04 stepside

[19cobia]

Ok I recived my least favorite codes today on 04 4x4 "edge stepside " po171 and po174 i found the throttle body bolts loose 3 turns each hate searching for air leaks

 

[RonD]

After engine is fully warmed up and idling, Unplug the IAC Valves 2 wire connector

RPMs should drop to 500 or engine may even stall, either is good it means no vacuum leaks

If idle stays high then there is a leak.

4.0l SOHC engines were known for cracked and rubbed thru PCV hose elbows
Pictures here: https://www.ranger-forums.com/4-0l-ohv-sohc-v6-tech-33/pcv-elbow-fix-very-common-cel-93776/

 

[19cobia]

Ok checked for leaks hot and cold nothing showed up unplugged the iac valve she did just what ya said. Went ahead and cleaned the mass air flow. Still getting codes po171 and po174.

 

[RonD]

Lean codes mean the Computers fuel ratio calculations are off by more than 15%, under 15% it won't set the codes

The computer calculates Open Time for fuel injectors "on the fly"

It bases the calculations on "KNOWN" parameters, it "knows" its running a 4liter engine, so it knows how many liters of air are coming in based on RPM and throttle position
MAF sensor is used to fine tune this for air temp and altitude above sea level.

It "knows" fuel pressure is 55psi, but there is no fuel pressure sensor............
So I would test fuel pressure, if it is 30psi then computer is basing calculations on false knowledge, and would set lean on BOTH banks

 

[19cobia]

Thanks thats going to be this weekends project fun part is truck runs great just a little slow to start.