I have been tuning the VE tables using the $58 BBZB as the base bin on a 350ci. I read through the P4_turbo_sunbird doc about how the fuel BPW is calculated. I am confused about PE mode. It states that the PE mode AFR table is used if it is richer than the "calculated AFR".

I have been running in open loop with the DIY-WBO2 on it and have the AFR where I want it at idle, part throttle, and heavy throttle without boost. I then end up with a problem under boost conditions. It is too rich starting at 4000 RPM and above. I have reduced the VE adder table by about 20% above 4000 RPM but it really doesn't seem to change the AFR using the WBO2. The WBO2 is reading 10.0 AFR at 4000 RPM and goes down to 9.8 AFR at about 5500 RPM.

I have the BPC vs. EGR set according to the equation I found here at TGO. The VE tables seem to fall in line with the VE tables I had with the $8D code on this engine. The stock $58 BBZB has VE values of 95 and greater at high rpm and MAP which I find hard to believe for a stock production engine. I have removed 20% out of the VE adder table at 4000 RPM and above. It is still way to rich.

Is it possible that it is using the "PE AFR vs. RPM" table? I don't get it though because it would still need to use the VE tables. Anyone have this problem and know how to fix it? Or is it just that my VE adder table is still too rich and I need to pull out another 20%? If I did that then the non-boost condition with be 20% lean. I don't get it.

Thanks,
Junk

 

You need to adjust PE AFR vs RPM. I've noticed with $58 on the wideband, that HUGE ve adder changes make little or no difference to wb02 readings.

Grumpy is more familiar with the $58 code as he pretty much documented every line of it. I ran $58 for a little over 2 years before switching back to $8D. $58 is great for boosted apps using a somewhat stock, or lightly modified engine (light hot cam). With a HUGE cam, i don't think the VE tables have enough resolution with the 2-bar map sensor. I'm no longer running a forced induction application, but if I go back to boost in the future on another project I'll probably use a different ECM.

-- Joe

 

Remember a boosted engine will easily be over 100% VE. The stock BBZB was boosted. Even under vacuum it can be over 100% VE. 2nd thing is the tables probably don't really define ACTUAL VE but more relative.

 

I will try reducing the PE AFR vs RPM table. It is currently set to 11.8 for 4000 RPM and up (stock). If it is linear, then I will need to set it to (11.8*12/10) = 14.16. My current AFR is about 10 and I desire to have it at about 12. I guess I will try setting it to 13.4 to start.

I have been working on a commented version, but have yet to go back through a lot of stuff and write down the equations and logic of what it is trying to do. Sometimes I start to do that but then remind myself not to get sidetracked and finish commenting first. I suppose once I have it finished then more of this will become clearer.

Thanks

 

True, but there is no way a stock Syclone would be over 100% VE without boost. The VE table only goes to 100KPA. Maybe you are correct that the VE table isn't actual VE, but it does come extremely close to what the engine was with the $8D code and extremely close to what the engine comes out to mathematically. Who knows. It could be just coincidence.
The thing is that to really tune it right it needs to be tuned with the exhaust restriction and no boost to get the VE tables right. It almost seems like GM didn't do that and just left the VE tables rich at upper KPA and RPM. I would like to see how the 4.3 litre would run with the exhaust cork and no boost at upper RPM and KPA. I think it would be very rich.

My VE table is very close when not boosted. Then it is too rich when boosted. I need to do some more simulated hills for high load (70KPA+) and 4000 RPM and up to check the upper end of the 3D VE adder table.

Thanks

 

If your running a v8, shoot me an email at ty1295@gmail.com

I might have a solution for you, if you want to test something.

 

I ran the code on the bench and now see what is happening. I need to check the XDF file for the VE adder and look at the source code to see how it works. I thought the 2-D VE adder was added to the 3-D not in idle VE table. Apparently, this is not true. I ruled out the emulator be a cause of not updating the VE adder table. The PE AFR vs. RPM table also modifies the BPW as expected.

The problem I had with the car was that I was reducing the VE adder table for high RPM and this shows no affect to the BPW. The 3-D VE table does adjust the BPW as expected. The stock 4.3 litre VE tables make a lot more sense now.

Yes, it is a V8 with boost. Do you have a list of mods that were done to the bin? I will send you an email. I can test it out. I kind of have my hands full with working on a NVRAM hac, source commenting, and finishing a twin turbo install in my truck. I think I can squeeze in some testing though.

 

VE over 100 is VERY difficult, even turbo, if you calculate it REFERENCED to MAP.
VE is %Fill of cylinder based on size Relative to MANIFOLD Density. If you look at the BPW calc, MAP AND VE are in the same equation. Thus VE must be relative to MAP. If VE was calculated relative to atmosphere, MAP wouldn't be part of the calculation, just part of the lookup.

If I'm wrong, I'm wrong, but that's the only way I can see it being when the value of MAP is used in the calculation.

 

I think I found the problem. I read through the code and it clearly shows that the VE adder 2D lookup value is added to the VE 3D lookup value. I think I know what is causing my problem. The RR_V14.ecu file has the VE adder table displaying the "table spacing" value as the VE for RPM 0. I think I changed that to match the other VE values to make the table look more uniform. In doing that it screws up the spacing value used for the 2D lookup. Instead of a spacing of 16d it is proabably up in the 50ish range.

So, the stuff about the 2D VE not being added in that I wrote earlier is false. I will verify it with the bench tomorrow night.

 

Did you get a chance to verify that info? It would make sense that you're right, in that the stock BBZB 0rpm adder value is 6.24 while 400-3600 is 30.81. Besides, why would they put a 0rpm VE value in?

The way I have my VE's set up to try is that I copied my $8D values onto the 3D table up to 3600 (but subtracted 30 from 4000), then 0'd out all the adder RPM's up to 3600, and added 30 at 4000, then added less and less up to 6375 (not applicable past 5600), the sum of which equals my $8D values as well. There shouldn't be a problem with this, right? It just makes it easier to see real values. If it makes things more complicated I'll just start that over.

 

The 0 RPM value of 6.24 should not really be part of the VE adder table. It is the "spacing" that is used by the code when it does the RPM to VE adder lookup. The 6.24 value translates to 0x10 (table spacing). I verified this with reading the code. I also tested this out on the ECM bench and the VE adder works as a VE adder to the 3D VE table values.

I used the VE adder table to reduce my high RPM AFRs and it works properly. I went from 10 AFR to 11.xx AFR by adjusting the VE adder table.
I set the 6375 RPM to rich in case of over-rev, over-boost. I rev the engine to 6000 RPM (only 3 times with the turbo setup so far).

Looking through the code shows that the VE adder value is directly added to the VE table value. I haven't thought about it a lot yet, BUT some rounding is done when the VE value is "looked up". Therefore, two table lookups may or may not have better precision than one table lookup. I played with both tables on the bench and it seemed like the 3D table affected the BPW more than the 2D table. Don't quote me on that, it is early prelim. results from testing. The code shows that this should not be true so I have more concrete testing that needs to be done.

I don't see why trying to just use the 3D table for low RPMs would be a bad thing. The only thing is the rounding I was talking about and I don't know which is better as of right now. Using previously tuned VE tables from the $8D should get you close. I have been tuning the $58 from the stock tables and have been doing it like I normally would tune. I compare the VE tables to the $8D every once and a while. The $58 is getting closer and closer to the old $8D table. The high RPM VE is a little less with the turbine corks & log manifolds. It had 1 5/8" headers before.

I have been comparing ALDL data with data calculated from the "gncalculator.xls" spreadsheet and it predicts values that are very close to the real ALDL values. The 42#/hr are at 79% duty cycle at the worst case WOT with the boost turned down to about 7PSI with 160* F intake temps (no IC)..........just to give you an idea of how the 42#/hr injs. are working.

Side note, make sure you run an open element IAT sensor. Do not use the stock TPI brass MAT sensor. They don't respond quick enough for boost conditions.