Where do I find a basic chart or something to get a relative air fuel mixture ratio for inputting into my EFI system. I had a smaller engine, 396 and was ok running 14:1 @ idle and close to 12.5:1 @ WOT and everything worked fine.

Now, I have a 496 and not sure if the same numbers will work for the new setup.

I changed from 62# injectors to 80# injectors.

Anything information will help and I can provide any information needed as I know all of the components.

Thanks in advance,

Did you enter the new injector sizes into the GUI? A/F will only be as accurate as the info the ECU has on the system. That is a big injector change.

Ron

What's the cam specs?

Ron,

My setup only has (4) injectors. It's a big step, but it's a big different in motors.

Cam specs:
Comp Cams XM284HR

Cam details: Hydraulic Roller Comp cams XM284HR
RPM range: 2200 to 5800
Lobe Separation: 112°
Intake Centerline: 110°
Duration: 284 intake / 290 exhaust
Duration @ .050: 230 intake / 236 exhaust
Valve lift: .547 / .547

Maybe I missed it, what injection system are you using?

Devin

No you didn't miss it. I didn't post it.

I'm running the Powerjection I system by Retrotek speed. I know it's not the best on the market, but I was after the carburetor look. I purchased the system about 5 years ago.

I had the system running great with the 396 and wasn't too far off of from the default settings. Even then, I didn't understand everything and didn't truly know what I was tuning. I just drove down the road alot and changed values as I felt they needed to be changed.

There is another table that fine details can be changed, but I don't think I'm that advanced and a bit afraid to touch it. I can post if someone wants to see what it looks like. Here's a link to the website for the system itself. Keep in mind that I have the Powerjection I system and they're on the Powerjection III system as mine it a few years old now. http://www.retrotekspeed.com/index.php

Here's a few screen shots:

Here's the screen where I can change the Air / Fuel Mixture Ratio
http://inlinethumb29.webshots.com/48604/2951851770052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2951851770052249461IydEan)

Here's a screen to see the spark advance
http://inlinethumb25.webshots.com/49944/2888518790052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2888518790052249461SfSOZG)

A screen shot of the VE table (Volumetric Effeciency)
http://inlinethumb55.webshots.com/48054/2463830260052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2463830260052249461YZvCKn)

And here's a live shot with the vehicle running @ idle
http://inlinethumb32.webshots.com/32479/2847317310052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2847317310052249461ECxWQO)

As far as just the A/F's, those should still be good.

I see you have a closed loop light; are you running closed loop?

Have you seen the pressure to the injectors change? (may happen with larger injectors, pump may not keep up)

I looked at the installation manual and there is a place to change the flow rate of the injector in the software. It is shown on page 9 under the fuel wizard.

Ron

Ron,

I do run the closed loop. The regulator is set around 44-45 psi. I do see a fluctuation in the pump pressures between like 42 psi at low point and high side of sometimes 49 psi. But of course its switching so quick that I figured it was just trying to keep it's balance.


Doug,
I mostly just cruise around in the car. Should I go a little leaner on the mixture?

Ron,

I do run the closed loop. The regulator is set around 44-45 psi. I do see a fluctuation in the pump pressures between like 42 psi at low point and high side of sometimes 49 psi. But of course its switching so quick that I figured it was just trying to keep it's balance.


Doug,
I mostly just cruise around in the car. Should I go a little leaner on the mixture?

I would believe that just changing the injector size under the fuel wizard you should not have to change the A/F settings at all.

You need to make sure that your Lambda sensor is good too..

Ron

The A/F ratio is mostly a function of how the engine works rather than engine size. Thus the same ratios that work on a 396 get you pretty darn close on any Chevy engine.

Also note that the A/F ratio is part of closed loop operation generally and requires a good wide band O2 sensor for feedback. With a good sensor and feedback, a good EFI control system will adjust the injector pulse to achieve the specified AFR.

In contrast you show a "V/E" table which is a raw input that drives injector pulse based on a concept of how well the engine is pumping air, i.e. Volumetric Efficiency. This gets into doing math with RPM and manifold pressure to calculate how much air the engine is consuming and then calculating how long the injectors need to be ON to deliver a matching amount of fuel. This is the base table that drives operation... the AFR table just tunes and tweaks things on top of the VE table.

Things that invalidate the basic "one size" AFR comment are significant power adders like nitrous, superchargers, or turbochargers. These may require more fuel to cool the engine and prevent detonation.

Likewise you may need a different AFR at idle depending on cam parameters. But this is an area where you tune to taste anyways. Note also that as overlap is increased on a cam the accurracy of wide band O2 feedback decreases.

On an older system I would start by verifying you really do have a *wide* band O2 rather than the older more common narrow band. The narrow band were very good at reading the stoichiometric 14.7 AFR and not very good at reading anything else.

Steve,

Thanks for the information. I can verify that it is a wideband O2 sensor. What I'm curious about is how the VE table works. The control box has a "Smart Learning" technology that helps the control system to try to figure out my driving habits and what the engine really likes.

I will agree with you that I though the injector size really didn't matter as the O2 sensor is looking for whatever magical number I plug into the AFR value box for whatever RPM I'm searching for.

If you notice above, on the AFR screen, I had the idle AFR @ 13.5. Notice on the live shot that the AFR is at 13.3. It does well at achieving whatever value I input. The regulator is set @45 psi and you can see also on the live shot that it's @ 44.7 psi.

It also appears that the Spark Advance actually knows/verifies what I see with the timing light. It's a pretty neat system, but more clarification on where the AFR should really be is what I don't understand especially when you reference this against the camshaft.


Ron,
I'm not sure of what a Lambda sensor really is. I didn't see this in any of the literature.

One thing that is pretty cool about the system is the "Acceleration Enrichment" slider at the bottom left of the screen. It reads in the manual that it works like an accelerator pump on a carb. You can really tell that it's shooting more fuel upon acceleration. So that also needs to be taken into account.

The car runs good and idles great. I'm just trying to get a handle on what I should really have as values and what it really all means.

Steve,

Thanks for the information. I can verify that it is a wideband O2 sensor. What I'm curious about is how the VE table works. The control box has a "Smart Learning" technology that helps the control system to try to figure out my driving habits and what the engine really likes.

I will agree with you that I though the injector size really didn't matter as the O2 sensor is looking for whatever magical number I plug into the AFR value box for whatever RPM I'm searching for.

If you notice above, on the AFR screen, I had the idle AFR @ 13.5. Notice on the live shot that the AFR is at 13.3. It does well at achieving whatever value I input. The regulator is set @45 psi and you can see also on the live shot that it's @ 44.7 psi.

It also appears that the Spark Advance actually knows/verifies what I see with the timing light. It's a pretty neat system, but more clarification on where the AFR should really be is what I don't understand especially when you reference this against the camshaft.


Ron,
I'm not sure of what a Lambda sensor really is. I didn't see this in any of the literature.

One thing that is pretty cool about the system is the "Acceleration Enrichment" slider at the bottom left of the screen. It reads in the manual that it works like an accelerator pump on a carb. You can really tell that it's shooting more fuel upon acceleration. So that also needs to be taken into account.

The car runs good and idles great. I'm just trying to get a handle on what I should really have as values and what it really all means.

Sorry, the Lambda sensor is the A/F sensor. You indicate that it is regulating A/F so the sensor must be good.

Most of the control systems have clamps on the loop so that the system can't get too far from the set point this keeps the error term from getting too large and "railing" in such a way that the regulator becomes unstable.

The size of the injector is important as is shown here:

http://www.bgsoflex.com/auto.html

If you make your injectors too small they will work fine at low loads/RPM but not at high loads/RPM (VE). If you make them too large the idle may not be all that great (as you come up to their minimum operational pulse width) and the control range may be diminished depending on the number of bits in the control system, e.g. one more bit of PWM gives too much fuel, so the system pulls back the one bit but that is too little fuel.

Did you change the injector size in the software?

If you did it should be the same as it was before unless your control steps are too big as described above.

Ron

I have everything pretty much set at 14:1, and then it tapers off to 12.5:1 at WOT. You dont have to go crazy hear, 14:1 is a pretty good setting for idle and cruise.

Ron,

From what I can tell, there is no way to change the injector size within the program. I will however contact the manufacturer to see if it is possible. Thanks for the website. I think I need to study up a little more on this VE (Volumetric Effeciency). I'll be off at work for 2 weeks and will cram as much information as I can and try to pick the brains of the manufacturer as much as I can. The program will be with me to explore a little more during my time at work, but I will still ask questions to try to understand more about it.

Hopefully after returning home, I can get it tuned in pretty close and have the vehicle dynoed.


Vince,
This same system with my 396 was tuned just the way you said it. I had idle settings and most of the low RPM settings @ 14:1 and at WOT had it down to 12.5:1. I'll try playing around with it and see what I can do.

Ron,

From what I can tell, there is no way to change the injector size within the program. I will however contact the manufacturer to see if it is possible. Thanks for the website. I think I need to study up a little more on this VE (Volumetric Effeciency). I'll be off at work for 2 weeks and will cram as much information as I can and try to pick the brains of the manufacturer as much as I can. The program will be with me to explore a little more during my time at work, but I will still ask questions to try to understand more about it.

Hopefully after returning home, I can get it tuned in pretty close and have the vehicle dynoed.


Vince,
This same system with my 396 was tuned just the way you said it. I had idle settings and most of the low RPM settings @ 14:1 and at WOT had it down to 12.5:1. I'll try playing around with it and see what I can do.

Excellent! Please post what you find out.

Ron

I called the manufacturer and he just opened up even more options that are hidden within the system for people who don't know much not to touch.

There is an area to change the injector size. There's an area to change the complete fuel mapping, accel, decel, ignition, power enrich, closed loop, idle, iat, baro, afr, cranking, cold engine.

I'm a bit overwhelmed at all of the options that I can use to destroy something. There are numbers in all of the boxes and if someone is interested in seeing what it's showing, I can capture a screen shot and post the info. Of all those options listed above, just let me know which screen to capture.

You pretty much hit on it: the AFR is used mostly as a self-learning and auto-tune function. The AFRs you ran before will be just fine now.

With a AFR sensor (lambda or wide band O2 or just O2) the system will always self-adjust a bit for conditions. Ideally you want that correction to be as small as possible. That is where the auto-tune features come in. Most systems have some "button" you push that takes recent data logged while you drive and make corrections to the V/E table to get it closer to ideal. If the V/E table were perfect, and environmental conditions constant, you would need zero correction from the AFR control system.

Yes there are lots of parameters possible to tweak in an EFI system :yes: This is a big part of why they are so cool B)

You bumped your injector size up by 30% so you get 1.3x the fuel per count on the injector open time. At idle you cannot reduce the count below a minimum value which usually sets the upper end of what you can run for injectors (unless you start getting exotic with multiple injectors per cylinder). Sometimes you can find a meter or logged value in the software for your injector pulse duration or width. That can give you an idea of how close to the bottom edge you are. Same thing for the high end where it turns into a "duty cycle" and I think I have read that 80% on is about the upper limit.

You bumped your injector size up by 30% so you get 1.3x the fuel per count on the injector open time. At idle you cannot reduce the count below a minimum value which usually sets the upper end of what you can run for injectors (unless you start getting exotic with multiple injectors per cylinder). Sometimes you can find a meter or logged value in the software for your injector pulse duration or width. That can give you an idea of how close to the bottom edge you are. Same thing for the high end where it turns into a "duty cycle" and I think I have read that 80% on is about the upper limit.

Exactly! Yes, 80 to 85% is maximum for the Duty cycle.

Now that you have access to the proper screens, I would just change the injector size and retest. If you still have issues I believe you have a datalog function. Set it for a half hour and plot Duty factor and A/F ratio after warm up. I'll bet you'll be pretty much there.

Ron

I do infact have a logging option on the system. It'll be 2 weeks before I get back home to try the new properties. I will monitor what you guys mentioned and see what happens. I don't know exactly what I'll see on the logging information, but I'm sure there should be something there useful. In the meantime, I'm going to do a screen shot of the different options I mentioned. If anyone here has time to overlook the different screens to see if there is something that shouldn't be there or something that should be changed. I'm assuming that this is all default information.

Sorry to overwhelm you guys also, but here are the screens I can see to change I guess whatever I'd like to:

Here's the 1st screen from the setup menu:
http://inlinethumb63.webshots.com/46846/2799520570052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2799520570052249461LxgUvs)

Then, here's the Base Fuel Map Editor, where I was able to change the injector size in the upper right corner: If you ask me where all those numbers came from, I simply selected from a list of profiles that were currently saved in a database that was closest to my application.
http://inlinethumb62.webshots.com/23037/2703149750052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2703149750052249461wrtVTS)

Then, if you click in a certain hidden secret spot on the page shown above, other options come up and they're shown all below with information already filled out:
http://inlinethumb64.webshots.com/49215/2293925760052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2293925760052249461qlRNpm)

http://inlinethumb30.webshots.com/47645/2795183340052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2795183340052249461BqFcBy)

http://inlinethumb55.webshots.com/49526/2155248520052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2155248520052249461lzyOaK)

http://inlinethumb52.webshots.com/47027/2792730550052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2792730550052249461lrMSuK)

http://inlinethumb20.webshots.com/46419/2397615150052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2397615150052249461ejTyBa)

http://inlinethumb44.webshots.com/46827/2449792910052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2449792910052249461SjuIlk)

http://inlinethumb05.webshots.com/4356/2784339910052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2784339910052249461vJoxIK)

http://inlinethumb18.webshots.com/48977/2383215720052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2383215720052249461edIEOM)

http://inlinethumb01.webshots.com/24640/2021771830052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2021771830052249461KADwnq)

http://inlinethumb28.webshots.com/50075/2828282930052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2828282930052249461kcndUc)

http://inlinethumb58.webshots.com/1017/2747109660052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2747109660052249461UqsXBX)

http://inlinethumb53.webshots.com/43060/2635088820052249461S600x600Q85.jpg (http://home-and-garden.webshots.com/photo/2635088820052249461QIsYIR)

Once again, sorry to overwhelm you, but here's all of the editable information available to me.

Do you have a copy of, or can you download from your existing ECU your original configuration file? Or is this it? For a 66 Caprice?

Ron

The software is similar to any other EFI system. You download a profile that is close to what you have and tweek it from there. The original configuration that I used has been wiped off for the newer configuration.

The profile that I'm using now is for a 650tq setup that had (4) 95lb injectors. From that profile, I've made a few changes, mostly to the AFR on the main screeen. Anything else beyond that is default information from the profile, except for the injector size difference that I was able to change.

I've looked at the different profiles that I have downloaded on my computer and they're all the same on the hidden information that I guess people didn't know was there. I'll go through them again just to make sure.

The name of the profile is now named for my application so that I can keep track of it.

One thing to consider here is that even the best wideband O2 sensor cannot accurately report the A/F ratio at idle on an engine with a cam that has moderate to serious overlap. The overlap in the cam introduces fresh O2 into the exhaust stream which tricks the O2 sensor into seeing it as a lean mixture which causes the ECU to introduce more fuel. Even though the WBO2 reports 14:1 at idle, it will be significantly richer as in the 11.5-12:1 range or maybe worse depending on the cam and idle RPM. The best way to set the idle A/F ratio is to set it on the lean side to start then read the plugs to see what the engine likes. HTH

What tom said. WB02 numbers at idle on big cam engines are worthless. If it's showing 14 it might be 12.5. tune the idle to max vac/RPM and fatten it a touch from there.