Hello I have an 01 blazer my tech 2 shows +3 on both banks at idle .

Upon no load throttle and held at 1500 rpm bank 1 goes +24% bank 2 no change

2500 rpm bank1 +24%. Bank 2 +17

for the first few miles or so it will buck and stumble then drive fine all day until the next cold start

 

Please report short term and long term trims for each bank and each rpm ( 4 numbers per rpm).

George

 

well i was hoping you would answer my call , i actually maybe , just maybe found the issue , being my evap purge valve , i was having some weird fuel trims that were going away as if an intake leak had sealed after 20 minutes of driving , unplugged my purge valve and trims went back to normal , it sure feels like the problem is gone but i will know for sure after tommorow . i did take some fuel trims today so i have some ready to take pics and post from my tech 2 .

 

The purge valve opens and closes to varying degrees most of the time that the truck is running especially after it warms up. It turns out the purge valve is open most of the time but on a controlled basis and the PCM accounts for that extra air. This may still be your problem but it’s not because it’s open during normal operation. Closing it off may actually be compensating for extra air elsewhere because the PCM thinks that purge valve is open and it’s not