im-not-guilty

iTrader: (4)

1999 SS MANUAL
CAR RAN FINE WHEN PARKED 2 YEARS AGO.....
JUST INSTALLED LONG TUBES k&n and SLP air box
sent out for mail order tune ...
runs well but no power after .. fuel trims high... found and replaced split pcv hose and threw a set of intake gaskets at it ...... drove again had questionable 02 sensor ... so just installed 2 new acdelco sensors.....now sensors switch as they should at idle .... but both will drop to zero under load ...also I have swapped ecm pins 68/69 28/29 25/26 65/66 so I can plug sensors into rear connectors
maf is in low 100's under hard accell .... I have another im going to go swap out now .... what am I missing ????

soloman369

iTrader: (13)

So your saying underload the LTFT drop to 0 on both banks ?

im-not-guilty

iTrader: (4)

YEAH I GOT IT .... was the stupid used MAF that came with the used slp airbox....
thought it read fine on the scan tool .... whatever runs aces now

67Lark

I think he is saying O2 drop to 0 under load, what do the LTFT and STFT do under load?

67Lark

Nevermind lol

im-not-guilty

iTrader: (4)

mass air flow was the prob ..... both 02's would read zero under load read fine at idle fuel trim was fine at idle ... did not check going down the road ... runs strong now

joecar

He saying that the NBO2 voltages dropped to zero mV at load, which is excessively lean, which appears to have been caused by the under-reporting MAF sensor.