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Trouble With My 2000 Rx300


mijorog
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I have owned this RX300 for a little over a year. I am the third owner. This car started out as a leased vehicle. The engine was blown while a leased vehicle and was replaced when the second owner bought it. there is 60k miles on the engine and 115k on the rest. Now to my problem.

I started my car yesterday when I put it into drive the car died. I restarted let it run for about 2 minutes then was able to drive away. When I went to lunch had the same problem waited again and worked. When I was returning to work from lunch the car wouldn't start. It would turn over want to start then die. I could get it running if I gave it gas however if I let off the gas it would die. I was able to drive with two feet to get it to my father's. (my dad is a mechanic)

We checked the fluids and everything was ok. I also had no gauge lights on while driving. When he check the codes he couldn't reset P1136. We found out it means lean fuel, however my father is not a Lexus Mechanic so all we did was check the PCV value to make sure that it worked. I cleaned it out. We are hoping someone could get us going the right direction.

I also recently had to change the Battery. That was 1 month ago.

Thanks in advance!

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Ah, the classic symptoms of the Idle Air Control Valve. Do a search on here as there are several (many highly detailed with images) DIY guides of how to clean the IACV. It doesn't need to be replaced, just cleaned (I cleaned mine with carb cleaner and an old toothbrush). It's essentially like an electronic choke, and the rotary valve gets coated in carbon and sticks. I'm 90% sure that's your problem. The other 10% is the possibility it's your MAF (mass air flow) sensor. If it is, that's an even easier fix. You can try cleaning it... in fact, cleaning the MAF would just be a good preventative. Be sure not to touch any of the sensor on the MAF, just spray it out with automotive electrical part cleaner. If you need to replace the sensor, they are roughly $100 +/- for the part.

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  • 2 weeks later...

Cleaned both IAVC and MAF sensor. Car holds an idle however it idles at 3000 RPM when I put it into gear it drops down to 1050 RPM. WHen I slow to a stop the car lurches forward when it shifts back into 1st gear.

Now I am getting P0120 Throttle Position Sensor/Switch A Circuit Malfunction. Any ideas on this one?

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  • 3 weeks later...

I had this happen to me. After I cleand my Idle Air Control valve. I cleaned the entire throttle body including that Idle Air Conrol valve again....did the trick. Both of my throttle plates were covered in carbon buildup. which I was told might have made my car have that same TPS code.

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Cleaned both IAVC and MAF sensor. Car holds an idle however it idles at 3000 RPM when I put it into gear it drops down to 1050 RPM. WHen I slow to a stop the car lurches forward when it shifts back into 1st gear.

Now I am getting P0120 Throttle Position Sensor/Switch A Circuit Malfunction. Any ideas on this one?

John has given you some good advice. I have cleaned the IACV and it worked normally afterwards, but if the throttle plates are all gunked up it could be causing the high rev. I am a FIRM believer in removing the IACV and cleaning it properly which means COMPLETELY! Some guys do a crap, half way job (on the car) and it works for a little while and then problems reappear. There is no LOGICAL reason why cleaning the IACV would cause the high rev, but anything is possible. Do as John said and look into the throttle body (with the air filter body and rubber tube off so you can see the throttle plates) and see if it looks gunked up in there. Also move the throttle cam (part the throttle cable goes on) and see if it returns nice and solidly to idle (closed throttle plates) and is not sticky. If it is messy in there, I suggest taking it off and cleaning it properly. Also recheck your work on the IACV because that IS NOT normal. Did you reinstall the little wave washer (if you took it off and apart to clean it)? Also, there is an adjustment on the IACV, although I don't think it changes things a WHOLE lot. I don't think it's possible for the IACV to cause that high an RPM under ANY circumstances so it must be the throttle plates sticking. Don't try dropping it in gear with that high RPM or you may be buying a trans.- NOT GOOD!

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