03-04-2014, 11:54 PM
420s are a pain, the rear 02 thinks the Cat is dead or slow or lazy.
1/2 the time the ECU is wrong here. (or the 02 rear is just bad)
the key to getting good 420s. (besides, replacing cat) is to get engine running in closed loop at idle. and at fast flat steady cruise. if it does that , the cat will run warm and wake up and pass 420s (with deity blessings)
your cat is not melted, im sure.
ran rich before, this can make the cat , full of fuel and you need to run it at cruise and get it hot as a pistol and it will back dry and wake up. Id did that on one full of raw oil.
the 96 kick ECU will suspend 420 test if it think the front sensor reads bad, but it can be fooled, and yours thinks the front is ok
but why is the LTFT at -15% (i think that means the ECU is subtracting fuel due to 15% too rich.
i dont thing the MAF is too high. by 15%
so where is the extra fuel coming from , but the way 15% is not bad, its just tad high. -5% is very good. the oxy sensor front sees the is rich and the system corrects it with -15% adjustments. i only mention it because, there may be a leaking injectors, a dribbler. and will make idle bounce from time to time. as that cylinder fouls and clears.
id try injector cleaner. Chevron is the best, i dont like additives but this one is only what's in Chevron fuel already, lots of benzine. a vary powerful solvent.
use bottle instructions for quantity
is your 02 a fresh sensor?
when i got my 04 , some PO put in some weird additive and sparks and o2s were all purple in color, so i ditched them....(front only)
sure 420s can be a dead rear 02, the ecu expect a flat line, from it , and then bumps. as the ECU tries to keep the CAT fully hot.
the ECU works hard to keep the CAT alive and lit off an the 420s checks that that happens, and the complex wave form from that 02 rear. fooling it is very hard.
most folks ignore 420s, and drive.
i looked at your scan it looks great. just tiny drop in LTFT (neg)
minor leaking injectors will show up at idle. mostly.
you will hear a misfire.
im sure Techron will clean clean them. if the gods are willing,
o2 sensors not dead, are impossible to test. they can and do get poisoned and then are offset. they lie. they swing and look perfect but lie. (offset biased)
hope my ideas , help in some small way, and good luck to you. are you in federal smog zone (test)
1/2 the time the ECU is wrong here. (or the 02 rear is just bad)
the key to getting good 420s. (besides, replacing cat) is to get engine running in closed loop at idle. and at fast flat steady cruise. if it does that , the cat will run warm and wake up and pass 420s (with deity blessings)
your cat is not melted, im sure.
ran rich before, this can make the cat , full of fuel and you need to run it at cruise and get it hot as a pistol and it will back dry and wake up. Id did that on one full of raw oil.
the 96 kick ECU will suspend 420 test if it think the front sensor reads bad, but it can be fooled, and yours thinks the front is ok
but why is the LTFT at -15% (i think that means the ECU is subtracting fuel due to 15% too rich.
i dont thing the MAF is too high. by 15%
so where is the extra fuel coming from , but the way 15% is not bad, its just tad high. -5% is very good. the oxy sensor front sees the is rich and the system corrects it with -15% adjustments. i only mention it because, there may be a leaking injectors, a dribbler. and will make idle bounce from time to time. as that cylinder fouls and clears.
id try injector cleaner. Chevron is the best, i dont like additives but this one is only what's in Chevron fuel already, lots of benzine. a vary powerful solvent.
use bottle instructions for quantity
is your 02 a fresh sensor?
when i got my 04 , some PO put in some weird additive and sparks and o2s were all purple in color, so i ditched them....(front only)
sure 420s can be a dead rear 02, the ecu expect a flat line, from it , and then bumps. as the ECU tries to keep the CAT fully hot.
the ECU works hard to keep the CAT alive and lit off an the 420s checks that that happens, and the complex wave form from that 02 rear. fooling it is very hard.
most folks ignore 420s, and drive.
i looked at your scan it looks great. just tiny drop in LTFT (neg)
minor leaking injectors will show up at idle. mostly.
you will hear a misfire.
im sure Techron will clean clean them. if the gods are willing,
o2 sensors not dead, are impossible to test. they can and do get poisoned and then are offset. they lie. they swing and look perfect but lie. (offset biased)
hope my ideas , help in some small way, and good luck to you. are you in federal smog zone (test)
http://www.fixkick.com