THIS CODE AGAIN!

So i bought my 02 corolla about a year ago, and it's had the same code almost the whole time. Its the system too lean bank 1. I was told it is usually a vacuum leak but could be a number of different things. It's had a tune up and has been kept in great running condition. It had the oil burning issue and has been rebuilt as of 4k miles ago, CEL still on. About a month ago i found a vacuum leak at an injector, replaced all of the seals, it ran WAY better but still had CEL. Last week a cleaned the MAF sensor, it ran even better, and it wen't off for about a day and then come back on. Same code every time. The fact that it went off makes me think it might have something to do with the sensor.

I also thought that maybe one of my O2 sensors is bad or even my CAT from burning a quart of oil through it every week.

Also, my car has made a high pitched whistling noise since the day i bought it which usually indicated a vacuum leak. It's coming from my throttle body and changes pitch when you hit the gas.(vacuum leak right?) but my mechanic told me that on some of the these cars the throttle body will naturally make a whistling noise... is he full of shit?

Sorry for the long windedness
Thanks for any input
Chris
Added: Mar 3, 2012 1:37 AM
PS i need to pass smog in a month. uuuuuuuuuuuuuuuuuuuuuuuck!

You could get a new car?

ha, i could. or i could try to fix it considering i just rebuilt it.

system too lean? i had this code and it never came back on...this is exactly what i did the same day...

cleaned maf sensor
replaced paper filter with a k&n
cleaned throttle body with maf cleaner
replaced donut gasket that sits in between the downpipe and exhaust manifold.
replaced exhaust manifold gasket
replaced green gasket that connects the downpipe and cat together
replaced front 02 sensor

this will pretty much kill the whole day if you do it by yourself but its well worth it...

most of the corollas after 100k have a farty noise when you accelerate, this is due to the old gaskets that usually dissolve from the heat...replacing all the gaskets and the donut will fix it, its been 10k miles and i never got that p0171 error code again...my car burned oil since i hit 200k and thats when i fixed everything and changed my sensor. just use a higher grade oil....im using 10w30 and it burns it less, i bought a new engine but i want to kill this one before i swap

i just got p0420, its either the cat or post-sensor but they also say the sensors on our corollas basically like to cry wolf.

if you need help i can actually help you with the code, im only 45min from sac.

i never thought of cleaning the throttle body. Im planning on aftermarket intake and exhaust but i don't think ill have it by the time i need to smog. I think I'm going to do everything you just mentioned plus port the exhaust headers while I'm in there.

thanks for the info

what's the p0420 code and how'd you get rid of it.

there is a guy on here selling the CAI for the 8th gen rollas, he just post it like a few days ago in the market place...most of the SRI for the corolla will sit right on top of the exhaust manifold and will just suck in hot air...9th gen corolla CAI also work but you need to relocate the battery

clean the throttle body with an old tooth brush and a clean rag

p0420 is the catalyst below thermostat...just bought a new denso o2 sensor and it cleared it....my old one was ssssooooo red/black/corroded from all the heat...i even had a white spot on top.

both my 02 sensors are completely white, is that bad? haha

i thought it was the 8th gen CAIs that sat on top of the manifold, it's only the SRIs? i was thinking of getting a 9th gen CAI

maybe time to replace them, i would change them if you see a decrease in fuel if not just leave them...

8th gen SRI are the only ones that sit on top of the exhaust manifold, some guy at car domain has a 8th gen corolla and he installed a 9th gen CAI fine