305Busa

Hello fellow CLers. Before you ask, I did a search in the forum and couldnt find anything that was like mines. Some similar but nothing the same. Long story short, my car battery was bad and took it to get it exchanged for a new one. Car was without the battery for probably around 6 hours. Came home and installed the new battery and car fired right up but I noticed that it idles at around 400-450rpm. This is with the ac on or off. AC does not increase the RPM any. But I also noticed that at this RPM, the AC doesnt blow any cold air. As soon as I barely press the throttle and it gets to where it used to idle prior (600-700) the AC blows cold again. The car has never idled this low prior. Anyone know a DIY that will solve this issue? I took the battery out for around 2 minutes and still the same thing. Ive also read about leaving it disconnected for 30-60 min and see if it works. But before I try that and its a fail, Im wondering if anyone has experienced this and what your solution was. Thanks.

Lextrician

drive it around for a while might just need to relearn. just a suggestion, i am sure it wasnt doing it before your battery issue but i would drive for a little bit and see if that does the trick.

JiffyPop

The ECU has been reset so it must relearn all the parameters. This is very common. Should go away after 50-100 miles.

305Busa

Ok thanks. I'll try and see. Did around 20 miles since the battery change 2 days ago but I'll get at least another 30-40 tomorrow. I'll keep you posted.

aaauae

drive it for a while and it should be fine .


I always face it when i remove Battery . But after removing the Battery The car feels totally Different .

Devh

I would be concerned. As I've mentioned in another thread driving a modern car like the LS 460 without a battery can damage the electrical components including the ECU in a short amount of time. Wait and watch is probably your best approach but if it doesn't resolve itself then you have to check for damage components especially the feedback sensors.

dlbuckls10

Useful information.

Nospinzone

Yea, I think leaving the battery disconnected for 6 hours created the problem. I will probably be changing my battery before the winter. When I do, the swap will happen in minutes.

Hopefully you will be OK once you put some more miles on it.

305Busa

The car never moved without a battery. The battery was removed and the car sat the entire time.

jmcraney

Intuition tells me that you are being given some "suspect" advice. I owned an '07 LS460 for several years and disconnected the battery for extended periods on several different occasions and never a problem. The owner's manual does not give any caution, other than the need to reinitialize the TPMS, regarding disconnecting the battery. If problems were induced by disconnected batteries then the Internet and this forum would be full of reports and the cars would be hard to sell. I have been a member of this forum for about 8 years and read everything that is posted here and I assure that reports about this are rare to nonexistent. I faithfully read several other LS460 forums too - nothing there either. These are stable, reliable, well designed automobiles. As for "relearning" something, that's a myth too. These vehicle employ "intelligent transmissions" that adjust to driving habits to get the best possible gas mileage and they do that continuously. Only performance purest would notice much difference, otherwise how could multiple drivers use these cars. Just in case your car was not initialized properly when the battery was replaced, I suggest that you try disconnecting the battery for a few minutes and then reconnecting it to produce a system initialization and if that doesn't help, then seek the help of a Lexus certified technician.

JiffyPop

Disconnecting the battery again will just make the process start all over. The O2 sensors and idle control have to initialize. This is why if you bring in your vehicle for emissions testing right after a battery change they will not be able to complete the test.

http://www.justanswer.com/pontiac/2l...told-it-s.html

Keep us posted to let us know if the problem fixes itself 100 miles after your last battery disconnect.

Devh

Sorry I read your post incorrectly.
There should not be a low idle condition with a battery swap. If anything with a battery disconnected and reconnected you may get a slight bump in idle until the fuel tables settle out but it will not be dramatic.
Having an idle this low would have me suspect a bad ground connection or an alternator on its way out.
It could be the reason why the battery went bad as bad alternators will do that over time.
I would get electrical system load tested to rule out that possibility.

Lexuslsguy

Agreed. Replacing the battery and performing a soft reset should not cause a low idle condition. If anything, the opposite could be the case. A higher then normal idle is present and settles down within a short period of time. If your electrical system checks out fine, consider cleaning the throttle body. Not sure on the 460 but my 430 had a port that if clogged with carbon would affect the idle.

CRowe14

Quick question...
Due to this thread, I took note of my ide rate.
Once I start the car in the morning, of course it idles high for a few moments, but it then idles down (while letting the car warm up and before putting the car into gear).
Upon initial start up, the car idles at about 1100rpm or so.
Once the car warms/calms down. it drops to about 850-900rpm, and once I put the car in gear, it drops to about 600rpm.
Would this be considered normal?

Devh

Text book.