4.0 injector upgrade?

[drueg]

Greetings, I have a weak injector which is throwing a lean code on bank 1, P-0171 code and the spark plug for the cylinder is slightly lighter than the others. It also has a rough idle.
When I have the top end off I'm thinking of installing 19lb injectors instead of the stock 17lb injectors. In the future I plan on adding headers and an aftermarket air tube/filter as well as maybe a throttle body spacer. Will my current computer be able to control the 19lb injectors or will I have rich fuel problems until I make the additional performance mods? Note that I live in Wyoming so emissions are not a concern.


Thanks
Dan

 

[RonD]

Original or upgraded won't matter, injectors are not like carb jets.

The MAF system can adjust for more air flow allowing for more fuel flow, but you are not really changing any of that.
Headers create lower pressure at exhaust valves in a specific RPM ranger, so can move power band lower or higher in RPMs but it doesn't change air flow into engine.
Stock exhaust manifolds are setup for mid-ranger power band.

Same with intake air, stock air intake setup is CAI(cold air intake) and filter is only 30% flow rated which means there is 70% head room as it gets dirty, so no restrictions there.

The computer opens injectors for a specific time based on MAF sensor data(air flow), if fuel pressure is correct, 14:1(approx.) air:fuel mix will be at intake valve, after firing of the fuel mix the O2 sensor sends computer rich or lean exhaust data and computer adjusts open time for injectors accordingly.
The 19lbs injectors might have a rich mix on first cold start, but once engine warmed up and O2 sensors came online that would go away and over 5 or so cold/warm cycles of engine the Long Term Fuel trims would be adjusted for the 19lbs injectors, so normal cold start mix, which is rich, i.e. choke mode in computer for cold start.
The MAF system has the ability to compensate for lower or higher fuel pressure, within limits, lol, and larger or smaller injectors, also larger cams.

Without access to the computer the 19lbs injectors will work the same as the 17lbs, and if you have computer access you could make the 17lbs injectors work the same as 19lbs, since they are more than engine needs in stock state.
If you were to turbocharge the engine then upgraded injectors might be required, but only above 8lbs of boost I would guess