dmullen137

First off, thanks for any insight from anybody who chooses to chime in! I bought an '11 ES350 with 51k on it from a dealership in Orange County, CA the other day and OF COURSE, during the test drive, I felt nothing of what I'm about to describe. So there's that

And I'll preface it by stating that I religiously use Shell 91-octane gasoline and I'm just starting my 2nd tank in the new car; I'm not sure what the previous owner used -- probably Arco 87 -- who knows. I also like using the Redline SI cleaner and am running that through as we speak...

Finally to my question: The car is smooth as glass while in park or neutral. I've revved it to 3 or 4K on the tach and have heard no backfires or weird noises, but the minute I put in gear, the thing idles way low -- like 560RPM -- and when it's in park, it's at about 700RPM. It seems to be worse at night with high draw on the alternator with headlights on, etc. And when the AC is on, the problem actually goes away and it doesn't idle rough. I also think it's worth tossing into this post that on like 2 or 3 occasions, it's seemed to have difficulty starting. Cold starts in the morning seem fine. It's warm starts that seem to take a bit longer.

I've reset the ECU by disconnecting the negative battery terminal for 30 minutes and that made no difference. When I started it for the first time, it did stall after a few seconds, but it started right back up (thank God lol) but the rough idle is still there

Does anybody care to throw some thought at this? I looked for vacuum line leaks and nothing was glaringly obvious, and my mechanic seems said to maybe have Longo Lexus do an EFI service with TB cleaning -- like $160 I think.

....pictures to follow as it almost seems sacrilegious NOT posting something to look at especially after that long read!

ESh

dmullen137

Wow! So apparently this is just a feature of these cars now? An idle that makes you feel like you're in a 1979 Ford Pinto? I was thinking the brushes on the alternator, funnily enough, but you've done that! I'm taking mine to an independent Lexus mechanic in the next few days and I'll hope for the best with that. I'll keep you posted! Thanks for the response!

jagtoes

When you say "rough" idle do you mean the engine shakes or vibrates. Is there any stored codes or have you checked this. After the cold start (open Loop) goes to closed loop and the idle settles it should be around 650 +/- rpm. If the idle fails to adjust when a gear is engaged or an something with a load is turned on the 1st place I would consider is the IAC (Idle Air Control) valve or circuit. Next would be the throttle body . These 2 functions feed the ECU which adjusts their functions. Ask someone to see if there is a pre-code in the system.

dmullen137

Yeah it's just that you feel the motor while sitting at stoplights and stop signs. The moment you start rolling, the roughness subsides. When compared to my recently traded in 2006 ES330 with like 160k, you couldn't even tell the motor was running. I'm noticing, too, that when you come to a stop, the idle kind of bounces around, and settles somewhere south of 600RPM. The tach slowly comes down while coming to a stop but at like 10 or 5 mph, the idle kind of bounces around and between 1000 and 600RPM. When you come to a complete stop, the idle lowers even further and settles at about 550 or so.

I'll check for any previous codes. I do have a little BT OBDII reader so I'll let you guys know!

Thanks for your insight!

H​​​oping it's not an expensive fix!

igzy

This sounds like your alternator is not putting out enough amperage/voltage and under load the ECM bumps up the RPM to compensate, so could be the alternator regulator or clutch that's going. Try measuring the output at idle and under load and see if it is in expected range.

I would also confirm the battery that it is also holding the charge properly. If battery is going, the alternator may be working harder as well to keep up the system voltage...

Btw, without load the alternator should be producing about 10A, under heavy load it goes up to 30A+, and battery should read 13.2~14.8V.

igzy

Having read your OP and this, sounds like it vibrates under AT load only. I would also check the AT oil level. Was this car serviced at the dealer? If yes, check if they did the AT service. It is possible that the oil is low which could result in vibrations you're describing...

dmullen137

Forgive me, but by AT service, do you mean automatic transmission? Because if you do, that hasn't been touched. Is there even a way to check? I thought these had the "fill it 'til it starts coming out" type ATF filler as well as no dispstick to check.

jagtoes

Idle speed is controlled by the ECM and the IAC. Any load put on the engine is compensated to the ECM idle programmed setting in the ECM. A charging alternator or the AC turning on or the PS pressure increases are all compensated by the ECM via the IAC.
Note : my 2010 with 50K miles is rock solid as it should be at idle in any gear or when I come to a stop. Any change in idle setting is being cause by a malfunction of some sort.

igzy

Yes, there is a fill hole and check hole on the side of the AT (auto/trans) case... There is a thread here on the front page of the forum that has good instructions on how to...

igzy

IAC valve was a big issue on older GM V6 engines causing stalling and rough idle. I haven't heard of any similar concerns on the Toyota/Lexus IACVs...

ESh

jagtoes

You mean this.
https://www.bing.com/images/search?q...alve&FORM=IGRE

ESh

ESh