Here's the situation. I had a CAI and sucked up a little water, barely any. white smoke came out my exaust for a little while but not very long. I cut the CAI and made it short ram and it with therm wrap, replaced the before cat o2 and the af cat o2 twice. its seems to run real lean between 1500-2500rpm at 1/2-full throttle then gains power but it still dosent feel the same. that and at 3000rpm and up at 3/4-full throttle it get real raspy/ricer like and used to not do that. My next guess is the fuel injectors but before I go spending more money to get them cleaned I wanted to see if anyone has any opinions or personal experience.

 

po420 is either having no cats, secondary o2 too far out of the exhaust stream, or exhaust leak. im banking on it being a leak since you said your exhaust sounds ricey.

btw do you have a wideband? you said it was running lean, how did you find out? anyother codes?

 

How do you know it runs lean? What are your fuel trims?

P0420 means a bad cat, exhaust leak, aftermarket high flow cat, What are your voltages doing from the seconday o2 sensor?

 

I do have a wideband but its useless, i havent installed the bunk yet. ive been too busy messing with this issue, it just feels like its running lean at that range. sounds like its drowning and hardly accelerates. im going to have a shop clean my injectors and im going to tighten everything up including the o2 tomarrow. i dont think its a leak cuz it dosent explain my pwr loss. your right it is contributing to the noise. wen i get my bunk put in on monday, unless an exaust shop is not open tomarrow, ill let you know the voltage (im stationed in guam, USA its 4pm now on sat). its not the cat, the car was great before the water incident. someone out here said he had the same thing happend and the same code but no one knew wat was wrong not even toyota. he said he just replaced all his internals and was good after that.


ill check leaks from header all the way down and redo all gaskets tomarrow along with tighten o2 just in case and get injectors cleaned. then check to see if any shops are open if not ill do it monday. ill let you know wat happens. plz check in on me in the next cuple days or ill just I.M. you.

 

I forgot the exact diagnosis for p0420 but i think there is supposed to be a 200 degree difference between the exhaust entering the cat and exiting the cat. It is supposed to be hotter after the cat if i remember correctly.

 

I got the secondary o2 put in and the AFR is ALL OVER, very lean. sometimes it goes beyond wat the gauge can read. idk if there is air seeping in through the weld or wat. Car sputters at 1500-2500rpm at half to full throttle. i went and did all my gaskets for the exaust. all i can think of is getting my injectors and throttle body flushed, along with replacing the spark plugs. the problems started after i sucked up the water. white smoke came out of the exaust for only for a little while after that happend. its nothing internal, i would be able to tell and it would have gotten worse. let me know what you guyss thing cuz im running out of options and its a pretty penny for the flush job.

 

P0420 reading:

- exaust leak (done)
-o2 sensor (aft) (changed twice)
-coolant sensor (def. not wats wrong)

 

mine did this once, leaned to 16 and most the time rich. im great now stay in 14's-13's a/f.

 

heres an idea unplug your battery for 5 minutes this will reset fuel trims for sure, then start the car and let it idle for 5 minutes

 

btw the wideband gauge doesnt get reading when you decelerating ....this is normal because injectors get turned off during deceleration

 

ill try it and let you know wat happens.

 

Ok here is what is up with the p0420 dtc.
p0420 catalyst below efficiency, which means the computer is seeing the waveform (voltages)as moving around too much or there is a lazy response (can be seen on a scan tool). you cannot determine from the secondary O2 if the car is leaning out, the seconday 02 has minimal impact on on how the car is fueled. the voltages generated are used by the ecm to detect oxygen content as is the placement of the sensor.

After the catalyst is not an accurate way to measure A/F ratios, that would need to go in before the cat.

Just give more info on your setup, high flow cat, exhaust mods.

this code is not difficult to diagnos, any one saying any shop could not diagnos this code is not telling the whole story.

 

i put the seconday o2 bout 7in before the aft cat o2... is it supposed to go at the beginning of the downpipe and/or at the bottom of the header???? got the megan reacing H/downpipe/E and aem CAI but i cut it cuz problems started wen i sucked up sum water...and. im running a consistent 14.8-15.2ish. if its in the wrong spot then its wrong but the car sputters at low rpm and its not making the same power. should i replace the downpipe?

i didnt disconnect the battery wen i installed the aft cat o2 but i didnt think that would hurt it.