Looking for a good starting point for my 3.4 S-10

**jimmykicker** · 10-23-2019

Hey guys, I am not new here, but I haven't been on in 6 years. Some changes in life made me park my truck for the most part for a number of years. Here's a little background on my truck.

Truck was originally a carbureted 1984 S-10 with a 2.8L engine. I removed that engine in 2010 and put in a GM crate 3.4 which is basically a bored and stroked 2.8. Physically almost identical. I had a 390cfm Holley carb on it. In 2013 I converted the truck to EFI with mostly 1991 S-10 stuff. The truck had headers on it and the exhaust was mostly original and it leaked like a sieve. It was LOUD!! I parked the truck in 2014 due to not having time to work on it and did nothing. I knew I needed to tune it, but until I finally fixed the deafening exhaust, I had no idea just how bad it was pinging. Now my goal is to get that fixed and to see if I can squeeze better fuel economy out of it. Currently I am lucky to get 15. I know it can do better.

Here is my problem. The truck has a 3.4L engine with 4.3 fuel injectors, 4.3 TBI and a bored out 2.8 intake. Obviously, GM never made a tune for this combination, and I don't know where to start. What ECM would be best for this application, and what bin file would be good to start out with? Has someone contributed one? Currently the truck has a 8062ecm in it from a 4.3L s-10 truck. it pings like crazy on 87 octane.

I am also looking at the purchasing the APU1 from Moates. What else will I need to really have a package that really works?

I apologize for my newbieness. I am trying to get info everywhere I can.

**dave w** · 10-24-2019

One option would be use the 1227747 ECM. The 1227747 is one of the best supported TBI ECM's!! The 1227747 was original equipment for many 4.3 V6 Pickups and Vans. The '7747 and '8062 wiring harnesses are nearly identical but some pin changes might be needed to switch from the '8062 to the '7747.

http://www.gearhead-efi.com/Fuel-Inj...Information-42

The Base Pulse Width (BPW) will need to be re-calculated for the smaller 3.4 liter. The 2.8 V6 timing tables from the '8062 will need to re-configured for the 122774.

dave w

**jimmykicker** · 10-28-2019

Originally Posted by dave w

One option would be use the 1227747 ECM. The 1227747 is one of the best supported TBI ECM's!! The 1227747 was original equipment for many 4.3 V6 Pickups and Vans. The '7747 and '8062 wiring harnesses are nearly identical but some pin changes might be needed to switch from the '8062 to the '7747.

http://www.gearhead-efi.com/Fuel-Inj...Information-42

The Base Pulse Width (BPW) will need to be re-calculated for the smaller 3.4 liter. The 2.8 V6 timing tables from the '8062 will need to re-configured for the 122774.

dave w

That's what I keep reading. The computer currently running the truck is from a 4.3 S-10, so it actually could be a 1227747. I will have to look. I don't think there are any pin differences between the two ECMs, but I cannot be 100% sure without looking at the diagrams.

Now, splain how I'd go about your last 2 sentences....That's the kind of stuff I am clueless about.

**dave w** · 10-28-2019

BPW Excel spreadsheet attached. Input displacement, number of cylinders, and injector flow into the spreadsheet to calculate the BPW.

Link to 1228062 Information, including wiring diagrams: http://www.gearhead-efi.com/Fuel-Inj...Information-4E

Link to 1227747 Information, including wiring diagrams: http://www.gearhead-efi.com/Fuel-Inj...Information-42

Use TunerPro to copy / paste the 2.8 timing tables.

dave w

**jimmykicker** · 10-29-2019

Originally Posted by dave w

BPW Excel spreadsheet attached. Input displacement, number of cylinders, and injector flow into the spreadsheet to calculate the BPW.

Link to 1228062 Information, including wiring diagrams: http://www.gearhead-efi.com/Fuel-Inj...Information-4E

Link to 1227747 Information, including wiring diagrams: http://www.gearhead-efi.com/Fuel-Inj...Information-42

Use TunerPro to copy / paste the 2.8 timing tables.

dave w

Thanks Dave. I get some of this, but boy do I wish I could find some video on just the simplest stuff where I am scratching my head. I don't know why I am struggling so much with this. I installed the EFI system myself.

**dave w** · 10-30-2019

I think the "skill" you are wanting to better understand is the binary or .bin file editing. The .bin file is the information or programming that is flashed or burned into the chip.

Basically, parameters like the BPW, fuel tables, and spark tables will need to be edited / modified in the .bin file to better match 3.4 liter. The 1227747 is one of the best supported TBI computers. Modifying a 1227747 4.3 liter chip with 1228062 2.8 liter fuel tables and spark tables will likely work better on the 3.4 liter vs. using stock 4.3 liter fuel and spark tables.

Try searching YouTube for TunerPro videos.

dave w

**dave w** · 10-30-2019

Maybe this gearhead-efi link will help? http://www.gearhead-efi.com/Fuel-Inj...must-read!-%29

dave w

**jimmykicker** · 10-30-2019

Originally Posted by dave w

Maybe this gearhead-efi link will help? http://www.gearhead-efi.com/Fuel-Inj...must-read!-%29

dave w

Thanks Dave. That is VERY helpful!

**jimmykicker** · 10-30-2019

Originally Posted by dave w

Maybe this gearhead-efi link will help? http://www.gearhead-efi.com/Fuel-Inj...must-read!-%29

dave w

Thanks Dave. That is VERY helpful!

I've read over the info you have on there, and I am getting the connection and the usage of the files now. The thing I am confused by is how to interpret that data to make changes. Where can I get some information on how to do that?

**dave w** · 10-31-2019

Let try stepping though the .bin information.

1. What is the injector part numbers in the 4.3 Throttle Body?

Gearhead-efi injector information: http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

4.3l engine NOTE: Some came with 2 differant size injectors?

Knowing the injector part numbers will be needed for BPW.

dave w

**jimmykicker** · 11-04-2019

Originally Posted by dave w

Let try stepping though the .bin information.

1. What is the injector part numbers in the 4.3 Throttle Body?

Gearhead-efi injector information: http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

4.3l engine NOTE: Some came with 2 different size injectors?

Knowing the injector part numbers will be needed for BPW.

dave w

I will see what I can find out Dave and post back.. Thank you.