This is probably my first post in the Hybrid Rx section. I usually hang out more in the ISF section. With that being said, let me apologize before hand if this issue is a repost but after a search function, I came up with nothing. This past weekend I drove my wife's 08 Rx400 and upon starting it in the morning I realized there was a noticeable rattling noise coming somewhere from the exhaust piping area. Has anyone experienced similar issues with these cars or could it be that something is starting to fail? The car has ~33K miles and we are the original owners. Sorry for such a vague description but once the car warms up the noise dissipates. TIA

 

It's probably a loose or bent heat shield. Get under there and knock on it with you fist. My guess would be the shield that protects the spare tire from the muffler.

 

The noise tends to get louder when putting the car in gear.

 

hi.. do you mean the first time in the morning when the engine kicks on?

our 2006 has been doing that since day 1. It only lasts say for the first 30 seconds.. so we really don't put too much thought into it..

 

Rattling - either exhaust shield or more likely (and this goes for you too, joedaddy1) you need to do the ISC reset., which may signifcantly reduce the noise, if it doesn't remove it entirely.

http://us.lexusownersclub.com/forums...howtopic=58930

Read the TSB..these are the important parts...

"When the 12–volt battery is disconnected or is depleted below 7 volts on 2006 model
year RX 400h vehicles, it is necessary to perform the ISC Learning procedure to
re–initialize the idle speed control."

"It is important to perform the ISC Learning procedure anytime the 12–volt battery is
disconnected or the voltage falls below 7 volts. This procedure allows the I.C. (internal
combustion) Engine to re–learn its optimal idle speed during the initial engine warm–up
cycle or charging the HV battery. If this procedure is NOT performed, the following
customer complaints may occur:
Engine runs too long or more frequently than normal
Reduced fuel economy
Transmission gear “clatter” noise at idle is more pronounced"

This TSB says for 2006 models, because it came out in 2006. However, I've since found newer ones for 2007 and 2008. So it applies to all years of the RX400h.

You can either have the dealer do it, or follow the DIY instructions in my post from the other site.

More importantly than the rattling noise, is the increase in fuel economy that 'almost' everyone that has done the ISC reset has seen.

 

^^ you know.. i've done the ISC reset twice.. but how do i know it worked? lol.. there's no light or anything that tells me it worked..

 

Please delete this post, I intended to post to a different thread. Sorry!

 

If you happen to have an Autel Scan tool (I used a late model Maxisys), there are ISC learn status and value parameters. After you finish the 30 seconds of throttle+brake step and shut down/restart, the ISC learn value begins to change and when the ICE shuts down the ISC learn status should change from incomplete to complete. You could probably do the same with the Techstream tool, which is Toyota/Lexus specific and a bit more difficult to use, but much cheaper (I haven't tried though and don't personally own a Techstream, although I may buy one in the future (Autel can't do key coding on this vehicle!).