4.3 injectors in 5.7 for MPG

[travis mattson]

Anyone tried this.
I swapped a 350 in it from a 305 years ago and it runs awesome but it drinks gas like crazy. It does seem rich , never returned. Running 350 injectors with 305 ecu because the 350 ecu ran like ****.
With gas prices lately wondering if I could squeeze some mpg out of. Running yellow pressure spring thing to.
I'm sure everyone will say it will be lean but it's rich now so idk.

 

[1998_K1500_Sub]

it drinks gas like crazy

What sort of MPG numbers are you getting?

What's the vehicle? Is it the truck in your picture? SCSB? Suburban? 2x4 or 4x4? Big-a$$ tires? Manual trans?

No ECU codes?

Have you ever put a scan tool on it to check the fuel trims?

If pre-1996, which MEMCAL are you using... that from the 305 or from the 350? You said "ECU" but pre-1996 the same ECU might be used for many engine displacements, the difference is in the MEMCAL.

 

[travis mattson]

What sort of MPG numbers are you getting?

What's the vehicle? Is it the truck in your picture? SCSB? Suburban? 2x4 or 4x4? Big-a$$ tires? Manual trans?

No ECU codes?

Have you ever put a scan tool on it to check the fuel trims?

1994 2wd sbrc. 4l60e
235 70 r15
Mileage is 12 in town 16 on highway
Never looked at trim codes.
I have some 5.0 injectors I found ,may try

 

[Supercharged111]

Short answer, no if they're different. If you want to tune for economy, do that, leaning the truck out with too small of injectors is beyond ghetto and begging for trouble.

 

[Schurkey]

The O2 sensor will provide a lean signal to the ECM, which then compensates by driving the injector longer.

Net gain = 0

Driveability suffers, as does power.

Overall, very silly.

Mileage is 12 in town 16 on highway

And you're complaining about that?

I'd be happy. A little better than I'm used to, but mines 4WD and long-box.