VE Tables High

[MRott]

Hi all, I am having issues tuning the VE tables to start the tuning process on my Turbo 5.3. It's a whole new setup.

Motor: 2004 5.3L, LS6 CAM, De-capped Stock Injectors, rest of motor stock.
Injectors: De-capped stock injectors, cleaned and flowed 75 gal/hr @ 58 psi.

I also have a 76mm turbo, a 2 bar OS, speed density tune, MAF delete and converted using a stand alone IAT, no narrow band O2s, Wide band O2 sensor after the turbo, 2 bar MAP sensor.

I have the injectors set at 80 gal/hr because for some reason my fuel pressure is at 66 psi from a WIX33737. I thought this was unusual but the pressure is constant when driving. Either way it should cause the VE table to become smaller if I didn?t take it into account.

When I started the car for the first time it ran extremely lean (~20:1 AFR). I had RTT on so I increased the VE at idle to ~95 and I got perfect 14.7 AFR (I know they arent that accurate at idle but still), good vacuum (18in), and the spark was holding well. (See attached log file for short idle). Obviously 95 VE at idle is not possible so I was convinced it was an injector issue but I cant find anything wrong with the fuel injectors. Double checked the flow rate, cleaned them out, check voltage at each one, disabled each one, etc. I also have very good vacuum so I don?t think its a vacuum leak. Plus with the VE tables really high I can drive the car around and it does pretty well. I was wondering if someone could have a quick look at the tune and see if I am missing a multiplier or something. The car is also in open loop as I have the P0102 code. The VE table looks horrible as I was just trying to get the car to run. I'll revert back to the stock table and start over once I get this issue fixed.

Thanks,
Mark

[Area47]

get real injectors. You will never get it right with the decapped injectors.

[MRott]

I don't want to argue but lots of people decap these injectors with success. I have flow tested them twice and the flow rates are within 4% and the spray pattern has been analyzed. I'm not saying your wrong but before I throw money at the problem I just wanted my tune checked out to see if I was overlooking something that would cause this issue.

[kingtal0n]

If the VE table aint makin' sense yet, change the injector size and delay table until it does.

If I understand correctly,
You want the VE table airmass calculation to agree with the a/f ratio you see on the wideband, in other words predicted A/F vs actual A/F match, (commanded vs reality) the only way I know how to cause this is by adjusting injector size or delay table until it becomes "true".

Without good injector data it is hard to tell which to change. Luckily you said you have the flow tested? So if they actually flow what you think they flow and you are 100% sure (99%?) you can put that number into the injector size table and be good... If and only if the injector delay table is correct.

So lets say now you look at the delay table and notice that you needed to add 1.5ms of fuel to get the VE map to say 40-60 (typical idle VE?). Well 1.5ms plus whatever the computer is adding is WAY TOO MUCH. Its a common sense thing. That should immediately red flag you and you will say "well it must be the injector is smaller than I think it is or the fuel pressure is lower than I think it is, because no way these injectors need 1.5ms to open".

[cobaltssoverbooster]

technically when the flow data is correct you should be able to add 10% to the ve table and get a result close to 10% too rich back in the scanner.
if you cant do this then the computer isnt calculating the flow correctly for the system.
this exact reason is why flow bench data isn't always going to be perfect. It is always better than doing it the long way. its a method that produces values accurate enough to just input the flow data and send it so thats why we just rock it and go as shop tuners.

if you want ot do it the long way:
1) disable the offset table from 11-max voltage
2) tune the ve table in with a wideband and save the file
3) now add 10% to the ve table and check the afr error. if it reports less than 10% for the listed injector flow you need to decrease the injector size to force the ecu to command it open longer to meet the required fuel requirement. the opposite if the returned afr values are over 10%.
4) make your changes to the base injector flow based on the difference in afr error compared to the forced 10% increase.
5) repeat steps 2-4 until your within 1-2 % shift error.

6) now that the base flow is set put the injector offset data back to the data you were given.
7) just like the base injector flow repeat steps 2-4 but this time the offset table adds on-time so if the error is lower than 10% you need to increase the voltage modifier. if its over 10% then you need to decrease the voltage modifier.

by the time your done your final ve will be very smooth and any corrections that are made will be true percentage corrections which is how it should be.
it is by far the hardest thing to do, especially without a Eddy Dyno and lots of time on it. You may be able to shorten this method by being happy with a wider percentage of error before moving on and calling it good.
This is how you tune unknown injectors for megasquirt before you had companies like injector dynamics who offered megasquirt specific flow data. its not gods word so take it however you decide too. been doing it in emergencies since 05 without issues.

[MRott]

technically when the flow data is correct you should be able to add 10% to the ve table and get a result close to 10% too rich back in the scanner.
if you cant do this then the computer isnt calculating the flow correctly for the system.
this exact reason is why flow bench data isn't always going to be perfect. It is always better than doing it the long way. its a method that produces values accurate enough to just input the flow data and send it so thats why we just rock it and go as shop tuners.

if you want ot do it the long way:
1) disable the offset table from 11-max voltage
2) tune the ve table in with a wideband and save the file
3) now add 10% to the ve table and check the afr error. if it reports less than 10% for the listed injector flow you need to decrease the injector size to force the ecu to command it open longer to meet the required fuel requirement. the opposite if the returned afr values are over 10%.
4) make your changes to the base injector flow based on the difference in afr error compared to the forced 10% increase.
5) repeat steps 2-4 until your within 1-2 % shift error.

6) now that the base flow is set put the injector offset data back to the data you were given.
7) just like the base injector flow repeat steps 2-4 but this time the offset table adds on-time so if the error is lower than 10% you need to increase the voltage modifier. if its over 10% then you need to decrease the voltage modifier.

by the time your done your final ve will be very smooth and any corrections that are made will be true percentage corrections which is how it should be.
it is by far the hardest thing to do, especially without a Eddy Dyno and lots of time on it. You may be able to shorten this method by being happy with a wider percentage of error before moving on and calling it good.
This is how you tune unknown injectors for megasquirt before you had companies like injector dynamics who offered megasquirt specific flow data. its not gods word so take it however you decide too. been doing it in emergencies since 05 without issues.

This worked for me. I have the set injectors at 50 lb/hr @ 0 KPA which is far from what the were flowed at but at least everything is working. I'll see if I have any problems when I start WOT tuning.

[cobaltssoverbooster]

like i said its an emergency technique for when i start getting values that aren't on par with other peoples files or past known good files from the eddy dyno.
if its working, thats good to hear.

[shinyrust]

I guess i am in the same boat as far as trying to tune the VE table.

I am using the factory injectors from a Trailblazer SS with its intake and a china TB at 90mm. No vacuum leaks TSP stage 3 truck cam low lift (similar to a GM hot cam) and a lot of my VE table cells are above 100. It currently runs ok up to 2500 and some load but if I give it half throttle it will lean out, cut timing and pop out the exhaust. Attached is the tune that I am using to work on the VE and a log after the last adjustment I made.

[shinyrust]

Do you think it is possible that I need to do the same thing you just described?

[cobaltssoverbooster]

shiny you got some issues with injectors and more likely not cleaning up your data. for the most part your ve is fairly smooth. its not the ideal level of smooth but learning how to use the advanced histogram filters may be able to help you smooth it out even further.

this technique is really a last resort for when you are struggling with data. its perfectly normal to have values over 100 in the ve but when you start creeping up on 1/2 or 2/3 of the entire ve range is over 100 then you should double check your data.
in your case i would try to solve any issues by testing new data changes where the advanced histogram filters are in place. if your results still produce non-productive results then maybe i would start to question the data of the system. Make sure you dont have any really old mechanical parts as they also have effect on the data. like a 5 year old fuel pump or filter. also check your pe tipin transitions...i think your 3.0 enrichment ramp in may be a little heavy. i try to keep my transition afr for tip in something around what im commanding for pe values. maybe 12-12.5 ish its just a suggestion to make sure your not just dumping heavy fuel during that transition.

[shinyrust]

shiny you got some issues with injectors and more likely not cleaning up your data. for the most part your ve is fairly smooth. its not the ideal level of smooth but learning how to use the advanced histogram filters may be able to help you smooth it out even further.

this technique is really a last resort for when you are struggling with data. its perfectly normal to have values over 100 in the ve but when you start creeping up on 1/2 or 2/3 of the entire ve range is over 100 then you should double check your data.
in your case i would try to solve any issues by testing new data changes where the advanced histogram filters are in place. if your results still produce non-productive results then maybe i would start to question the data of the system. Make sure you dont have any really old mechanical parts as they also have effect on the data. like a 5 year old fuel pump or filter. also check your pe tipin transitions...i think your 3.0 enrichment ramp in may be a little heavy. i try to keep my transition afr for tip in something around what im commanding for pe values. maybe 12-12.5 ish its just a suggestion to make sure your not just dumping heavy fuel during that transition.

I am having a hard time understanding what data to change. I need it spelled out in crayon lol. Do you mean to try different values in the injector flow table?

I used the factory injectors from a trailblazer ss and since the values don't align with my OS I used the excel spreadsheet to come up with the values I did. Im not confident in the values but its the best I could come up with after researching for hours how to scale them.

I have tried to figure how to set up different graphs. I win on some but lose it on others.

I ramped up the value for PE to 3 to see if it would actually make a difference in the lean out on acceleration. Also my timing drops out when I floor it and I understand that it retards initially then advances to the setting in the tune. Mine retards and stays retarded until I lift. Do you have any insight to why this is happening?

The fuel pump, filter, lines are all new and produce 60 psi steady.

I think I have the PE set to 12.5 across the RPM range.

As always thank you for you input! This knucklehead has a lot more to learn!

[cobaltssoverbooster]

histograms are the charts that get populated in the scanner. you apply filters to them in the histogram settings. you can do really cool things with that which takes forever to explain because its kind of like learning what the editor software is and what everything means or how it ties together.
i would just search around for a few days looking for information behind histogram filters. i know its out there because thats how i learned how to use the filter system. Its not something i am good at teaching unfortunately. i am good at helping explain types of filters once the base knowledge of them has been understood.

i would use the current injector data from the factory as you have now. like i said the ve table values are looking good. by using the filter system on the histograms you use for tuning the ve, you may be able to reduce the peaks and awkward shapes the current ve table has.

[kingtal0n]

I've never even really used the histograms. Most stand-alones of the 90's didn't have that stuff. I've acceptable economy & performance without using custom histographs.grahms. histothingys

The key to normalizing or calibrating the VE table is the delay and injector size tables. Advanced tuning would take advantage of airmass calculation because it affects so much. For novices it is best if the actual airmass matches real airmass for some portions of the VE table than others. For example in my 60-80kpa range I have slightly higher than realistic VE values to get the a/f to dip into the 14.0's and 13.8's without getting into power enrichment mode.

[cobaltssoverbooster]

thats advanced methods and only works properly when running strictly in open loop.

[shinyrust]

So my 'VE table isn't too far out then, just needs some fine adjustments(probably the cells I can't hit on the street) and some smoothing.

[shinyrust]

So I think I found 2 errors. First problem was defiantly IFR and Offset. I had to look at a TBSS and research where my table would fit in the table for a gen 4 motor. So 400 was where I needed to start and go out to 480. Then I interpolated the values in between. Did the same for the offset. Started at 400 and went to 480. Second problem is the knock retard. I zeroed out burst knock temporarily and went for a drive. Truck runs sooo much better. I need to diag the burst knock problem next but for now I claim a win. Side note, I also got rid of anything that changed the main spark table. Take a look at the log if you have a min and the SD tune I ran with it.

Thank you cobaltssoverbooster !!

[cobaltssoverbooster]

im super burnt out from working on a sfi 2.5C chassis that hit the wall so i really only got a good look at the tune file.
it seems your injector data corrections have smoothed your ve out a great amount. the last little bit will come with time and maybe refining how you filter the data to provide the most useful logs.
good job at correction your conversion data and interpolating. keep it up.