lexway07

Hello,

i have a 99 es300 with 148k miles and recently got engine lights on with error code P0171. This also happened a year ago where i replaced the o2 sensor and the error went away only to resurface after a year.
couple months ago i observed a hissing or some similar sound while driving and when i opened the hood i could hear it somewhere close to the belt near the engine when the car was on. I wasnt sure what was causing it.but now when i turn on the car and try to listen closely i am not sure if i hear it again or if its continuously doing it..
Also when i start the car for the first stime it would die. but when i start the second time with my leg on gas raising hte accelerator the car would start fine.this happens frequently.
I have also observed a slight sound from the engine side (not sure what i should call it sounds like garr...)when i accelerate the gas after a stop sign. this goes off on a increasing speed. only happens when i put my legs on the gas after a stop or from a slow speed to increase the speed.

Anyone have any thoughts what i should be looking at ..or what could be causing these symptoms. Is there a diy steps to look at air/vacuum leaks/replace fuel filter etc? i did the o2 sensor replacement myself last time so would like to do the troubleshooting if its doable .

thanks again in advance

Lexmex

Might be your IACV valve, https://www.clublexus.com/forums/rx3...-write-up.html

lexway07

Thanks for your reply. Does this procedure apply to 99 es300 as well? the locations etc.
thanks again

Lexmex

Yes, though you'll have a single throttle body and not a dual one like mine, but it's the same procedure.

03 ES

a 99 ES has dual throttle bodies....they switched over to the VVTi 1mz with dual throttle bodies in the 99 ES...

Lexmex

You're right, I was confusing it with the baffle in front of the throttle body (which is different from the RX300). Attached one can see dual throttle bodies in a 99 ES300.