check engine light po171 & po174 problem

[solar nut]

have run 2 tanks of seafoam,sprayed brake cleaner around all vac. lines & plenum,rpm did not increase.replaced MAF sensor,unpluged IAC rpm droped but did not die.pluged brake booster line & drove on back roads til light came on 20 miles,risky i know but had to eleminate posibility.nothing seames to work.code does not change.engine runs good,power & rpms are good.

 

[JP02XLT]

My truck has done this same thing under 2 conditions, 1st condition is if it idles for an extended period of time, 2nd condition is when it is very cold, at or below zero, it is intermittent, there is no freeze frame data present, if I turn the light off with the scanner it will not come back on for several days. I have checked all over the thing for any kind of leak, changed O2 sensors and checked everything I can think of, I have no clue what it is doing other than registering lean to the ECM, funny thing is I have a wide band O2 setup and have never seen a lean condition when the codes are set. I simply clear the code and go on.

JP02XLT