Best Air Fuel Mixture 1990 K1500

[gensor]

Looking for recommendations on tuning the air fuel mixture on a 1990 K1500 5.7 for optimized efficiency between 40-80 mph on a stock motor.
1) Amazon "AEM (30-4110) UEGO Air/Fuel Ratio Gauge", using a wideband sensor
2) Tuner Pro with "OBD Diagnostics, Inc" 12 pin ALDL OBD1 GM Cable (USB), using pickups narrow band O2 sensor
3) Adjust the fuel regulator to 13psi and let the ECU manage
4) Other

And if a flavor of option 3 is implemented, will the engine provide an error code if the pressure is to low or high to manage correctly?

FYI: I tried using one of those 14 psi fuel regulator springs.... to much for the 5.7, it would stagger when the throttle was punched.

Thanks for the help!

You must be registered for see images attach

You must be registered for see images attach

 

[magimerlin]

Go to the "ultimate tbi" guide we have here.... do those simple things first, add a vortec pump and then go here...
http://www.rvmorsemachine.com/product.htm. (the websites still up so im assuming they are still there.. would only take a phone call or email to find out) or a place of your choice. I got ALL my stuff here and nothing's failed me yet...
Get an adjustable regulator, gauge and a gauge adaptor... adjust to roughly 12 pounds and call it a day...
But if you feel you must mess with the stock maps(yes I know they can ALL benefit from a few tweeks) on a stock motor you want to hit a stoich air/fuel ratio of 14.7:1. That is the most efficient burn ratio for a gas automotive motor. And that's 14.7 parts air to 1 part fuel.... your numbers may very though as that's just the mark you try to hit... as far as a "map" goes for the computer, there are a few people here that may chime in to help you on that... I know nothing, yet, about tuning the computer...

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[magimerlin]

Link to the ultimate tbi mods

http://www.gmt400.com/index.php?threads/11743/

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[gensor]

Thanks! However since I cleaned the TBI, I can now adjust the fuel pressure using ignition or needle nose pliers instead of spending $70 for the "86'-95' GM TBI Adjustable Fuel Regulator" from RV Morse Machine. As you can see in the image, I rotated the fuel regulator bowl so I can see the available spring adjustment easier. This is how they adjusted it in the factory.

 

[Chewy1576]

Have you made any other changes to the engine besides the FPR? Increased fuel pressure will deliver a little bit more fuel during the injector pulse than it would before, making the AFR slightly more rich (less than 14.7:1). The ECM will see this change with the O2 sensor, and compensate by shortening the injector pulse. Unless you make changes to the ECM program, it is always going to target a 14.7:1 AFR during cruising conditions. Acceleration and power enrichment conditions are a different animal, and usually target a richer AFR, like 12.5:1, to make sure there is plenty of fuel when the engine is making the most power. The values in the VE tables are "tuned" to provide an injector pulse at a given RPM and MAP for a 14.7:1 AFR out the tailpipe. Readings from the O2 sensor drive the block learn multiplier (BLM, long term fuel trim) and integrator (INT, short term fuel trim) values used to compensate for current engine conditions to bring the AFR back to 14.7:1 as read by the O2 sensor.

Have you used a gauge to check the fuel pressure to see if it is dropping at higher RPM? If you think that your AFR is leaning out due to fuel delivery between 40-80 MPH, you could possibly have a fuel pump supply issue, in which case I would recommend an EP381 pump from the Vortec trucks. Like for like replacement with the TBI pump, and will deliver up to 60 PSI of fuel pressure. Otherwise, if you want an AFR that isn't 14.7:1, you'll need to make changes to the chip.

 

[Tzfbird]

Since you used the words "optimized efficiency" I assume you are shooting for better MPGs?
Chewy is correct on the theory and operation but attaining the desired results is the hard part. The BLM and INT are based on 02 readings which can be very skewed by leaks in the exhaust system, poor electrical connection and probably a handful of other variables. Sure the stock chip(tune) will target a BLM of 128 (14.7:1) but there are multipliers (increase and decrease final injector pulse width) of all sorts such as whether EGR is on, coolant temperature and more that I can't remember. There are even changes to the ignition advance (+/-) as well for each of these variables. Advancing timing in the cruising area of the spark table for better combustion can help get the same or better power at a lower engine speed and save fuel.
There is always power and economy available from the factory parameters but knowing what to change and how much is the part that takes knowledge and skill.