Manual Transmission Engine Problem

This corolla is about 10-15 years old, i don’t know how old. Again, its a manual transmission. It started today, when the car idles, the engine revs up a bit like a hum. I wasn’t pressing the gas petal or anything and it just revs by it self. My dad says it was probably the engine was too cold and it is just warming itself. Then my dad said the car mechanic said its the gas sensor? what do you guys think? He also said the sensor cost about 200 and with labor job, 280$. good deal?

Sorry, but kind hard to figure out exactly what the symptoms are in your Corolla. Basically the Corolla is a good car and if $300 will fix it up it sounds like a good way to go.

UncleTurbo check out this link, same problem.
Title: idling problem

Before anyone can tell you anything you really need to improve the description. Is there a tachometer and if so, how high does it rev? Does it stay high at this point? Does the car keep running? Does the idle surge up and down or just remain high and steady? After the car is all warmed up does the idle come back down? What does it come down to?

So apparently your dad took it to a mechanic. What did the mechanic actually do? Get the very specific name for the “gas sensor” - the term “gas sensor” all by itself says nothing.

Also find out the exact model year, report the mileage on the engine along with everything you know about basic maintenance items - especially the age of spark plugs, wires, air & fuel filters.

Q: "how high does it rev? Does it stay high at this point?"
A: the engine revs but doesn’t show on the tachometer and it goes up and down, little hum like sound.

Q: "After the car is all warmed up does the idle come back down?"
A: nope we drove it for an hour or two, it was still doing the same thing.

If that was your attempt at more info I’d say that you’re still on your own.

The short story is that the most common reason for a high but surging idle is a vacuum leak.

Yeah I’d say Cigroller has it right…we are missing a lot of potential info…and the bit you gave is only confusing us. You said the rpms are not showing on the tachometer…if so…why not? DO you have a tach? if so does it work? It will be an RPM gauge prominently displayed on your dash.

My guess is what you heard from your mechanic was a reference to an OXYGEN Sensor? If so that particular sensor will not have much if any affect on your idle. It also should not be the first suspect in diagnosing your high idle problem…a VACUME leak is what you are looking for whether it be from a failed gasket…mal adjusted idle screw…or malfunctioning AIC valve. Like Cigroller said a vacume leak will make your idle high…a vacume leak will not make the idle surge however…it will be a steady high idle. Toyotas have an air idle control valve this is basically a controlled vacume leak by a valve that is temperature controlled by a sensor immersed in your coolant. Make sure your collant is topped off with no air in the system…they commonly have bleed nipples on the coolant system to help you “burp” air out of it. Have you or anyone recently added coolant for any reason? If so you may have air in your system affecting your Air idle control valves operation. Toyotas also commonly have a screw on the throttle body this screw is also a controlled vacume leak…screwing it in will lower your idle and out will raise it…see if someone monkeyed with this screw…it is commonly hidden under a rubber cap and is on top of the throttle body. Check that… first…you might be able to adjust it simply by turning that screw in some till you get a proper idle speed.


resolved how?

sold it.