So yesterday morning my 2007 RX350 FWD with 41K miles. Doesnt start the first time I try. Works the second time. So ok.

On the way to work it seems like it doesnt have enough power. You have to step on the gas a little more.

I get home after work and cleaning Mass Air Flow Sensor. And I go ahead and change out the engine air filter.

Today I drive around town. And you can tell its not idling right. At the red light you can see the Tach drop for a second from 800 to 600.

Its not throwing any caution lights.

And ideas before I take it back to the dealer?

 

Best guess, it is your IACV that needs cleaning.

Plenty posts in 300 forum. 330/350 should not be too different.

Salim

 

I thought about that when it first happened. My first Lexus was a 2001 RX300. And I cleaned the IACV all the time.

But I thought the RX350 had a electronic throttle by wire throttle body. And didnt have a IACV.

Does any one have a picture of one?

 

Seems to be a bit young and low mileage to be having issues with the MAF and such. What fuel octane are you running? How is it on the highway -- does it pull OK through the revs if hard on the gas?

Do you have anything you can compare against? While the low RPM is a concern, perhaps the rest may be "normal." Just throwing out ideas. Hard when you are not getting any error codes to work with. Those are the worst ones to diagnose.

Would take it by an AutoZone or Advance Auto Parts to see if they can pull any error codes as well. Just because no lights does not mean no error codes. Should be a free service.

http://www.lexuspartsnow.com/Page_Pr...gPicture=False

 

Being young and have low miles has nothing to do with the maf or the tb or anything for that matter. If you have driven in dusty conditions (includes road salt) for the first 41k miles, then it will need cleaning. If you have driven 41k miles in a "clean" location, it won't need cleaning. It's a matter of where you live.

 

How frequently did you had to clean it on the RX300? It sounds as though the environment around you isn't too clean (ie. dirt).
BTW: I'm not trying to be rude, but it does make sense. That both RX's need cleaning of the TB, IACV, etc. OR it could just be a coincidence.

 

Mine has idled around 600 rpm since I have had it for approx. 2 years.

Edit: Just looked up idle speed - 600 -700 rpm per service manual.

 

Throttle by wire adds a few more possibilities.

The engine still needs idle control and explore in there and educate us if the IACV is any different. Idle control provides the base amount of gas+air so that is why it impacts idelling and run. It is very unlikely to throw a code.

Remember when some one posts on the net, they get best guess diagnosis and often times it can be wrong. There is an advantage in gathering collective wisdom but there is lot of misinformation. Your trusted mechanic would surely do a better job.

Salim

 

Clean the IACV. Check for a vacuum line leak or disconnect. See if the idle issue is effected at all by the A/C being on or off. I would also check the PCV Valve (cheap fix) because if the blow by is malfunctioning, you will have rough idle as well.

 

I believe it does have to do with the conditions I have been are driving in. My old RX300 was on the ocean in Florida Keys. My RX350 has been in the desert since I bought it.

Today I took the black cover off the left side. And checked all the lines on the engine. To see if anything was loose. Everything looked good.

So with the last of my CRC MAF cleaner. I pulled off one of the tubes going to the intake. And sprayed the inside of engine intake down. After I go it started you could tell the difference. Idle was higher. And didn't surge sitting at the red light.

This afternoon I picked up a can of Sea Foam. And with my kid pushing on the accelerator. I sprayed the engine again. We took it out to the highway. And you could tell the difference right away. It starts on the first attempt. Doesn't surge any more. And my power was back.

Thanks again for all the help. Looks like im going to be adding cleaning my intake to my regular maintenance schedule.

Thanks for all the help. Saved me a trip to the dealer.

 

Good to hear you solved the problem!