First off is I would like to state that I am hoping this discussion will lead to an agreed method for tuning using WBO2 sensors.

I think a little background history will help. If you look at my setup I have a 327 motor with AFR 195 heads, 52MM TB, LT1 intake and 24lb/hr injectors out of a LT1 motor. I also have just started concentrating heavily on PE and AE tuning with an Innovate LC-1 hooked into a $8d with a WBO2 hac. I don't have to worry about emissions, have no CATs, AIR, EGR, etc. Before anybody states "Go Larger Injector" I want to get my tuning down first before I decide I need a larger injector as most of my datalogging is below 5k and I have not maxed out my DC's yet. For PE tuning there are 2 methods.

1. Tune your PE tables to get what you want. The PE tables do not match your desired AFR. Pros are quick and fairly easy to tune using this method. Cons does not follow your desired AFR's.
2. The second method use the AFR tuner to set your desired AFR then adjust your VE tables to match so that the AFR basically matches the Commanded AFR. Cons are that can be tedious to tune your VE tables. Pros your upper VE tables get tuned properly.

I have adopted the second method after starting work on the first method which increased my PE 30% above what it originally was in the upper RPM regions since it seems to make much more sense to me:

1. Select a desired AFR -say 12.2 initially to be safe.
2. Set your PE tables to be the desired AFR across the board.
3. Tune your VE tables so that your desired AFR's follow your commanded AFR's.
4. Adjust you AE tables if needed to smooth out the tip in to PE.
5. Adjust your commanded AFR's to find the sweet spot. Since your VE tables are in line and AFR follows your commanded AFR now your sweet spot should now be fairly easy to find.

Now the VE table adjustment process:

1. Datalogs that have a commanded AFR of 14.73 - closed loop tune your VE tables as normal.
2. Commanded AFR tables lower than 14.73 with warm engine is considered PE mainly looking at WOT blasts with kpa above 90 and TPS between 90-100% -mainly 100%. For me Commanded AFR is known to be 12.2 so I adjust my tables to match those from 90-100kPa.
3. Try to smooth out the transition areas -say 80kPa up depending you datalog tuning in step 1.

Using the method above with my setup has changed my VE tables in the upper kPa regions dramatically. I am running at 90% VE from idle to 100% by 3600RPM. My AFR's are following fairly close in some of the lower RPM areas but I run into about a 13.2 AFR where my VE tables are maxed out even though my duty cycles are not maxed out. Now for the Questions:

1. Has anybody figured out a way to adjust Injector Constants based on Duty Cycles and VE tables?
2. For WBO2 logging what is the proper way to datalog, settings, etc?
3. How would a incorrect IMAT table affect this other than possibly a variance to AFR if the MAT temps vary, the IMAT table is off, and VE tuning was done at a different temp than currently running?

There is more to come but I don't want to be too long in the first post of the thread.

 

I have a question regarding this method - how do you KNOW the VE tables are good here? I mean, I would rather have a "false" commanded AFR, than a lean upper VE table..

Granted, if you're at 5000+rpm, you probably are in PE, and I don't know the circumstances where you would be at a high rpm and not be in PE, or decelerating (i.e. doesn't matter if it's lean)..

 

That is what you are doing. I suggest reading the AFR Tuner post.
https://www.thirdgen.org/techbb2/sho...light=afrtuner
When you are in the upper VE tables unless you turn off PE you will never get there using normal tuning methods. Second part is the PE calculated based on the VE table. Get that right and your commanded AFR follows your desired AFR.

Now onto my first question. I have LT1 injectors rated at 24lbs. I used the injector constant from a EE LT1 bin that is 24.9. I am maxed out on my VE table. If I look at a DA2 table (92-93 batch LT1 code) it uses a injector constant of 23.8. So I adjust the constant down to 23.8 and scale my tables about the 5% change. How do I know my constant is right especially short of flow testing an injector. I have no confidence as to what they are rated at. Is it 24 at 39.6 or 24 at 43.5? I don't just want to blindly set the injector rate. Currently at 2900RPM and WOT my commanded AFR is 12.2 but my measured AFR is about 13. My VE table is already at 96% and my BPW is 8.8mS. Is there a VE % and BPW rate to shoot for here as a rule of thumb or do I just scale my tables and injector constant by 1.2 and start all over hoping I got it right?

 

What I mean is, once the calculated and actual AFR matches up in PE, what makes the VE correct? Calculated VE never matches up to reality... Otherwise we could just tune our VE tables with some math... Or, stated vise versa - we'd just have to tune our VE tables, and set all the commanded PE AFR's to 12.8:1...

with respect to the injector constant, it doesn't need to match up to actual. You can run 50lb injectors with a 10lb constant with no problem. However, changing that constant affects other things, not just shifting the VE table up and down, but AE, etc.

 

The VE doesn't have to be the actual VE, but it should be set to deliver 14.7:1 if running closed loop. A low injector constant can help lower the table value of the VE table allowing you to have control over it. It doesn't matter what the actual Volumetric Efficiency is, as long as the engine gets the right PW in all cases (or as many cases as that are normally attainable).
I agree in the setting the PE to a certain commanded AFR, and then tinkering with the VE to get the AFR to match. Let's say you are doing a full throttle blast, and lift just enough to turn off PE. I sure wouldn't want it to be 18:1 and 60-80kPa for that moment before it shifts (or for the manual tranny guys).

 

Can we make the assumption the stock calibration is 100% tuned from the factory, perhaps a little rich to compensate for individual engine variations?

Here's what the stock PE table looks like ($8D):
0 12
400 12
800 12
1200 14.3
1600 14.3
2000 12.2
2400 14.6
2800 14.6
3200 15.4
3600 14.3
4000 15.2
4400 14.3
4800 13.2
5200 13.2
5600 13.2
6000 13.2
6400 13.2

There's no way it hits 13.2:1 at everything above 4800... which brings me back to my point... With the VE table PERFECT, i.e. 14.7:1 everywhere... The commanded (calculated) AFR won't match up with the actual AFR as read by a wideband. And if it does, either a) you're lucky or b) the VE table isn't tuned for 14.7:1. There's always some error in calculations, that's a given. Sorry, didn't mean to hijack...

 

That's not the whole PE table. That's just the RPM multiplier of the PE table. You're missing the PE vs Coolant Temperature table.

 

That is what this post is about. In the past I may have agreed with you. Tuning to a PE table is still calculating based on your VE table that it hits. I don't know what GM tuned to neither do you unless you have a stock car with a stock chip and have fully tested this. My car is not even close. If you tune using the PE and it says 13.2 and you are running 12.5 you are lying to the motor using the PE table. Again the PE calculations are based on the VE table. The VE table is tuned to 14.7 as stated in CL. Has anyone turned off their PE and tuned their VE at 100kPa? I don't think so. PE for a stock bin is 50-70% of the TPS depending on the RPM. Others have proven that when you get the VE tables in line it is pretty accurate.

Setting an Injector Constant to an extreme is again a lie. So is changing the motor size. If I decide to run my motor to 7k my injector I'm sure is way small. If I only go to 5k it may be sufficient. Cam, intake, etc. all limit what the motor can do. Maybe all I need to do is change the constant and take it as such or do I take an guess at what it should be? For me I want to try to get it right.

BTW Not to **** anybody off but would you say the same thing about a 2006 Z06 Vette? I think that you do not give GM enough credit. Your statement sounds like you know more than GM did at the time. If I was a betting man I would go with GM.

 

No, but here's what I was thinking. Turn off PE. Tune the entire VE tables for something "safe", like 12.8:1. Then you have the entire VE table mapped, and have the shape of the curve. Then just shift the whole table for the difference between 14.7 and 12.8 - the 0.13 lambda difference.

 

To keep it simple
The code calc's a PE value and a VE value
Then adds them.
So if you make PE zero, you may be limited in how low you can get the afr

 

From the p4 document,
It's not an addition, it's a multiplier. It changes the inverse A/F term into the value found in the A/F PE table

BPW = BPC * MAPP * T' * A/F' * VE * F33C * BLM * DFCO * DE * CLT

In any case, you would probably have to change the BPC constant to shift the VE tables up by that 13%, I doubt the VE tables would have that much adjustment left. The good news is that makes adjustment relatively easy. When you're done, just change that value back to "stock" for a 14.7:1 AFR across the table.

 

Good now I think we are getting somewhere. I've been going over the Tuning article. The article slowly increases the PE Vs TPS tables -first 85%, then 90%, then say 95-99% to slowly get those tables inline. Per SAUJP and Z69's patch I would then just set the 95-100kPa tables to be the same values. The next step would be to turn on the PE and see if the AFR matches the commanded AFR. If my Injector constant is off I would assume it should be scaled accordingly. I really think that I should not be concerned with where the VE values are unless I am at 100% (which I am) and my AFR's match my commanded AFR's(which they do not). Once my Injector Constants are close everything should fall in line. Now can this be made into a calculated guess when changing the injector constant?

 

seems to me that if you are achieving 100% VE, according to that formula above, the percent change should follow. so if you wanted the VE to drop say 15%, you can bump up the injector constant 15%, and see what happens. You should be able to burn a couple of iterations, and see how the percentage tracks. try like, 5, 10, 15%. See if the resultant BLM's change the like amount.

I beleive that LT1 injectors flow more like 25.5 or so at 43PSI, the two sets I had cleaned by Rich from Cruzin Performance average there.

 

To keep it simple.....

The P4 doc is based on the $58 code. Not $8D which is what we are discussing
Not everything is multiplied as that formula lists.
If I had said they were mult. and then said PE= zero it would have caused confusion.

 

Back to Injector constant. There is thread that talks about it. It says up the injector by 1.2 and divide the table by 1.2 to scale it down to 80%. I believe that it should say the injector size needs to be decreased by 1.2 so that it stays open longer. If the PE is a straight multiplication or addition of the basic calculated BPW then it really does not matter. I already did a test by changing the constant to 24lb instead of 24.8. I also have a LC-1 which leads me to my second question on WBO2 tuning. Until that time I had the Innovate response speed set to Instant in the advanced setup window. The WBO2 sensors are much faster responding than a NB. Somebody asked Innovate what it should be set to for a 10MHz datalog setting. The response was 1/12sec. Besides the injector change constant that was the only change to the bin. On my next datalog my AFR values jumped between 10-20. I thought I went through and adjusted the tables but I guess I did not. At that point I went back to the 24.9 setting and to a Instant response time on the Innovate. My logging was more linear. Anybody else try the response speed setting without any other variables set for a datalog?

 

Back to Injector constant. There is thread that talks about it. It says up the injector by 1.2 and divide the table by 1.2 to scale it down to 80%. I believe that it should say the injector size needs to be decreased by 1.2 so that it stays open longer. If the PE is a straight multiplication or addition of the basic calculated BPW then it really does not matter. I already did a test by changing the constant to 24lb instead of 24.8. I also have a LC-1 which leads me to my second question on WBO2 tuning. Until that time I had the Innovate response speed set to Instant in the advanced setup window. The WBO2 sensors are much faster responding than a NB. Somebody asked Innovate what it should be set to for a 10MHz datalog setting. The response was 1/12sec. Besides the injector change constant that was the only change to the bin. On my next datalog my AFR values jumped between 10-20. I thought I went through and adjusted the tables but I guess I did not. At that point I went back to the 24.9 setting and to a Instant response time on the Innovate. My logging was more linear. Anybody else try the response speed setting without any other variables set for a datalog?

 

One thing you are forgetting is the Injector Bias. Basically, its the advance for the injector opening. Increasing injector bias will give you a "truer" injector PW particularly inn the upper rpm range. With a more accurate representation of the PW, you'll find your commanded AFR will more closely approximate your actual. And basically, I tune WOT first, then the rest of the VE table. First of all I am interested in making certain I have enough head room on the injector PW/DC%. I'll adjust IB and Fuel Pressure to get to an adequate Duty Cycle at WOT-PE, then tune part throttle.

 

There is no injector bias in the $8d defintion unless it is named something else. I do like the idea about setting your WOT first. I think I found out what I was looking for now to try to tie it together. There is some discussion on the IMAT also:

https://www.thirdgen.org/techbb2/sho...pw+calculation

 

There is a low PW offset in 8D. The table goes to 3.9ms.
Not sure when or if the code uses it.

 

69,

Check to see if it isn't a table, not a constant like the 7747. I know the 8625 had it. Shows up as an injector bias vs volts.

 

Yes there is a volts table that adds pw in usec.
And the low pw offset for idle/low rpm use.
But all the explainations I've seen have been for a 747 setup.
Most don't read everything.
Would you care to explain Dominic?

 

The volts table is just for power compensation to ensure the rate of opening time is consistent for the calcs. I don't see anything like a specific bias that could be applied except for the Baro adjustment to the VE calc. That was explained to be for when the mufflers/cat get blown out over time and the exhaust begins to flow better, also for different altitude that causes the same effect. Possibly took the BLMs out to left field so GM put in as a correction factor.

I'm interested to know what the TBI code has this bias for as well. Sounds like it may be needed on larger injectors with high mass or long open/close times. May not be needed on smaller sizes and that's why we don't see it used.
TIA

 

Well after digesting the thread for a while my conclusion is:
1. Scale the tables by adjusting your Injector constant down until you are satisified with the tables regardless of what the injector size really is.
2. You should not adjust your engine size because that changes your GMS AIR calculation.
This also enforces the tuning of the VE tables and how important it is to get it right:
BPW = GMS AIR / (AFR * Injector Flow)
It also enforces getting the engine size correct:
GMS of Air / CYL = ((MAP - EGR) * INV MAT) * VE and
INV MAT = CYL VOL/((MAT + 233) * 128) where:
” MAT is the MAT counts as retrieved from the “MAT Compensation Counts vs. MAT table
Next more investigation on the INV MAT just to make sure.....

 

The TBI code has a single Injector Bias constant, not a table that compensates for voltage levels. RBob is the one who clued me in on the use of the IB. Basically, think of it in the same manner as Spark Advance. The Injector takes a certain amount of time to open. The bigger the injector, the more time to get to required PW. So by increasing the IB, you effectively increase the PW. Increase the IB in that table for the 14v setting. You'll notice your AFR getting richer. That's because your getting more fuel even though you haven't increased the VE. I'm currently using the EBL and RBob has this same table in his code. In my 7747 code, I had only one value which was set at 671msec not the 396 you see in most stock bins. Particularly with bigger injectors and higher FP, IB becomes a great tuning tool. You'll see your commanded and observed more closely tracking each other.
BTW, I disagree on playing with the Injector Constant. You should set it to the calc based on Injector size and FP and tune for that.

 

BTW, I disagree on playing with the Injector Constant. You should set it to the calc based on Injector size and FP and tune for that.

Well by 3600RPM I am at 100%VE. My calculated Injector Constant should be 24.16 and it is set to 24.9 which was the factory setting from a bin that used the injectors. That is based on 24lb/hr at 43.5PSI. Even at my lower RPM's my AFR is already over 13 with a VE of 94% and a commanded AFR of 12.2. Of course I can go to a larger injector but I have not proven that I need to yet. Back to my point about the injectors anyway I really don't know what they are rated at exactly short of flow testing them. The original question is there a way to know if my constant is right ro do I need to be concerned about.

 

69 Ghost,

What you're telling me is that you need more fuel. Bump the FP. And/OR try increasing the Injector Bias at 14v in your table.
Read my post again. Increase the FP for WOT operation, then tune Part Throttle from there. There is an equation for calculating the new IC based on original injector capacity and the increase in FP. Make sure the Duty Cycle is in the < 85% at WOT. Then you know you have enough FP. I suspect your DC% at WOT is 100%+ at this point and injectors are static.

 

he has enough fuel. he doesn't have enough "table". He said his injector duty is fine, but he has maxed out the VE table(s).

 

"I am running at 90% VE from idle to 100% by 3600RPM."

He's not out of fuel?? He doesn't have "enough table"????

 

Yes ryan got it. I bought the injectors used off a 96 LT1. If you look at any GM injector tell me where to find an official page as to their ratings based on the part number -it does not exist. I took the constant off of a LT1 bin that the injectors were on. LT1's are supposed to be very sensitive to pressure changes so I opted not to get an adjustable regulator and all LT cars are supposed to have the same pressure which happens to be the standard GM 44.1. The AIR is calculated to the engine size, based on cylinder size and 'filtered VE' which is just the multiplier of how much the cylinder is filled. BPW is then calculated based on that calculation for the AFR -just a multiple. It goes something like this. If I have tuned tables for a set constant I can scale that constant and VE tables accordingly and should end up with the same result -the same BPW. From how I understand it this is the last calculation to get the BPW.

 

Yes, he's not maxing out his injectors, he's maxing out the table adjustment.

What you need to do is adjust the base pulse constant (BPC). I don't know how that's done on 8D, but it appears to be through the injector constant, since I can't find a BPC vs EGR table...

 

I was always under the impression that the 730 suffers from the same 255gm/sec limitation as 165, though indirectly. I too have my VE maxed at 4400 and 4800, i just lowered the commanded at 4400 by .5 and 4800 by .3 to get ~12.8 across the board.

 

PP I've seen you lurking around here and there but not for a while. The latest is I had one data run that I had adjusted my Injector constants down to 24.15 and my datalogs started swinging much more than my other runs so I went back to the original Injector constant of 24.9. I have a new burn that I did quite a bit of changes to and hope my data log will put me in line:

1 Changed Injector constant to 24.15 from 24.9
2. Changed the IMAT table to the relocated MAT in the intake.
3. Changed my PE to not kick in until 92.5%.

I figure I am somewhat safe as my VE tables in the upper regions are at least 90% so I hope to see what my BLM's look like. My datalog with the lower constant had richer PE AFR's. The next datalog should tell me if I am moving in the right direction. The reason I didn't want to increase my PE % is that my original tune was pretty high that is when I went to the VE tuning method...

 

BTW. Z69 fix a PW limit in SAUJP for large cube motors.