Getting Ready To Attack...iac Or Vvt Oil Valve?

94TA · February 2, 2012

**EDIT- Car is a 1999 ES300 with 173000 miles on it, currently getting 22-23 average MPG.**

About 2 days after i got my ES300 I had to replace a Oil control valve that was making the car act insane.

Right now as the car sits the issues that i get are...

-Rough idle in Drive when car is warm/running for a long time...sometimes i put it in nuetral at a light just so its happy.

- If i ever need to slam on the brakes the rough idle worsens alot and it starts to resemble what it did when it needed the oil control valve.

Ive been driving it like this for about a year! (i try not to slam on my brakes or drive it for to long)

The reason I think the other oil control valve is acting up is because I read somewhere that the engine will apply engine braking when you hit the brakes hard. This would mean the oil control valve would be used right? Same thing with the hill assistance, It senses the engine needs more power, and puts the oil control valves into the correct position.

BUT, The IAC comes to mind because I can watch my idle go from 200-300rpm lower then normal idle, back to normal idle. So in my mind maybe its just slow and needs help? It idles pretty high for awhile in the morning too. However, It has no issues starting in the morning, after its sat 4 days, in 15º weather, when the car has been running and is started soon after...most IAC issues the car will not start or it will start and die.

I want to sell this car soon, and I dont need someone on a test drive hitting the brakes hard and it acting crazy.

My check engine light was on most of the year, it would go off and come back at random, It was a EVAP code, possibly charcoal canister or VSV, Could just be the gas cap too. Its been off since I filled up last, so thats why i think gas cap. When the oil control valve was very bad it set a code for misfires.

Anyways, What would you throw your money at? Im thinking a new oil control valve for the side i didnt replace, and then taking the IAC apart and cleaning it? I guess go from there? (wish i could remember which bank oil control valve i replaced!)

lenore · February 2, 2012

I would go with the IAC cleaning, but do it completely not the short cut...Take it apart and be very careful...

lenore · February 2, 2012

here is a great procedure from the RX forums which should be same as yours...

http://us.lexusownersclub.com/forums/index.php?showtopic=7408&hl=iacv

94TA · February 2, 2012

I ordered the other Oil Control Valve last night, 173k miles...it wont hurt.

When it arrives i was planning to put it in and also clean the idle air control.

Thanks for the link, hopefully my issues will finally go away.

These last 2 weeks have been good. I finally have no CEL or TCS light on, and i can actually hit the TCS button and turn it off and on!

Lexlogic · February 3, 2012

Perhaps these links can help

Oil Control Valve

http://us.lexusownersclub.com/forums/index.php?showtopic=68046

IACV

http://us.lexusownersclub.com/forums/index.php?showtopic=30723&hl=

94TA · February 4, 2012

I took the IACV off today. The worst part was ripping one of those intake duct/sleeves that runs from the throttle body to the splitter. I thought it was going to be a nightmare but i got all the screws out without stripping any of them. I actually got to do it twice, moved the car back and found the throttle body gasket laying on the ground. So after a trip to lowes for the all mighty 2" rubber sewer hose coupler and scrubbing it with carb cleaner and an old took brush its all back together.

It seems to Idle better, i picked up a nice squeal on the serp belt side, think its from the weather, the nissan titan with 38k miles was squeaking to when i went to lowes.

The best thing so far is last night i replaced the rear sway bar bushings with a set of moogs. I could literally slide the sway bar back and forth. After doing front struts, front sway bar links and rear sway bar bushings i lost 90% of my suspension noise. I think when i do the front swap bar bushings it will be smooth as silk again.

94TA · February 23, 2012

Well Hell, My rough/low idle came back.

I have a code, i think it the VSV code. This cant cause a low/rough idle can it?

Im thinking about buying a brand new IAC now. But im not sure if its the real issue

Ive noticed that the rough/low idle, which is about 500rpm and the car hates life, happens when i fill up with gas.

Could the VSV go into purge mode, the engine richens up clearing the charcoal canister, and then it goes into a rough idle?

After cleaning my IAC i would come to a light and I could watch the RPMS slowly go from 550-650 up to the 750 mark. It still does this most of the time.

Im kind of at a loss of where to put my money.