usually indicates a MAF sensor problem

 

99% MAF sensor

Remove the maf sensor and clean the two wires inside it with BRAKE CLEANER, not carb cleaner. You may have to use a detailing q-tip, but most likely not. If you have a computer you can reset the code, otherwise it may take a few driving cycles to reset itself.

I have an 00 XLS that had the same problem. The dealer says that you have to replace the MAF to the tune of 3 - 400 bucks. This works 99% of the time.

For more detailed instructions check out this post:

http://www.toyotanation.com/forum/t96508.html

 

I kinda cleaned that MAF sensor already. Maybe I half-assed it. The code has not come back on since I switched the Ignition coil packs, but it still feels bad. Why would that sensor only cause bank 1 to read a fuel trim problem. Is there a posibility that the EGR valve is stuck or that something in that weird dual throttle body assembly? Is it possible that there is something stuck in an injector holding it open or that maybe it went static? Thanks for the tip on the MAF. I am going to spend some time and do that correctly tomorrow.

 

if you suspect an injector, have you tried a good cleaner such as BG products 44k? it costs a bit more but is the best cleaner out there and really works. when my city mileage dropped below 20, i use it and it immediatley gets back to 22-23. i've gotten where i use it every oil change.

 

Just went through this with my 2000 XLS. I finally purchased a refub MAF from Advanced Auto Parts for $80 and problem was solved.
I tried cleaning my MAF first and that did nothing.

 

I have an 01 avalon xls and ran through a puddle large enough to turn on the VSC system. As soon as it engaged, the check engine light came on. I read the codes and it is a fuel trim malfunction on bank 1. Here is the kicker... The light sometimes is not on when I start the car, but the check engine light will turn on when I am coming to a stop. It will turn on 75% of the time this way and 25% when I am at freeway speeds. Also, when the car is in park and I apply a decent amount of gas, it wants to hesitate. The car also idles just perfect. The performance on the road is not bad, but not 100% either. The car feels like it wants to shift gears, but decides to keep accelerating like i want it to. Basically it is not smooth under heavy acceleration. I do not have a ton of money to start replacing parts which may not fix anything. I have cleaned the MAF sensor and switched my ignition coils to the other bank in hopes of the engine code moving with them to bank 2. Can anyone help, or do I need to buy some kerosene and torch that car?!!

 

I have a 02 avalon and I had similar problems. After bringing it to the garage twice in 3 months they discovered that the transmission was faulty. I had 35K miles on the car. Thankfully I purchased an extended warranty when leasing the car. If you are short on cash and not covered under warranty I would torch the thing.

 

Thanks for the advice. I am just having a hard time sniffing out the problem. The CEL is off now, but the vsc light is on and the car still runs like crap. Is there some type of emission control or something mechanical on bank 1 that is not on bank 2? I removed the PCV valve on bank 1 and cleaned it. I did not see one on bank 2. I am thinking that something mechanical is causing the problem because when the CEL is on, O2 sensor voltages, A/F and other readings are all in spec. For some reason there is too much gas. That is why I initially thought of ignition coil pack not up to par or something clogging an injector. The car idles nice and smooth, but something is off... The plugs are also new and iridium tipped.

 

vsc lights-crappy running

Hey "eurobob".
My daughters' oo'xls has been doing same thing. -Except, NO CEL has ever come on!?
Car will have abs, vsc/tracs off lights illuminate and start running poorly.???
I have not pulled codes yet,(Actron on order),nor cleaned MAF.
I did pull all 4 abs wheel sensors and clean. Lights went away for 2 days.
Came on and went off so far.
Post what you do find and I'll do likewise.
Jeff.

 

I just threw another CEL light. I am excited to see if my swap on the ignition coils has moved the rich fuel code to bank 2. I am going to check tomorrow and post the results. I am real curious to the problem because it was just fine until I hit the puddle and the traction control kicked on and then the CEL turned on. I thought maybe I had a wire pulled loose from the large puddle or I thought I may have injested some water into the intake, but that was on the opposite side of the puddle and way to high to suck any water in. Maybe Toyota just has a bad program for that situation since the computer controls the acceleration and brake when the VSC comes on. It's a shame when I would rather drive my 85 prelude si over the 01 avalon since I know the prelude will start and not stall on me.

 

Recheck the MAF

I just threw another CEL light. I am excited to see if my swap on the ignition coils has moved the rich fuel code to bank 2. I am going to check tomorrow and post the results. I am real curious to the problem because it was just fine until I hit the puddle and the traction control kicked on and then the CEL turned on. I thought maybe I had a wire pulled loose from the large puddle or I thought I may have injested some water into the intake, but that was on the opposite side of the puddle and way to high to suck any water in. Maybe Toyota just has a bad program for that situation since the computer controls the acceleration and brake when the VSC comes on. It's a shame when I would rather drive my 85 prelude si over the 01 avalon since I know the prelude will start and not stall on me.

I own a 2000 Avalon and 2000 4Runner. If you are getting "too lean" and O2 codes and your car runs badly and then gets a little better after driving about a half a mile, you may have a bad MAF. I cleaned my MAF with no success. After installing a new MAF I bought at the dealership ($170.00?) the problem went away immedialtly. The 4Runner drives like a dream.