odd codes after headers

[z3r0]

so i have
P0102 Mass Air Flow (MAF) Sensor Circuit Low Frequency
P1406 EGR Valve Pintle Position Circuit
P1645 Evaporative Emission (EVAP) Vent Solenoid Contorl Circuit
P1655 EVAP Purge Solenoid Control Circuit

now i know i removed the egr
the o2 was extended and the rear simmed so those codes were gone but as soon as they did the maf code popped when i cleared everything

(or rather i cleared everything than restarted the car then read the codes)

now i didn't touch the evap myself, however my tank does pressurize and when i open the cap i get a nice hiss from it like a soda

is it possible the old owner removed the evap and now i need the codes to be removed when the car is tuned?

 

[dsmuts]

I had some of those codes after installing my headers and i got the wiring harness pinched in between the header and head and it burned the wiring so i fixed that and zip tied it out of the way.

 

[gtpsleeper]

If the evap had been removed you would be seeing more than just the one code... Im wondering if your canister isnt purging for some reason...

what maf are you running?

 

[z3r0]

i'm running a stock 97 gtp maf
and i have 2 evap codes
the spurge solenoid and the vent solenoid
the lines are still in the rear. but i don't know where it stoppes quite yet

 

[gtpsleeper]

I think if you have a faulty canister (someone correct me if im wrong please) but it will cause those 2 solenoids to not function properly therefor setting off the codes...

also, because when you open your tank it makes a hissing noise so that means its not releasing pressure...

have you tried swapping gas caps?

 

[whiney]

check all of your fuses, I had a similar issues with chaffing wires and got some of the same codes that popped up.

 

[z3r0]

checked all the fuses and mini relays and still nothing