Wanting to learn how to tune

**wheels87k5** · 04-10-2016

Working on a 1987 K5 Blazer with 350 TBI, 700R4. ACSU $42-1227747 V5.1 xdf, 5.2adx. I've added the CFM throttle body, 1" spacer, salad bowl, AFPR, headers with dual exhaust. Minor mods but enough that a tune is in order.

I have the Moates Burner2, 3 of the 27SF512 chips and Tunerpro RT. I keep my stock ECM, with the ACSU chip the blazer came with, as a backup. I have another 7747 ECM, for tuning, that I soldered the G2 adapter in for the 27SF512 chips. I know how to burn to the chips, but that's as far as I can go. A while back I was working with Mark and we were just getting started. Mark had looked at a datalog for me and said that my VE tables could use some touching up. He was unable to continue because of his health. RIP bud.

My question starts with: Touch up what? Do I go into TP and open the VE tables? There's a spreadsheet with numbers that start low and climb going both directions. I know that I can change the values and it doesn't save it unless I want it to. But what cell am I changing and why? The other day I had someone look at a datalog and they seen that the blazer is running rich here and there.

This is some good advise I was given from my datalog:

For MAP I'm pretty sure you find the VE cell that corresponds to where you are rich or lean, and increase/decrease that value to change fueling. But that's where the differences in the programming comes into play...cruise is very easy (relatively) as in closed loop cruise, you aren't dealing with any of the additional timing or fueling that comes from the parameters that start to affect everything else.

I'd play with cruise settings a bit. Drive a short stretch of road where you can log cruise accurately, find where your BLM's are off, make the change that should bring BLM's closer (start small!) then drive the exact stretch again while logging. You should see the numbers getting closer to 128 if you are making the right changes, in the right area.

I understand what he is saying as far as getting the BLMs to 128. Low is rich and high is lean. But how do I get to that point? What do I open and compare to? I know it's a lot but I really want to understand. I have searched on here and on CK5. There is a ton of information to dig up and sometimes the links are outdated or do not exist anymore. And I'm not going anywhere so if you have the patience I have the time.

**steveo** · 04-10-2016

ve tables are really simple. it's a table that represents the airflow of your engine at any given rpm and vacuum (map).

if it's not delivering enough fuel, it's because the value is too low, if it's delivering too much, it's too high. if it's 10% too rich in a particular area, you decrease that area by 10%. then you take more logs and see how close you were.

a blm is hard to read in raw numbers. it's almost like GM intended the value to have 128 subtracted from it, but no datalogging software bothered to do it.

anyway, divide your BLM by 128 to get a multiplier.

lets say your trim is 112 at 2500rpm and 50kpa

112/128=0.875

now multiply the area near 2500rpm/50kpa by 0.875 (aka reduce by ~12%)

make sure your numbers are moving in the right direction (down for leaner, up for richer) so you know you're doing the right thing.

the idea is to make coarse adjustments at first and also modify surrounding cells so the 'curve' of the ve table is still fairly smooth. after you're in the right ballpark, it'll run awesome, and you can fine tune later.

**Woods** · 04-10-2016

A good tutorial, written up by EagleMark.
http://www.gearhead-efi.com/Fuel-Inj...-data-Tutorial!

**wheels87k5** · 04-10-2016

Thank you

This helps a lot.

**wheels87k5** · 04-12-2016

Here come the questions

I need to make adjustments to my fueling table....I understand that. I'm having some trouble understanding where this table is so that I can make those adjustments. In Tunerpro RT, do I open the tables icon located to the left of the screen? Go to "Fuel VE 1-Main Fuel table"? There is also "Fuel VE 2-Adder Fuel table" and "corrected fuel table" (map and rpm reversed). Is that the table with the values I need to concentrate on? If so, the first cell is blank, then starts small at 1.95 on rpm side and 10.94 on map side etc. and goes to 3200 rpm and 100 map to complete the spreadsheet.

The tutorial says to take the graph and smooth it out, which I did but wanting to make sure that I had the right table for making changes.

**wheels87k5** · 04-12-2016

This is the most recent datalog. Can you give me some input on what you see? I notice that on a steady cruise that the BLMs run good. But I'm still learning so be gentle.