I have a 92 Toyota paseo, it idles a 750rpms normally, now idling around 400-500rpms, whats wrong?

Question

i have a new o2 senser, and the light is not on

Answer 1

Common causes for low idle:

1. Clogged fuel injectors
2. Clogged Fuel filter.
3. Not having proper pressure in fuel lines due to worn fuel pump.
4. Dirty or sticking throttle body

Answer 2

If it isn't stalling when you put it in gear, that sounds about right. In gear, my car idles about 500 rpm normally, once it reaches operating temperature. Have you had the battery disconnected? That mucks up the computer sometimes and it can take a short while to reset.
Every car I have ever owned has idled somewhere around that mark. The older cars with carburetors that I could adjust, I used to set the neutral idling as low as it would stay running, around 400. Unless you are absolutely sure your car is supposed to idle at 750 for some reason, and it is running poorly or using a lot of gas, I would not touch anything.

Answer 3

It could be many things. The car could need a simple tune-up. It could also need an O2 sensor replaced. If your "Service Engine" light is on, there is a good chance that it is the O2 sensor. When your sensor goes out, the CPU has problems establishing the correct idle speed.

Answer 4

Even 900 is somewhat severe, would desire to be 650 to 800! EFI Engine? IAC (Idle Air administration) Valve desires cleansing and Adjustment, Throttle Linkage desires to be wiped clean, Lubed & Adjusted. verify complete equipment for Vacuum Leaks.

Answer 5

if the a/c is on it may idle lower, but it should kick up the idle on its own unless it is not working right. it could be a clogged air filter. or a small vacuum line has a hole in it. see if you can check this stuff and get back to us. good luck!

Answer 6

umm could be a cylinder misfiring? or a spark plug?

Answer 7

something is wrong! :)