94 corolla high idle

[coilz347]

I recently bought a 1994 corolla dx with a 5spd manual. The car has been great and gets awesome gas mileage. I recently put a tachometer cluster in the car and now that i can see the rpm i noticed that it idles around 1200rpm.

What would cause my car to idle this high? It does it after its warmed up too

Thanks Greg

[hoanganese]

Originally Posted by coilz347

I recently bought a 1994 corolla dx with a 5spd manual. The car has been great and gets awesome gas mileage. I recently put a tachometer cluster in the car and now that i can see the rpm i noticed that it idles around 1200rpm.

What would cause my car to idle this high? It does it after its warmed up too

Thanks Greg

My car used to idle as high as yours (around >1100rpm). And thank you to this forum, I fixed the problem. Now my car idles roughly around 700-800rpm after warm-up. My suggestion to you:

Look that the temperature gauge. The needle should be in horizontal position after warm up ( this does not depend on either driving on freeway or local street, it does not depend on how fast you drive it). In another word, it should always at the middle on temperature gauge at operating temperature. Now if your temp needle is below the horizontal, you have a stuck open thermostat, and that causes your high idle problem. To fix this simply replace the thermostat. Then your idle should go back to 700-800rpm range

[coilz347]

Funny you mention the thermostat..the car's thermostat was stuck open when i first bought. Ive since put a new one in and its fine now.

I just came back from taking the throttle body off and cleaning the iac valve etc. The car still idles the same.

I then noticed that theres a threaded rod with a locknut under the throttle cable thats used to adjust the throttle. I backed the stud out abit and now it idles perfectly at 800rpm.

[fast68]

cold will idle higher than warm

TB unit may be gummed up

IAC may beed carbon cleaned from it(valve that controls idle, in the TB unit)


may be a vacuum leak in intake or at TB unit base gasket, etc

if it never idles around 700 or 750 when warmed up
normal temp when warmed up should be around 195

most thermostats open at about this temp

i would check with mechanics vacuum guage to make sure its normal vacuum reading and steady needle reading as well.

if it were my car......



good luck!!!

[Rip The E Brake]

I also added an aftermarket tach.

It idles high (1500-2000 depending on the temp) when its cold out, but once it warms up, idle resets to about 500-800.

Make sure you wired it into THIS cable on the coil -

[gold94corolla]

Yup, less than 1000 rpm is normal.

However, my temperature gauge never ever ever went to half way or even close! I just taped up all of the grille openings and put my SRI back on instead of the CAI so that the car would warm up faster now that it is cold so that I have heat lol. Now, it warms up more than before, way more than before, but it is just under half way.