Looking to get started on what to read before starting to tune on 7747

[spdfrk]

Hi all,

I've done a pile of mods on my old 1990 Silverado with a 7747. I've done some minor bin mods including an egr delete and the lean hiway mode mod. I have over 300,000 km on my truck and for the most part my stock programming has been satisfactory. I'm wondering where the best place is to start for tuning my bin to my truck's mods. I've done a pile of data logging with winaldl and I've been using the data collected to work backwards to figure out what the truck is doing and why. I want to start ultra conservatively on the tuning just because of the age of the truck. The only internals I've done are valve seals.

My web site for my truck is http://silverado30mpg.zzl.org if any one is interested in how I'm getting 8.9L/100km on a 23 year old Silverado.

If anyone has additional ideas I'd love to hear...

[EagleMark]

Nice looking truck!

Not sure how this:

I'm getting 8.9L/100km

compares to MPG but my old sqaure brick style 2wd Suburban has a highway best of 19.5. My around town is as low as 15, which is what it used to get on highway.

The data logging and VE table with TunerPro will be way better then WinALDL, look for the ADX file in this thread:
http://www.gearhead-efi.com/Fuel-Inj...Information-42

There's a tutorial with items to turn off for good data logs in this thread, although a differant ECM the procedure is the same:
http://www.gearhead-efi.com/Fuel-Inj...-data-Tutorial!

[spdfrk]

So I looked at the guide but my 7747's main VE table is only 2 dimensions. Is that the one to smoothen out?

[EagleMark]

There are 2 fuel tables in 7747 $42.
Fuel VE 1 - Main Fuel Table 3D
Fuel VE 2 - Adder Fuel Table 2D

You work with VE 1 Main table.

For the spread sheet to work correctly it needs all VE values in VE1.
http://www.gearhead-efi.com/Fuel-Inj...E2-Fuel-Tables

I've gone back to using both tables for 2 reasons. 1. big cam engines needs way less VE in idle and low RPM so I use VE2 to take away. 2. high RPM needs to start loosing fuel the higher the RPM gets so I use VE2 to take away again. This leaves VE1 smother and easier to work with. There's just not that much resolution there to begin with.

So I end up with a VE2 table like
10
10
12
15
20
25
25
25
25
25
25
25
24
23
22
21
20
20
20

For stock or near stock engines you can just run VE2 all set to 25. Add 25 to entire VE table, use spreadsheet, paste in new VE and subtract 25 from entire table.