ancdmd

cleaned my TB thoroughly and also cleaned my MAF sensor and replaced the air filter. My transmission mount, trans fluid (full synthetic flush), spark plugs, water pump, and timing belt are all fresh, yet I get the low idle. This idle problem actually started AFTER I cleaned the TB and MAF. Engine runs silky smooth but low idle is clearly not normal. Never thrown a CEL. I do have a persistent minor leaning out/engine knock noise AND a tinny rattle/clinking noise that sounds like a loose exhaust heat shield, not sure if they're two different problems or one problem causing two different sounds under different conditions. I always use good gas and occasionally run a fuel system cleaner through the tank. Also had the y-pipe heat shields remove and the pipe inspected for leaks, none found. This issue is driving me batty.

nmikmik

yuri.ber

When your mechanic gave the "clean bill of health" did he say anything about the transmission?
If you haven't replace the tran. fluid, or it hasn't been done for a long time, i'd consider doing that. Cost of the job including new fluid is negligible compare to the cost of the new transmission.

yuri.ber

iTrader: (7)

Tranny tune up was done about 5k miles ago (tranny fluid changed and tranny filter changed).
I still got lower idle. Again CEL popped P0430 and P0430pd. I cleared the codes and it didn't pop up for 3 days already. When CEL popped out idle was ok, not low. My guess is that CEL have nothing in common with low idle.
I took out an air filter, it was clean, still I vaccumed it thoroughly. Today I will clean my TB again. If it does not help with idle I don't know what to do next

nmikmik

I'd take it to the shop again and have them check for any other possible exhaust leaks. That's for the codes. How many miles do you have on it? sorry I missed it if you have mentioned it before.
For the idle i'd check the IAC valve (i am not familiar with these cars, but it's bound to have one) and cleaned it if need be. You may try the reset suggestion from the following post to see if your MAF cleaning need a refresh in the "brain"
https://www.clublexus.com/forums/ls4...ml#post7065307

GS4_Fiend

iTrader: (22)

post up a video of your idle problem. i suspect you got a vacuum leak.

yuri.ber

iTrader: (7)

Here is a video of low idle. Took it this morning before cleaning TB.
http://s793.photobucket.com/albums/y...t=IMG_0085.mp4

After cleaning TB there was zero improvement.

GS4_Fiend

iTrader: (22)

That idle is totally normal bro. Mines does that too. The problem is the gauge is not that accurate and is sticky sometimes. I wouldn't worry about it.

As for the P0430, I would check for exhaust leaks first, make sure that post oxygen sensor is working, then suspect a bad cat. GL

yuri.ber

iTrader: (7)

Idle was never like that in almost 4 years since I owned the car. Also I can hear the the engine taking a lower note when idle is low. Anything else I can look at?

Brewmyown

Definitely check for a vacuum leak. A leak can cause a low idle for sure. My BMW 540 was having the same issue and it turned out to be a vent on the back of the plenum. It had a diaphragm in it that wore out and when the car warmed up, it would leak causing a low idle and it was sometimes throwing a code (cant remember which code). When I replace the valve, the idle was great and the problem was solved.

I had a similar issue with a Grand Cherokee I had. It was an 01 and was idling a little rough. It turned out that one of the plastic vacuum line "Tee" fitting had a crack in it. I found it by spaying the lines and the idle went up when I sprayed that area. I lifted the fitting and one of the lines broke right off. I ended up finding a cracked rubber vacuum line also. The idle was smooth but still a little low. After cleaning the IAC (Idle Air Control) it was perfect. I don't know if the LS has an IAC though.

GS4_Fiend

iTrader: (22)

Turn on the headlights and see if the idle goes higher. You can try to find a vacuum leak if you really have one but i doubt it. My car is doing the same thing. Why are you so worried about the idle? If the car is not stalling then dont worry about it.

ancdmd

Can't believe I just read that.

Brewmyown

If a car is not idling correctly there's a problem. It may be small but its still a problem. Waiting till a problem gets so bad that the car dies is not a good way to maintain a vehicle. Leaving one problem go can possibly have an adverse affect on other items.

yuri.ber

iTrader: (7)

Saga continues . After four days of no CEL it came back again. Still got a low idle. Noticed fuel economy go down. Also noticed that when the idle is low in D and I release brake pedal without pressing on accelerator the car moves very slow, like something holding its rear. Will try to go to mechanic this weekend. Those problems driving me nuts

GS4_Fiend

iTrader: (22)

Lol. If the car is not shaking its fine. If you have read my previous post, if he already cleaned the TB & MAF sensor and there is no vacuum leak, hes fine. When you put the car in drive, theres gonna be a load so of course idle is gonna be lower. To proper check idle, your suppose to check it at idle with all accessories off and in park. And he idle is fine around 600-650rpm.

yuri.ber

iTrader: (7)

Hey guys, I got a little break in the case. Since outside temp is warm/hot I started using my A/C and as soon as I turn it on idle goes normal, actually if I even turn on windshield defogger/defroster, cooled seats with A/C button on idle goes normal. Any thoughts?