Yaris 1999 1.0 Low Idling Speed

[Davax]

My Yaris 1999 model 1.0 which I am presently restoring has an idling speed of approx. 550rpm at normal running temperature. No accessory being turned on. When cold idling speed is higher until it reaches it normal running temperature. The thing which is bothering me is that with this slow idling when starting to move from rest on 1st gear and accelerator pressed the engine does not respond immediately. When the a/c is on or the power steering is turned fully the idling speed is increased, the engine does respond immediately. Engine oil and oil filter, air filter, and spark plugs have beeen changed. I also added injector cleaner in the fuel tank. I cleaned the trottle body with a bit of carburator cleaner (I did not remove the trottle body from engine).

Can anyone tell me if I can remove the idling control valve and clean it with carburator cleaner? Or maybe someone has an idea what I should do. What should the idling speed be for this vehicle (1SZ-FE)?

Here are the readings from my code reader scanner.

LIVE DATA

Coolant (deg F) 196

ST FTRM1 (%) ranging from -1.5 to 3.9

LT FTRM1(%) -5.4

Engine (rpm) 550

Veh speed (mph) 0

Ign Adv (Deg) ranging from 3.0 to 5.5

IAT (deg F) 126

MAF (lb/min) 0.140

ABSLT TPS (%) 10.1

O2S11 ranging from 0.075 to 0.815V 0.07 to 2.3%

O2S12 ranging from 0.710 to 0.715V N/A %

OB2 STAT EOBD

I/M STATUS

MIL status off

Misfire Monitor OK

Fuel System Monitor OK

Comp. Component OK

Datalyst Monitor OK

HTD Catalyst n/a

Evap System Mon n/a

Sec Air System n/a

A/C refrig Mon n/a

Oxygen sensor Monitor OK

Oxygen sensor HTR OK

EGR system n/a

Thanks to all.

Davax

[Kcs]

Hi, have the same problems with my 2000 1.0 gls, mine has same 550-600 rpm

on tic over, i have tried to clean idle valve with carb cleaner, although

i could not get one of the screws off ! had to take the carb off with it and

just spray were i could, made nil difference ! have had a new co2 sensor ( pre

cat ) and have also cleaned the maf with electrical cleaner, still the same ! !

so many sensors to consider, i'm just going to live with it i think ! its my run

around car so not really a problem, i did use a temp fix for this idle problem,

i ajusted the throttle body- accelerater adjuster nut to up the idle speed ! this

did work but its is only a codge fix ! i think this is common fault with this engine

on older cars.

cheers

Kcs

[Davax]

Hi, have the same problems with my 2000 1.0 gls, mine has same 550-600 rpm

on tic over, i have tried to clean idle valve with carb cleaner, although

i could not get one of the screws off ! had to take the carb off with it and

just spray were i could, made nil difference ! have had a new co2 sensor ( pre

cat ) and have also cleaned the maf with electrical cleaner, still the same ! !

so many sensors to consider, i'm just going to live with it i think ! its my run

around car so not really a problem, i did use a temp fix for this idle problem,

i ajusted the throttle body- accelerater adjuster nut to up the idle speed ! this

did work but its is only a codge fix ! i think this is common fault with this engine

on older cars.

cheers

Kcs

Thanks Kcs for your reply. Then it seems I'm not the only one with this problem. Do you know what the idling speed should be for this car? Its a 1SZ-FE 1.0lt engine. I think I will remove the idle control valve just the same and clean it. Do you think that its gasket can be reused?

Cheers

Davax

[Madasafish]

Thanks Kcs for your reply. Then it seems I'm not the only one with this problem. Do you know what the idling speed should be for this car? Its a 1SZ-FE 1.0lt engine. I think I will remove the idle control valve just the same and clean it. Do you think that its gasket can be reused?

Cheers

Davax

Haynes says replace the gasket with new.

As it is coolant and the repercussions of a leak are large, it makes sense to do so...

I'll look to see what speed son's 2001 1.0 idles at...

[Kcs]

Hi, have the same problems with my 2000 1.0 gls, mine has same 550-600 rpm

on tic over, i have tried to clean idle valve with carb cleaner, although

i could not get one of the screws off ! had to take the carb off with it and

just spray were i could, made nil difference ! have had a new co2 sensor ( pre

cat ) and have also cleaned the maf with electrical cleaner, still the same ! !

so many sensors to consider, i'm just going to live with it i think ! its my run

around car so not really a problem, i did use a temp fix for this idle problem,

i ajusted the throttle body- accelerater adjuster nut to up the idle speed ! this

did work but its is only a codge fix ! i think this is common fault with this engine

on older cars.

cheers

Kcs

Thanks Kcs for your reply. Then it seems I'm not the only one with this problem. Do you know what the idling speed should be for this car? Its a 1SZ-FE 1.0lt engine. I think I will remove the idle control valve just the same and clean it. Do you think that its gasket can be reused?

Cheers

Davax

Hi, not sure what the correct idle should be, i would say it should be at least 800 rpm !

i did buy a new gasket, but as i didn't get one of the cross head screws out, it wasn't used!

bolts or cap heads would of been a better securing method !

cheers

Kcs

[sedj]

My 1.0s circa 2000 has the same idle speed when hot or at least below 700rpm, i was a little concerned to begin with as it felt a little lumpy on idle but i have learned to live with it as it never stalls. This is on a engine that had 58k on it and now 64k still running sweet and just passed its mot with the mot inspector remarking on the omissions being spot on and if only every car that came in was one of these it would make his job so much easier as they are usually faultless.

I would say there is nothing wrong with your car, but you could as said adjust the throttle body- accelerater adjuster nut to up the idle speed which would have the desired effect without much hassle.

[Davax]

My 1.0s circa 2000 has the same idle speed when hot or at least below 700rpm, i was a little concerned to begin with as it felt a little lumpy on idle but i have learned to live with it as it never stalls. This is on a engine that had 58k on it and now 64k still running sweet and just passed its mot with the mot inspector remarking on the omissions being spot on and if only every car that came in was one of these it would make his job so much easier as they are usually faultless.

I would say there is nothing wrong with your car, but you could as said adjust the throttle body- accelerater adjuster nut to up the idle speed which would have the desired effect without much hassle.

Thanks to all who replied to my query. Just to let you know my Yaris clocked 91K and still runs very good. Just passed its MOT (which here we call VRT). Anyway I was thinking of cleaning the Idling Control valve without removing it from the trottle body. Just remove the trottle body and spray alot of Carburator Cleaner inside the 2 holes there are in its side (where there is the idling control valve). Do you think it will be cleaned or is there a chance of ruining the idling control valve?

Cheers

[arcticfire]

Hi, my idle speed (wife's 1.0 2001 Yaris) was low also, about 500rpm and near to stalling. It can be changed by adjusting a small threaded bolt and nut. 

It has to be adjusted with the engine off otherwise it won't work. It has to be fully up the temperature also, very important.

Pull out the air filter front housing and also the electrical cable which is clipped near the throttle cable to get better access. 

Using an 8mm socket and extension loosen the nut a little which will break the yellow epoxy stuff. Remove your socket and extension. 

Use an 8mm spanner on the nut from the side because you  now have to use a small allen key on the top of the bolt (similar setup as most drop links) and whilst holding the nut stationary with the spanner you can turn the bolt clockwise to increase the idle or anticlockwise to decrease the idle. 

Once you've adjusted it a little, perhaps four full turns, tighten the nut with your 8mm socket. Take care as it's only a small nut, don't risk shearing things. Switch on engine and see what the revs are. Continue to adjust if necessary.  

Once happy put the air filter and electrical cable back in place and enjoy! 

Here's some photos to help you see where the bolt is, centre of images with the yellow epoxy on it. 

Should probably epoxy it again to stop vibrations working the nut loose.