1999 Rx 300 Hesitation/stall

[bjoffe]

Hi all, I have read some posts about some of the newer RX models having issues with hesitation upon accelerating from a stop. I am having the same issue with my 1999 RX 300. The car has approx 115k miles, so my question is if anyone thinks this is the Fuel Pump or Filter or Sending Unit.

The Check Engine Light also was on and it read it was running lean on the back side of the engine so we replaced the O2 sensor, then on the way home the light came back on. Checked it and it was running lean on the front side of the engine now.

Has anyone else experienced these types of problems with a 1999 RX 300? Thanks in advance.

[tjmc11]

Change the fuel filter. Clean the throttle body if it hasn't been done....research in this forum before you just tear it apart...some of the screws holding it strip easily. If it is running lean it could be anything from a vacuum line being loose, a air intake hose being loose, a faulty injector, or the throttle body malfunctioning. You are basically experiencing a problem with the fuel air mixture which can be either fuel pressure realted / injector problems or from the air supply side. It could even be the EGR data causing the computer to over compensate and make the mix lean. Research lean in this forum and I'm certain you will find some extra data that can help.....let me know what it is so I can keep your issue in the vault.....

[bjoffe]

Change the fuel filter. Clean the throttle body if it hasn't been done....research in this forum before you just tear it apart...some of the screws holding it strip easily. If it is running lean it could be anything from a vacuum line being loose, a air intake hose being loose, a faulty injector, or the throttle body malfunctioning. You are basically experiencing a problem with the fuel air mixture which can be either fuel pressure realted / injector problems or from the air supply side. It could even be the EGR data causing the computer to over compensate and make the mix lean. Research lean in this forum and I'm certain you will find some extra data that can help.....let me know what it is so I can keep your issue in the vault.....

Thanks. I will try the throttle body and the fuel filter.

[lenore]

There is a vacumn line under the air box that gets disconnected sometimes. also check your flex coupling in the exhaust under the engine and make sure it isnt broken. That could lead to an false reading at the o2 sensor that is infront of the catyltic converter.

[lenore]

Read Blustu thread, next to last, this could be your problem too.

http://us.lexusownersclub.com/forums/index...showtopic=42128

[wwest]

Hi all, I have read some posts about some of the newer RX models having issues with hesitation upon accelerating from a stop. I am having the same issue with my 1999 RX 300. The car has approx 115k miles, so my question is if anyone thinks this is the Fuel Pump or Filter or Sending Unit.

The Check Engine Light also was on and it read it was running lean on the back side of the engine so we replaced the O2 sensor, then on the way home the light came back on. Checked it and it was running lean on the front side of the engine now.

Has anyone else experienced these types of problems with a 1999 RX 300? Thanks in advance.

Did you disconnect the battery in order to reset/erase the old parameters pertaining to the oxygen sensor you removed?

In any case it sounds as if the fuel pump does now have enough pumping capacity....

[bjoffe]

Thanks all, I am cleaning Throttle Body today and I will check the vaccuum line. If that doesnt work I will be changing Fuel Filter, but leaving the seat off. Then I will change the fuel pump. I just REALLY did not want to spend the $180 on a fuel pump after spending over $200 for the O2 sensor. Again, thanks to eveyone for advice I will update...