Idle issue

[syko120]

Wsup guys,
I just bought a Lexus Sc400 off CL dirt cheap Its got 117k miles
Recently Ive been having an idle issue, it idles stupidly low around 300-400rpm. I read that the baffle on the factory intake sometime comes lose and causes this problem well mine isn't. It hasn't had this problem with a cold start up but usually when the car is at normal operating temp. I shut it off come back in like 15mins later then it starts idles down and dies on me. I have to give it some gas so it stays on.

At first I thought it was a vacuum leak but if it was wouldnt i have the problem during a cold start up?

I need a second or third opinion.

Thanks in advanced,

 

[Russ2251]

Borrow or rent a scan tool. Engine codes should eliminate the guess work.
Is check engine light lit?

 

[syko120]

Borrow or rent a scan tool. Engine codes should eliminate the guess work.
Is check engine light lit?

Nope no check engine light which is kinda wierd?

This is an old skool skill test lol

 

[Russ2251]

Engine idle speed is controlled by ECM. Therefore the need for a scan tool.
Does car pass emissions inspection?
At 117k miles, its still a baby.

 

[sexyvicta]

disconect the ecu(edit: i mean disconect the battery) for like 10 mins or something/overnight to reset er thing. Might work.


or try cleaning the idle control valve or adjust the tps maaayyybe iduno much about electronics lol?

 

[syko120]

Engine idle speed is controlled by ECM. Therefore the need for a scan tool.
Does car pass emissions inspection?
At 117k miles, its still a baby.

Yes I used the Modis scan tool at work after hours and no trouble codes at all. and the only time it actually idles that low and shuts off is when the engine is at normal operating temperature, thats why im guessing its a vacuum leak. :toetap05:

Yes it did pass inspection with no problem, and yes for a 20yr old car its still not even broken in toyota have made it to 300k miles

 

[sexyvicta]

a quick google search =

 

[sexyvicta]

 

[sexyvicta]

and this:

http://www.lexls.com/tutorials/EFI/tps.html

 

[syko120]

disconect the ecu(edit: i mean disconect the battery) for like 10 mins or something/overnight to reset er thing. Might work.


or try cleaning the idle control valve or adjust the tps maaayyybe iduno much about electronics lol?

Already reset the ecu... did nada and ill test the icv and tps in the morning i need to find a multi meter and some wiring diagrams....

 

[syko120]

you just saved me a visit to alldata haha thanks man

 

[devino246]

Nope no check engine light which is kinda wierd?

This is an old skool skill test lol

If this were an old 'skool' skill test, low idle speed would be fixed by turning a screw. This is just one of many reasons why I dislike EFI.

Has this car ever had a tune-up? Does it run fine above idle?

 

[Banditz]

SEXY is dead on right with this one.

Old school yes, you would need a flat blade screw driver for sure! LOL

And just so you guys know, even if a CEL light is not on, it can STILL show up in the ecm as PENDING codes. meaning a scan tool with the ability to show them can read and detect problems even before the car's computer's are able to set off the light. They must see the same fault a multitude of times before it's assumed to be a fault. Having a meter that can read pending codes as well will save time and frustration!

 

[syko120]

Wasnt pending any codes strangly but yes Sexy pretty much hit the nail on the head with this one it was a faulty ICV which I ended up adjust to get idle where it needs to be.

Now she purrs like a kitten now onto a brake job, then seafoam and a tune up. BTW after adjust the ICV and reseting the ecu there has been a huge increase not only in throttle response but power as well.. Again thanks to Sexy victa my hat goes off to you sir.