brabbit

hey I havent had the car out since the appt at the dealership but I was told the light coming back was normal... the light did come back on immediatley after I took it off the lot that day- I haven't tried to get the weld done I'm waiting to hear from my uncle who does do some welding and has the equipt-

*Now... I had a hard time seeing exactly where the leak in the center pipe but I did see some corrosion and that same blackish residue nearwhere the bracket welded to the pipe directly upstream from the sensor..... I want to look for myself and want to know the best way to determine the exact problem anyone have any advice for me?
Obviously I need a 2nd and maybe a 3rd opinion but while I wait to hear back from my uncle I wanted to do some more investigating.

Carver

Brabbit, it isn't necessary for you to drive yourself crazy pinpointing the leak, a decent muffler shop will have welded up about 500 this week. Take a leap of faith, go to a good muffler shop, let them find it and give you a price to weld it up.

Then you can determine if you have any sensor issues.

brabbit

true but I'm still curious... lol

MASSMINI

Getting a lean code means that the sensor is detecting 'too little' burnt fuel in the exhaust. This can happen when exhaust is escaping upstream of the sensor. When the sensor detects a lean mixture the engine control computer will adjust the fuel mixture richer - which can cause reduced gas mileage.

Not necessarily happening in your case... But possible.

brabbit

so I got the center pipe welded up and it looks great... however the check engine light came back on- I still am not getting the gas mileage so my next day off I'm taking it to my uncle to get the codes read- I'm not driving it now but the symptoms are almost the same, a jerky almost stalling after letting off the gas pedal. Someone had suggested that the air fuel sensor for the rear bank may be bad... I also was wondering what to use to clean off the rear o2 sensor to see if it was bad??? Any other ideas please help-
thanks guys

Carver

Well, if you are going to all the effort to pull the 02 sensor to check it you might as well replace it. It's a consumable and you can use some of the money you saved on the exhaust deal to pay for it.

Don't try to poor boy the sensor, get the OEM Denso part. You can search for the part number, they are available on eBay and the online parts places.

brabbit

thanks..... so my plan here is to replace the sensor, I'll take your advice and go with the OEM denso; then reset the code; if by the chance the code pops up again what if any are your thoughts on what could be the problem given the problems I'm having with the rich fuel mixture and stalling/ low mpg. My guess and understanding is that the O2 sensor is most likely bad and that its still reading that lean code; which is the reason the cpu is calling for more gas, however this is all speculation at this point. I appreciate all the comments on my post,

Carver

There are several maintenance items that may be associated with your problem. The MAF may need cleaning, the IAC. Our cars really respond to good maintenance. Do you do any maintenance at all? Air filters? Plugs? Oil changes?

Hopefully, one of the big dogs who actually know something will chime in but I know enough to say a poorly maintained Lexus is a nightmare to diagnose.

brabbit

carver, I upgraded the air filter to a k & N a few months ago b4 winter... the plugs checked out ok the last time it was in and yes the oil is changed every 3500 miles... I worked hard I make 12.00 an hour so it took a lot of overtime for me to even afford a used one. Mine is a 99 rx300 it may not be new but it was new to me last year, it was a one owner- and my guess is they must have not taken all that good of care of it as I have had issues with mine. Now after this problem is fixed I have another issue.. either the left front brake is hanging up or the parking brake mechanism is hanging up-?? if the mechanism is even in this area? before this whole check engine fiassco came upon me.

bearbrew

When you installed the K&N air filter there may have been an excessive amount of oil on it. If some of this oil is drawn across and fouls the Mass Airflow Sensor (MAF) this can cause codes to be thrown.
You may want to remove the MAF sensor and clean it with some contact cleaner or the cleaner produced for use on the MAF sensor. The reset the Check Engine Light.

The parking brake mechanism is on the rear rotors. Check the front caliper for lack of lube or being seized where it moved in and out when you apply the brakes. Clean if necessary and lightly lube the moving surface with a high temp grease made for the purpose.

brabbit

thanks, I'll give your advice a try. I'll repost when I get an update

Carver

I truly meant no offense. Like the exhaust issue, the brakes can be handled by any competent shop. Your issue could be as simple as a lack of lubrication.

brabbit

ok so heres the update; I took out the MAF sensor and examined it, it appeared to be dirty so I cleaned it with the maf cleaner then reset the code and notcied a difference in the mpg, the idle was smoother, had my fingers crossed but the check engine popped up today so it was clear for about 40 miles traveled. Any suggestions? I'm going to clean it again and clear the code, I'm thinking I may need to replace the MAF sensor?

brabbit

Also I wanted to add that I haven't eliminated the rear o2 sensor or the a fuel/air ratio sensor in rear bank is what someone else suggested may be the issue. At any rate the diagnosis isn't solved.

carguy07

**********Air Fuel Sensor Bank 1 Sensor 1**********