I have read the post and still having trouble understanding the WOT tuning for my 1991 Z28. Can someone really dumn it down for me? I have messed with injector constant, fans, EGR, VE tables but need to work on the WOT stuff. I have installed a WB 02 and am ready to do some WOT tuning. I have datalogged some runs and it is 14.5 to 16 range at WOT. I just do not get it. I may be missing something so please point it out. Thanks in Advance, BranZ

 

Is this the post you read?

https://www.thirdgen.org/forums/diy-...t-afr-how.html

What do you need help understanding, the whole thing, tuning process, or what?
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You need to get your full VE table in order, tuned to 14.7:1. This means, 14.7:1 at all points in the VE table. You'll need to disable PE to do this (well, maybe, you should be able to use commanded vs actual and work backwards...), but anyhow there should be a write up on that in the stickies. Anyhow, you cannot do WOT tuning (well, PE commanded AFRs) until your VE is correct, as the PE fuel is derived using the VE table.

 

I guess I am getting confused with the assembly code. I have been able at this point to find the constant or table and make the changes. I will print it out and go through it again. I just get confused with the numbers. BranZ

 

Assembly code?

I'm also trying to get up to speed on PROM tuning, and I'm using TunerPro RT and starting to due some logging to see where I'm at.

Correct me if I'm wrong, it appears to me that everything I need to edit to complete a tuning is available to edit in table form in TunerPro. I know in the "old days" before the programs got better you had to work at the assembly level, but aren't those days past us now?

What would be great is if someone could overview how to start from scratch with TunerPro and then go through the various steps and processes of getting an engine to run the best it can in all the various running conditions.

Paul T.

 

Pretty much everything you usually need to edit is defined in TP. Theres no need for assembly to tune. In the old days, you would have been confined to editing the raw data in the tables and reverse engineering the code to figure out what does what.

For tuning, Id recommend a wideband. While its not terribly useful under certain conditions like cold operation or at low speeds with a cam that has overlap, for WOT, it will make your life easier. Basically you hook up your wideband and observe or datalog its output. If your at 2400 RPM and 100 kPa, your desired AFR is 12:1 and you see 14:1 on your WB, then the correction in most cases would be to take the VE at that location and multiply it by (14/12). This will scale the VE up to raise the AFR in that area. After youve hit most of the areas, the rest would be just smoothing the VE table.

 

Dimented, thanks for the informative reply. Hopefully you can stand a few more questions to help me get a better understanding.

On my car and its 16136965-$62 ECM (ok, not a Camaro, its a '91 Caprice L03) I have a Main Fuel Table %VE #1 which goes up to 3200 RPM and a Main Fuel Table %VE Adder, with this second table going up to 6400 RPM.

It appears to me the first step after getting the engine to idle correctly would be to use logging to look at the BLM values for different engine conditions and then use these to correct the table above. I think I understand how to figure the new table value based on the BPM value, ie New Value = Old value * BLM/128

Assuming we had the log BLM values, what's the best way to make the mods to those two tables, ie when do you mod table one versus table 2? Is the New Value calc above only applied to one table or two the values in both tables?

Also how to you handle that fact that table 1 ends at 3200rpm, is that last set of values used for the higher RPMs?

Given we had the tables above now tuned correctly for part throttle closed loop operation, and assuming we have a wide band 02 system to use, how do we now go about tuning the WOT mode, and what tables do we now modify?

Thanks,

Paul T.

 

Much of this is covered in the stickies. As far as table one and table two, they are added together to achieve final fueling, so yes, you need to change both. There is a way around that additional calc for table 2, 3200 and <, but will not confuse you there. You can tune the VE above 3200 so it that case you just deal with table 2. That requires a steady throttle and lock in the gear.

In my case the commanded PE A/F turned out to be very close(WB) since my underlying VE was accurrate. I think many of us set PE at 12.5/1 in .bin to start.

 

I did go thru all the stickies once and maybe not enough "stuck" so I need to do it again, but this table1 and table2 stuff still twists my brain, I just don't understand what was the advantage and intent in implementing it that way.

Can somebody give a basic explanation of why they implemented this 2 table system and how you can use it to the best advantage when doing tuning?

How do you decide when making a change if its best to change table 1 or 2?

Paul T.

 

Example say you have a datalog at 2400 rpms and 50 map showing BLM 142 or adding fuel as in lean. you would multiply both tables 1 at that rpm/map and table 2 at 2400 by 1.11.

GM did it for a good reason? maybe to save space? The resolution is not the best. same on AE tables.

 

Thanks for the help Ronny.

Ok, making that mod based on the BLM val makes sense to me. One thing about it though, since table 2 effects all the final results at 2400 rpm for all MAP values, by changing table 2 now I've just slightly richened up all my 2400 rpm values, correct?

It seems to me that if you know your change is to be very specific to a particular RPM/MAP cell then you would only want to change values in table 1, adding only to table 1's value so the summed new value equals the summed old value times 1.11 .

So it thats true, it appears that the only time to mod table 2 is when you are above the highest RPM setting of table 1.

Is that correct or am I missing something here?

Paul T.

 

Quote:by changing table 2 now I've just slightly richened up all my 2400 rpm values, correct?

Yes.

Now let me throw this out there. This may be confusing. Lets say you incorporate(add) all Table 2 values into table 1 for that 2400 RPM? IOW'S then you deal only with table 1? BUT it was said by others(Grumpy) to leave a value in table 2 of say 5. So that being said one could do same for all table 2 under 3200 rpms. I have not tuned VE in that manner for some time but that is what I did back then. Now I recall one needs to leave a value in at 0 rpms? I forget. And leave 3200 alone if I recall. Is that easier?

 

Dont get too hung up on the adder table. Its there as a ROM/PROM space saving measure. The early TBI ECMs where way short on space and RAM, so they did a lot of stuff like that to make it all fit. The VE table only goes up as far as it has to for normal driving conditions. The VE adder table is there to provide some measure of control over the VE after the engines RPMs ahve exceeded 3200 RPM. Once that happens, the last row of VEs + the VE adder = the total VE. This allows you to reduce the VE to keep the engine from going overly rich at high RPMs. Normally the VE adder table can be left alone below 3200 RPM. The only times youd really need to touch the adder table at lower RPMs is when the main VE starts to zero out.

 

Ok, that makes some sense on why they split the tables.

So lets assume we get the engine running well up to 3200 RPM. Now I'm working above 3200 and at this point I only have table 2 to work with to get the BLM's in shape, adding the last row of table 1 in for the final numbers.

To not mess up the tuning that had been done under 3200, at this point anytime I make a change in table 2 I need to take that amount off the row values in table 1 to not change the original tuning, correct?

Now on to fuel side of WOT tuning, assuming table 1 and 2 are now locked down, TunerPro for my bin is showing me the following 3 tables that appear to control WOT:

Power Enrich Air Fuel Ratio vs. RPM
4800 11.8
3200 10.6
2000 11.3
1200 12.2
400 11.8

and

Open Loop AFR vs. Coolant Temp.
148 12.7
139 12.7
109 12.7 (stays at that val until 56)
...
56 13.6
50 13.6 (after this starts dropping down)
...
-37 8.5

and

Open Loop AFR Vs. Vacuum
0 0.7
10 1.2
20 2.0
30 3.0
40 2.4
50 2.4
60 2.4
70 2.2
80 0.8

There are also three constants:

Idle Open Loop AFR Adder 1.7

P.E. Mode AFR Coolant Temp. Correction 108

P.E. AFR Temp Correction Temp Thresh. 6.67

Can anybody take a shot at how I adjust those tables and constants to tune in WOT, and am I missing any other tables or constants that need to be modified?

Thanks,

Paul T.

 

Quote:To not mess up the tuning that had been done under 3200, at this point anytime I make a change in table 2 I need to take that amount off the row values in table 1 to not change the original tuning, correct?

I will assume you are refering to RPM's in excess of 3200. For instance 3600.
If you get a hit at 3600/60 Map for BLM you only adjust the 3600 in table 2. But you will find it is not all that easy to get upper RPM hits for BLM. also to get upper RPM BLM hits you may need to find a long stretch of highway with a steep grade to hit the higher map BLM. Also I found myself at high speeds trying to do so on interstate. not good. I am uncertain how others get data for high rpm BLM. here a dyno might help($$$).

I think I had the same values in my PE table accross the board 12.5/1. on WB it showed 12.0/1. Sooo my VE table there was fat. This was when I have a 7747 on a diff motor.

Open Loop vs coolant. I guess the is primarily choke off cool engine <160F. I will guess the others are adders.

 

This is the ultimate question for me also. The assembly code stuff threw me off. I know that it is not needed anymore with TunerPro. I just do not see the relationship between the tables. BranZ

 

The best way to learn is with a stock vehicle or a slightly modified vehicle. otherwise it will be a steep learn and frustrating experience. I started with getting my base VE table in line with dozens of datalogs. My car flat out would not run as my stock tune disallowed such. I would say every table needed help.

 

If you tune the 2 VE tables all the way to redline then that should take care of WOT? This is of coarse based on use of a wide band sensor. BranZ

 

BranZ, I believe doing that (using table 2 to tweak WOT) would work for the most part, but keep in mind that table 2 is shared for both operational modes, closed loop and WOT.

So if you use it to optimize the WOT mode, it probably won't be best for closed loop.

On the flip side if you optimize table2 first for closed loop only at higher RPMs and then leave it alone, my best understanding is that you can then use the PE AFR vs. RPM table to dial in the WOT performance without effecting your open loop operation.

Can someone confirm if that is correct?

Paul T.

 

By getting the VE table correct to what the engine wants you'll kill two birds with one stone in that in closed loop it will equal 14.7 and 128 blm. At wot it will equal the AFR in the PE AFR table. Keep in mind that you are in this table anywhere passed the PE enable point (around 30% tps). It's also not safe to run 14.7 at higher rpms. What I do is flat line my PE afr at 12.5 and then adjust my upper VE table untill the WB matches this number. Then you can simply plug and chug in the PE afr table to find the AFR that give you max performance.

Just a little hint, there is usually less than 10hp difference between being a full point rich from max power. You can loose 30 hp or pop a hole in your piston by going only a tenth or two lean past max power. I aim for 12.5 AFR and leave the rest of the power on the table in the name of durability. There are much bigger gains to be had from lighting the mix off at the right time (timing advance).

 

Where is this in TunerPro under with 730 computer? What is it named exactly? BranZ

 

The conversation went off track for you BranZ. The two tables adding together thing applies to the other setup.
You are running a 730 ECM, Speed Density with $8D mask.
The best way to explain it quickly is for me to tell you to get the cruising BLM correct in the main and upper VE tables. That is your fueling.
Then once happy with that look at the two tables that control the WOT fueling (PE fuel actually).
One table adds/subtracts fuel based on RPM. 617->627
One table adds/subtracts fuel based on Coolant Temp. 60E->616
These will control the AFR during PE.
Many other things can have effect on the outcome so re-read the above article 100 times until the feeling of what you are adjusting makes sense.
HTH

 

JP86SS,

Thanks for clearing this up for me. You are correct it got knocked off track by the others. I have been working on the lower VE Table and will start this week on the upper VE table. Thanks again, BranZ

 

JP86SS,

What are the exact names of the two tables that your are referring to? I did not see anything that looked like them. Thanks, BranZ

 

Use the addresses, sometimes names are not the same.

 

Those two tables are used are for the Super 8d bin definition. I went ahead and downloaded it and starting playing with it. It is slowly coming together now. The one that I have been working with does not. Thanks for everyones help. Brandon