Yaris has low RPM idle when up to temperature.

job seeker

Hi all,

I have noticed something the last few months. When my yaris comes up to temperature the RPM seems to drop 450/500. When cold it sits at about 1000rpm. You can also feel a slight vibration on the car, when sitting at traffic lights etc. Is there any solution to this problem?

Yaris 1.0

With 147,000 miles on the clock...



Thanks.

MarkAnthony

Would you let me know what it is if you find out? I had a similar problem in my 500 - long thread on it.

In my case it started off with the throttle body.

shietpilot

A warmed up 1.0 Yaris engine should idle at around 550 RPM. You can adjust the idle speed on that engine using a 7mm (I think) socket and an allen key. If you look near the air box, on the left side you will see the throttle cable connected to a spring loaded throttle mechanism. Underneath this mechanism is a little bolt which adjust how far the throttle is open when you're not pressing the accelerator.

Turn the engine on, loosen the lock nut using a 7mm socket and turn the bolt using an allen key and you will hear it change the RPM speed. Set it up to be around 550, for the Yaris to pass NCT it will need to be between 500 and 600 so 550 is what you want. Just make sure the engine is warm before you begin this

Here's the bolt I'm talking about:

job seeker

Hi Shietpilot, that's interesting to know. You hardly know why it has dropped that low on mine? Is it just a case of high mileage, that causes it?

shietpilot

job seeker wrote: »

Hi Shietpilot, that's interesting to know. You hardly know why it has dropped that low on mine? Is it just a case of high mileage, that causes it?

MAF sensor could be dirty although 500 is not far from 550. My Yaris failed on emissions for example and I changed the O2 sensor and the idle went up to around 950 when it warms up with the new O2 sensor. I turned it down to 550 and everything was good so not sure.

When I had the subwoofer installed I had the idle turned up to 800 because my head unit and headlights would pulse with the bass

Just turn the idle up a bit and it will be grand! The higher you go, the more fuel it will use but will idle smoother so maybe bring it up a tiny bit until it sounds better

Pipetool

Before adjusting anything try checking why it's suddenly started idling low. With rough running it could be spark plug or coil ?

shietpilot

Pipetool wrote: »

Before adjusting anything try checking why it's suddenly started idling low. With rough running it could be spark plug or coil ?

Any engine will run rough at 450 RPM

Pipetool

Yep, so why is it idling low ? I agree it will be rough at 450 RPM but I still say the rough running is the cause of the low RPM. As stated : 'You can also feel a slight vibration on the car, when sitting at traffic lights etc.'

shietpilot

Pipetool wrote: »

Yep, so why is it idling low ? I agree it will be rough at 450 RPM but I still say the rough running is the cause of the low RPM. As stated : 'You can also feel a slight vibration on the car, when sitting at traffic lights etc.'

If it was misfiring it would continue to run rough when he revs it. That's not the case here so it's obviously not a misfire.

Pipetool

Ok, so why has the car started to idle low ? this needs to be investigated first. I would bet my left ball that it's misfiring at all RPM's but the op is just noticing it at idle.

shietpilot

Pipetool wrote: »

Ok, so why has the car started to idle low ? this needs to be investigated first. I would bet my left ball that it's misfiring at all RPM's but the op is just noticing it at idle.

Fair enough. I won't offer any more suggestions having had the same car with the same issues with a low rough idle seeing as you think OP isn't noticing a misfire on a low power engine.

If it was misfiring he would be struggling to drive it, never mind complain about a bad idle.

As I said, they have a reputation for having an awfully low shaky idle and the repair manual states the normal idle for this car is 550 RPM +- 50 meaning it should be between 500 and 600. At 500 RPM this engine will be very lumpy and it will shake the car.

Instead of pulling out coilpacks and beginning to clean MAF sensors (which you could fcuk up even more) why not turn the screw half a turn and have problems solved?

Pipetool

OK the car has started to idle low - why ? Pulling the plugs out takes 10 mins - fouled plug = plug or coil. No fouled plug continue to vacuum leaks or cleaning of MAF. I'm not doubting your fix or knocking it in any way. I have a very curious nature when it comes to defects that drives me to find the reason in the first place. I think it's called OCD :-)

PADRAIC.M

Standard warm idle speed for a Yaris is 450-550 rpm, this is due to the vvti system which operates at idle allowing the timing to be adjustable by the Ecu, if it was idling any higher than this I'd be investigating a sticky ISCV

shietpilot

PADRAIC.M wrote: »

Standard warm idle speed for a Yaris is 450-550 rpm, this is due to the vvti system which operates at idle allowing the timing to be adjustable by the Ecu, if it was idling any higher than this I'd be investigating a sticky ISCV

Idling speed with manual gearbox
500 - 600 1/min

450 RPM is too low. 550 RPM is the idle and the NCT will fail the car if it's more than 10% out!

PADRAIC.M

You are correct I checked the manual here, but fixing it is not by adjusting the butterfly seating position, but by removing the ISCV on the throttle body and cleaning the spinning barrel part so it isn't catching anymore