2. Get a wide band o2 like the Innovate LC1 (I recommend this). This will allow you to do your own pulls on the street and tune it yourself. This is better because you can always make adjustments when you add new mods instead of having to go back to the dyno shop every time.
And as far as open loop goes, there are two triggers.
1. 3000 RPM -OR-
2. 40% TPS (approx)
This means that you can be at 1000rpm and floor it, and this will cause the ECU to go into open loop. This also means that you can be at 3000RPM at 10% throttle, and the ECU will go into open loop.
So set your low throttle to 39% and high throttle to 90%. This means that anything below 39% uses the low throttle map (which I left all corrections at 0 because the ECU will be in closed loop) and that anything between 39% and 90% is an interpolation of your high and low throttle map and anything over 90% is purely the high throttle map.
I just configured the high throttle map because I didn't need the VAFC to make any corrections below 39% throttle.
A good example of how your LVT-HVT settings should be configured is outlined in this post:
It has come to my attention that some people could use a little extra help when setting up the VAFC-II for the Maxima. Many are following my recommendations for getting it over the SAFC-II, which I find encouraging, but I suppose I need to clarify more of the details.
The reasoning for getting the V over the S really has nothing to do with it's 'vtec control' or in our case 'rpm switch'. That part isn't a direct wire setup anyway. And it certainly would have nothing to do with attempting to control the VTCs on the VQ35, as some mistakenly suspect.
It's really all about the NE points for setting up the fuel corrections. The SAFC-II has a twelve point by two point map (12x2) which means you can setup 12 rpm points throughout the rev range and 2 throttle points for correction. Anything in between your specified RPM and throttle points is interpolated . The SAFC-II can also be manually switched to a second data file or map to be used with Nitrous or some other more or less aggressive tuning parameters you might need.
The VAFC-II essentially uses both of these 12x2 maps together, effectively making it a 24x2. But it has to be triggered to select between these two maps by a Hvt and Lvt setting (12x2 high vtec, 12x2 low vtec).
Now for the example setups:
So for most of these cars that can only rev to 6500 or 6600, we would set the Lvt to Hvt setting at 4200rpm and the Hvt to Lvt at 4100 (for some reason it wont let you make them the same). Doing this means that the VAFC-II will switch over from one 12 point map to the other 12 point map at 4200rpm. Now you'll need to setup the Lvt NE (RPM) points, obviously you'll want to end the Lvt points at or before 4200rpm because that is where you just set the crossover. If you set Lvt points past your crossover point they just go to waste and you won't make use of the full 24. A good selection would look something like this:
Lvt 1200,1600,2000,2400,2600,2800,3000,3200,3400,3600, 3800,4000
Hvt 4200,4400,4600,4800,5000,5200,5400,5600,5800,6000, 6200,6400
If you have some A/F problems at the crossover point you may need to adjust those settings. I don't think the VAFC-II will interpolate between the Hvt and Lvt maps.
Notice I have listed settings as low as 1200rpm, this isn't really usefull to everyone but those with larger MAF sensors or larger injectors can make use of the low rpm/low throttle settings to keep the ECU fuel trims in check (they really need to be as close to zero as possible).
As for the wiring setup, keep in mind that the VAFC-II only has settings for MAP sensors, but it still needs to be wired to your vehicles MAF sensor. And for display purposes I generally use the setting of +15psi, which does not give by any means an accurate display of air mass flow or MAF voltage, it does somewhat put the MAF output into some discernible perspective. It's also cool to show off to your friends, and those who think you have forced induction anyway.
I realize there is still much left out here but I'll try to answer the questions as they arise. I don't have a VAFC-II to look at, so I am having to do this from memory.
The reasoning for getting the V over the S really has nothing to do with it's 'vtec control' or in our case 'rpm switch'. That part isn't a direct wire setup anyway. And it certainly would have nothing to do with attempting to control the VTCs on the VQ35, as some mistakenly suspect.
It's really all about the NE points for setting up the fuel corrections. The SAFC-II has a twelve point by two point map (12x2) which means you can setup 12 rpm points throughout the rev range and 2 throttle points for correction. Anything in between your specified RPM and throttle points is interpolated . The SAFC-II can also be manually switched to a second data file or map to be used with Nitrous or some other more or less aggressive tuning parameters you might need.
The VAFC-II essentially uses both of these 12x2 maps together, effectively making it a 24x2. But it has to be triggered to select between these two maps by a Hvt and Lvt setting (12x2 high vtec, 12x2 low vtec).
Now for the example setups:
So for most of these cars that can only rev to 6500 or 6600, we would set the Lvt to Hvt setting at 4200rpm and the Hvt to Lvt at 4100 (for some reason it wont let you make them the same). Doing this means that the VAFC-II will switch over from one 12 point map to the other 12 point map at 4200rpm. Now you'll need to setup the Lvt NE (RPM) points, obviously you'll want to end the Lvt points at or before 4200rpm because that is where you just set the crossover. If you set Lvt points past your crossover point they just go to waste and you won't make use of the full 24. A good selection would look something like this:
Lvt 1200,1600,2000,2400,2600,2800,3000,3200,3400,3600, 3800,4000
Hvt 4200,4400,4600,4800,5000,5200,5400,5600,5800,6000, 6200,6400
If you have some A/F problems at the crossover point you may need to adjust those settings. I don't think the VAFC-II will interpolate between the Hvt and Lvt maps.
Notice I have listed settings as low as 1200rpm, this isn't really usefull to everyone but those with larger MAF sensors or larger injectors can make use of the low rpm/low throttle settings to keep the ECU fuel trims in check (they really need to be as close to zero as possible).
As for the wiring setup, keep in mind that the VAFC-II only has settings for MAP sensors, but it still needs to be wired to your vehicles MAF sensor. And for display purposes I generally use the setting of +15psi, which does not give by any means an accurate display of air mass flow or MAF voltage, it does somewhat put the MAF output into some discernible perspective. It's also cool to show off to your friends, and those who think you have forced induction anyway.
I realize there is still much left out here but I'll try to answer the questions as they arise. I don't have a VAFC-II to look at, so I am having to do this from memory.
03-30-2010, 05:54 PM
#5
Thanks for the info, Unklejoe. 
I never thought about the resistance created by grounding to the body versus the ECU grounds. Not something I want considering I'm going to be messing with one of the most vital parts of my car.
For now, I'm going to get a dyno tune. I'm getting an LM-1 wideband down the road, so I'll be able to tune my car from then on. I've just got other things to blow my money on right now.
Like getting a decent suspension setup. I'm sick of riding everywhere on my bump stops.
I never thought about the resistance created by grounding to the body versus the ECU grounds. Not something I want considering I'm going to be messing with one of the most vital parts of my car.
For now, I'm going to get a dyno tune. I'm getting an LM-1 wideband down the road, so I'll be able to tune my car from then on. I've just got other things to blow my money on right now.
Like getting a decent suspension setup. I'm sick of riding everywhere on my bump stops.
03-30-2010, 06:05 PM
#6
Yeah, some people ground to the chassis and have no problems, but the "right" way is to connect it to the same ground as the ECU.
And I actually have the Innovate LC-1, which I got for like $190 on eBay. The only issue is that there is no cheap way to get the RPM's to feed into my laptop. The AFR's graphs that the software gives you are in respect to time rather than RPM's.
I worked around it by using a video camera and taping my VAFC-II and wideband gauge during some WOT runs and making my own AFR graphs in Excel. LOL pita
I kind of wish I would have gotten a dyno tune, as I don't have anything else that I really want to do to the motor, but I get some feeling of accomplishment when I do things myself.
And I actually have the Innovate LC-1, which I got for like $190 on eBay. The only issue is that there is no cheap way to get the RPM's to feed into my laptop. The AFR's graphs that the software gives you are in respect to time rather than RPM's.
I worked around it by using a video camera and taping my VAFC-II and wideband gauge during some WOT runs and making my own AFR graphs in Excel. LOL pita
I kind of wish I would have gotten a dyno tune, as I don't have anything else that I really want to do to the motor, but I get some feeling of accomplishment when I do things myself.
05-31-2016, 11:51 AM
#7
Yeah, some people ground to the chassis and have no problems, but the "right" way is to connect it to the same ground as the ECU.
And I actually have the Innovate LC-1, which I got for like $190 on eBay. The only issue is that there is no cheap way to get the RPM's to feed into my laptop. The AFR's graphs that the software gives you are in respect to time rather than RPM's.
I worked around it by using a video camera and taping my VAFC-II and wideband gauge during some WOT runs and making my own AFR graphs in Excel. LOL pita
I kind of wish I would have gotten a dyno tune, as I don't have anything else that I really want to do to the motor, but I get some feeling of accomplishment when I do things myself.
And I actually have the Innovate LC-1, which I got for like $190 on eBay. The only issue is that there is no cheap way to get the RPM's to feed into my laptop. The AFR's graphs that the software gives you are in respect to time rather than RPM's.
I worked around it by using a video camera and taping my VAFC-II and wideband gauge during some WOT runs and making my own AFR graphs in Excel. LOL pita
I kind of wish I would have gotten a dyno tune, as I don't have anything else that I really want to do to the motor, but I get some feeling of accomplishment when I do things myself.
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