High revs when idle

geurrp the yard

04 corolla, revs around 1200 rpm when idle and the car seems to be eating the juice. Any suggestions to what the problem might be.

pajero12

Idler screw turned in too much?

geurrp the yard

Yeah i was thinking that, would that cause the car to be eating the petrol

Plug

The idle speed control valve, turn on a few loads, headlights, heaters etc and listen and watch the rev's.

ianobrien

pajero12 wrote: »

Idler screw turned in too much?

I thought the idle screw went out when the carburettor did. Modern Fuel injection uses an idle control valve.

OP, I'd say find your local friendly mechanic, as if it's burning that much juice you're running rich. The excess petrol down the exhaust could potentially mess with the catalytic converter.

johndaman66

Would be thinking idle control valve. Believe that cleaning/ adjusting them sometimes does the trick but quite often they will need to be replaced. Seen as your burning a lot more petrol and there is a chance of damaging your catalytic converter as another poster mentioned it would probably be in your best interest to get it taken to the garage as soon as is possible

dunsandin

+1 on idle control valve, but i'd be trying the cleaning it route before the replacing it route, use aerosol carburettor cleaner, and with the valve off, get as much of the gunk out as possible, then refit, usually works, if not, your into a newie. edit; is there a MAF on these? If that was fouled it would cause the crap economy and could elevate idle. would also give crap performance tho.

Mr Benevolent

Them's MAF failure symptoms. Get thee to a mechanic.

shayser

Sorry to resurrect this old thread but I am having the exact same problem as the OP. After reading this thread I took the car to a main dealer who told me the reason was that 4 coils needed replacing. Does that sound right? I had a good bit of work done fairly recently and this wasn't mentioned then.

dmc17

shayser wrote: »

4 coils needed replacing. Does that sound right?

Probably not as I don't think all four would go together

frasr

I had a similar issue, I found that cleaning the idle valve would solve it, but about 2 months later the same problem would occur. I got a bottle of Redex Petrol Treatment and added it to a full tank of petrol, 6 months later & there hasn't been a bother with it since.
Got the Redex in Tesco, but here's a link to halfords
http://www.halfords.ie/webapp/wcs/stores/servlet/product_storeId_11101_catalogId_15551_productId_160212_langId_-1_categoryId_212351

I've also been fussier on where I get petrol as well, as I think the carbon build ups were due to poor quality pertol

shayser

dmc17 wrote: »

Probably not as I don't think all four would go together

You know they also said front and rear bushings need replacing. The car is just out of the place after getting €1000 of work done. I can't help being suspicious.

PADRAIC.M

I see alot of these, not many know how much of an easy fix it is, but to do it right you need to remove the throttle body and then take out the idle speed control valve, it's basically a cone in a round tube that needs to spin freely, slowly rotate the shaft and you will feel where the valve is catching the housing, usual I rub the affected area first then use carb cleaner until it spins freely, then just reassemble !
Note. This is only for your high idle problem, I don't know why you were told 4 coils unless they are misfiring but that would make the car undrivable...

joujoujou

It is definately NOT ignition coil failure. If any of them fails, engine runs badly (shaking, etc) and "check engine" light appears on dash. If tried to drive, light will start blinking.

As mentioned above - clean idle control valve, clean the throttle body itself (get a set of new gaskets for it, for just couple of euros from toyota dealer), but also clean mass airflow sensor - this is located between air filter housing and throttle body (get a gasket as well, very cheap). Carburettor spray will do the job.

I'd think about 1st lambda failure, but there would be check engine light as well.

shayser

joujoujou wrote: »

It is definately NOT ignition coil failure. If any of them fails, engine runs badly (shaking, etc) and "check engine" light appears on dash. If tried to drive, light will start blinking.

As mentioned above - clean idle control valve, clean the throttle body itself (get a set of new gaskets for it, for just couple of euros from toyota dealer), but also clean mass airflow sensor - this is located between air filter housing and throttle body (get a gasket as well, very cheap). Carburettor spray will do the job.

I'd think about 1st lambda failure, but there would be check engine light as well.

The engine was shaking a bit and sounded lumpy. Will I not bother with getting the coils replaced? There is no bother starting the car and no warning light.

I think they did the cleaning bit. The revving when idle has stopped, it's nice and smooth now.

joujoujou

shayser wrote: »

[...] Will I not bother with getting the coils replaced?

Well...

One coil costs roughly 170, and you have 4 of them.

shayser wrote: »

[...]
The revving when idle has stopped, it's nice and smooth now.

So what do you worry about?

Just in case, you can provide ECU reset to set it to factory condition. 2 ways to do so:

- disconnect battery for at least 1 minute (but you will also reset radio, clock, etc),

- find the fusebox in engine compartment, remove the one marked as EFI (can also be marked as "EFI OR R/HTR" etc) for at least one minute. This will reset ECU only - all other will be safe.