98 4.0 Smog problems

[Ranger4x4newb]

I've been needing to smog my truck since November and haven't been able to get it right. First I was running lean, after messing with the vacuum lines I changed the manifold and voila. Now my trim is down to 18% instead of 25+. I still can't figure out why it's so high. I also have ap0455 evap code. I've changed both solenoids with no luck. Does any one have any ideas why my evap is screwed and long term fuel trim is so high?

List of new parts
Fuel pump
Dpfe sensor
Dpfe lines
Egr transducer
Maf
Iat sensor
Manifold
Vent solenoid
Purge solenoid
Tps sensor
Both upstream o2 sensors
Vacuum lines from intake to egr transducer and egr
Egr tube gasket and upper manifold gaskets

 

[55trucker]

So what is the real time A/F ratio at idle when your scanner is connected?

also what is the BLM integrator reading when at idle?

https://www.autocodes.com/p0455_ford.html

 

[RonD]

EVAP codes will keep coming back until computer gets 2 successful tests of the system, keep fuel tank between 1/4 and 3/4, don't fill it up and don't run it dry.
You can not force a test, but if you drive it 30 miles it should test the system once.
Engine then has to cool down for at least 3 hours, and then another 30 mile trip should cause another test and if EVAP passes test both times code will reset.
Two drive cycles are needed, 1 drive cycle is full warm up(coolant above 180degF) and then cool down(coolant under 100degF)
So you could have fixed the problem but tests haven't completed

On the EVAP canister is a hose that runs back to the gas tank, remove this hose and suck on it, lol, free test, the gas tank with gas cap on should be a sealed container so needs to hold a vacuum or EVAP will set a code.
Common leak is the Filler tube, you can blow into the hose and have someone listen for the air leak if there is one

-7 to +7 are average fuel trims, idle can be up to +10
+18 when cruising means there is a problem

Check that O2 sensors are tight, I had one side that unscrew itself and was sucking in air so false Lean on that bank

LTFT takes awhile to come down, I think a Ford scan tool can reset LTFT but not any other scanner.
LTFT is there so as engine systems get older computer can compensate for the changes, i.e. lower fuel pressure, small air leaks, dirty injectors, dirty MAF, ect..........
So it is not suppose to be cleared.

What is your current fuel pressure?
1998 should be 60-70psi, lower fuel pressure means computer has to open fuel injectors longer to get enough fuel into intake.
Short term fuel trim(STFT) IS the open time for the fuel injectors
Computer gets air weight from MAF sensor, it then calculates the weight of the fuel needed for that weight of air.
It doesn't have a fuel pressure gauge, it assumes 65psi, and opens fuel injectors to add calculated weight of fuel, and that open time for fuel injector calculation is 0 STFT
+ 1 STFT means computer has to open injectors longer than calculated
-1 STFT means computer has to close injectors sooner than calculated

The -/+ change comes from upstream O2 sensor data, so is instant.
(Computer also swings STFT up and down constantly and this is normal, it is needed to make the Cat converters work)

+18 means calculation is way off, so computer lets driver know about it, and LTFT is an average for STFT so until STFT is reduce LTFT will stay high