Adjusting VE Fueling tables with BLM data Tutorial

[rsicard]

Gentlemen:

Really like and greatly appreciate Dave W. creating the "Adjusting VE Fueling tables with BLM data Tutorial". There is one question that is puzzling me. The recorded BLM data can be quite sparse. Is there a way to intelligently populate the empty cells so that it gives appropriate correction data for the pasting process to come to a mathematical correction factor for the old VE table to come up with the new VE table incorporating the correction factors? Is there a need to apply a interpolation between BLM numbers in the same row on the BLM data sheet? Hope someone can shed light on this aspect.

[dave w]

VE tuning is part science (data logs) and part art (experience). In general an engine needs more fuel as RPM and load (Kpa) increases. 90 Kpa is a greater engine load than 30 Kpa. The exception to greater load is at engine start up. As the engine starts, the MAP is reading nearly 100 Kpa. Very quickly after the engine is running (above 400 PRM's) the Kpa will go lower (usually 35 ~ 55 Kpa)

***The computer will look at surrounding cells to determine how much fuel to deliver.***

Most VE corrections will cause peaks and valleys in the VE table. It is up to the tuner to interpolate if the engine needs more / less fuel in the surrounding cells of the peaks and valleys ( general rule as engine RPM / Load increases more fuel is usually required). The exception to the general rule ... engine RPM / Load increase more fuel is required ... is "cruise" driving conditions. Cruise driving is usually Lower RPM's @ Higher Kpa's.

Maybe the attached pic helps?

dave w

[rsicard]

Understand the graphic and Kpa values. Wondering how to manipulate, be it in TunerPro or spreadsheet, the cells surrounding the peaks and valleys in the VE table that are the appropriate values for the table. Any insight would be greatly appreciated.

[dave w]

VE Tables are edited / changed in TunerPro. The % of change to the VE Tables is determined by using Excel. Editing / Changing the VE Table can cause SEVERE ENGINE DAMAGE! Changes to the VE Table are AT YOUR OWN RISK!

dave w

[brian617]

Assuming you read the thread started by EagleMark here http://www.gearhead-efi.com/Fuel-Inj...data-Tutorial! Post #17 addresses your concern I believe.

[rsicard]

Dave W.

Understand most of what you have stated. It sounds rather dangerous. Yet I have to adjust the VE tables to get the BLMs to near the appropriate values. Is that to say that a significant change in the VE table can lead to engine damage? Perhaps smaller changes can keep from engine damage? I have received the injectors back from MrInjector. Debating whether to go to BATCH port injection with the factory ECU or first go to TBI injection with the 454 throttle body which by the way has a security torx adjustment in the fuel regulator. Found a bit that will fit the adjustment. Also have a complete harness that I can run the engine on my run-in stand. Again, I want to replace the 350 with a 350 Vortec with a 4 barrel manifold and an adapter to 454 Throttle body. Ordered and received a Bosch higher pressure in-tank fuel pump. Already have a MSD in-line fuel pump for the run-in stand (no dynamic load). Need to add the sensors to the intake manifold (MAP, CLT, O2, distributor, knock etc.). Then run the 350 Vortec and adjust fuel pressure on the throttle body at idle to get near normal idle AFR values same as on the pickup at the present time at idle. Right now the 454 throttle body has a STRONG (stock '94-'95 454) regulator spring. Also have one that is around 20 Lb. Then once in the truck, further adjust the fuel pressure regulator across the board. Any suggestions would be greatly appreciated.

[rsicard]

Brian617:

Thanks very much for the suggestion. Went and read it and as I suspected the number follow a curve. Don't know I MS Excel has as a curve fitting function to help fill in the number in the empty BLM cells. Maybe best to estimate from adjoining cells what values to stick in blank cells.

[brian617]

Finding the correct fuel pressure can be frustrating, however it is something the needs to be set and left alone, a Constant if you will. The best advice I can give is to try and assume the horsepower your engine is capable of and use these calculators http://witchhunter.com/injectorcalc1.php to arrive at lbs/hr that is sufficient. Once you determine the lbs/hr you need the injector constant needs to be set to match in your .BIN After that no further fuel pressure adjustment should be made unless your original figure is way off.

I'm absolutely useless with Excel/spreadsheets etc. For me I found just tuning the fuel and spark maps by hand worked. Its a bit unorthodox, but I'm more of a visual type than numbers type. I manually raise or lower areas of the maps each cell at a time all while trying to keep a nice smooth table.

Trying to tune on an engine stand is probably useless as no load will be represented.

[lionelhutz]

Similar to what Brian posted, I understand how XL and the automatic correction spreadsheets are supposed to work but they just never seem to work very well for me. If I only used the automatic corrections I always end up with a table that is a jagged mess. Overall, I find that I start with the BLM or fuel trim values as a percentage of the correction they represent making sure I only use cells with a higher log count. I then just hand correct the table where it's off first before hand smoothing and blending the rest.

When I used the automatic corrections, I found I was just knocking a bit off any of the peaks and then hand blending the table anyways so it wasn't saving any work.

[dave w]

Dave W.

Understand most of what you have stated. It sounds rather dangerous. Yet I have to adjust the VE tables to get the BLMs to near the appropriate values. Is that to say that a significant change in the VE table can lead to engine damage? Perhaps smaller changes can keep from engine damage? I have received the injectors back from MrInjector. Debating whether to go to BATCH port injection with the factory ECU or first go to TBI injection with the 454 throttle body which by the way has a security torx adjustment in the fuel regulator. Found a bit that will fit the adjustment. Also have a complete harness that I can run the engine on my run-in stand. Again, I want to replace the 350 with a 350 Vortec with a 4 barrel manifold and an adapter to 454 Throttle body. Ordered and received a Bosch higher pressure in-tank fuel pump. Already have a MSD in-line fuel pump for the run-in stand (no dynamic load). Need to add the sensors to the intake manifold (MAP, CLT, O2, distributor, knock etc.). Then run the 350 Vortec and adjust fuel pressure on the throttle body at idle to get near normal idle AFR values same as on the pickup at the present time at idle. Right now the 454 throttle body has a STRONG (stock '94-'95 454) regulator spring. Also have one that is around 20 Lb. Then once in the truck, further adjust the fuel pressure regulator across the board. Any suggestions would be greatly appreciated.

TBI is designed to work with a constant fuel pressure. Usually 61 lb injectors with 15 PSI will be sufficient for a stock Vortec 350, based on my personal experiences. I've been successful tuning a stock Vortec 350 using 80 lb injectors with 13 PSI. I personally prefer port injection. Port injection is usually more expensive than TBI. For a first time tuning experience, TBI can me more friendly to begin learning with.

[rsicard]

Brian617 and lionelhutz: Gentlemen, that is very sound advise. As lionelhutz said, I will use the higher count as a correction percentage on the VE table and hand correct accordingly. Brian617, really appreciate the link to calculate lbs/hr. Again, thanks to both of you.

[rsicard]

Dave: Thanks very much for the very instructive reply. For right now I will likely go with the TBI injection. Maybe port injection later on after gathering experience. Thanks ever so much for the data on the injectors and fuel pressure. I think that the 454 throttle body with the stock spring will yield 18 psi with the stock 30 PSI? fuel pump. I will have to go down in fuel regulator spring pressure and be able to adjust it to the recommended 13 PSI. Then I will leave it alone. It is quite likely that the in-tank fuel pump is the original stock unit which has 130,000+ miles on it. Right now don't know when it will quit. May just go ahead and replace it with a new unit for more trouble free miles. Getting great fuel mileage with the 350 TBI engine but it has leaky freeze plugs and loosing oil regularly. That is why the idea of going to the Vortec which I have and it is good condition. Need to mock this all on the run-in stand and get things semi-settled before exchanging engines. Subsequent TBI tunes will be done in the pickup with the 350 Vortec. Hope to have good fuel mileage with it.

[rsicard]

Dave W.

What part number is your 80 Lb injectors? With only 13 PSI they must be delivering a good amount of fuel. I have the 17104288 injectors one set just done by mrinjector and another set of the same part number from by 454 Suburban throttle body converted to batch port injection. What would be your estimate of fuel pressure that I should run on the 350 Vortec with these injectors. Your insight would be of great value. Thanks.

[delcowizzid]

i dont really use spreadsheets once you find the shape of the curve it pretty much just gets bigger/higher on its way to less vacum i normally manually tune with wideband in open loop due to having realtime tuning gear that i can manipulate all tables while someone drives.half of the tables i can do in the driveway out of gear and quickly get the high vac areas inline withen a few minutes.key points are having the correct injector size and cylinder size values as well as injector offsets or enough of a grasp to fix injector offset table from weird values in certian areas of the ve table manually from live pulsewidth data.this is what a ve table looks like on a tpi chev after a few hours out cruising tweaking in open loop when all your injector data etc is inline.remember if tuning via blm logs slow steady throttle movements trying not to trigger acell enrichment etc if i ever do blm stuff its short logs of controlled throttle input so the blm data isnt skewed by throttle transitions
never mind the flat section at high rpm my ecu goes to 9200rpm but tpi chev not so much LOL

[dave w]

I've used the early 454 TBI injector #5234231 to flow about 80 lbs @ 13 psi.

My experience with the 454 TBI injector #17104288 has shown me they will need about 30 psi to flow about 72 lbs which should be good enough for a stock or nearly stock Vortec 350.

dave w