91 celica surging problem

"jim434" wrote in message

>I have a 91 toyota celica that surges from idle to about 2,000 rpm's
> constantly. I have replaced intake manifold gasket, vacuum hoses, air
> intake hose, throttle body, IAC valve, throttle position sensor,
> oxygen sensor, vacuum sensor, heat sensor, cold start valve, fuel
> injectors, fuel regulator, fuel filter, fuel pump, ECM, distributor,
> igniter, coil, timing belt, done compression check cleaned and checked
> all electrical connections, checked grounds, I dont know of anything
> else to replace, nothing helps, computer does not show any codes.
> Anyone got any ideas. Thanks :
>
>
I bet your part supplier loves having you as a customer! Sorry to tell you
this, but half of the parts you replaced have nothing to do with engine idle
speed. If those were all new parts, it would have been much cheaper to
either buy a factory repair manual, have a dealer fix the car, or buy a new
car. If the electronic parts were used, always check to make sure they are
operating properly before and after installation. The problem with just
installing a bunch of parts, especially used parts, is that the replacement
parts may be bad, or if the parts were not bad, then they were replaced
unnecessarily.

Start by checking the simple stuff first, and do not replace anything unless
it checks bad.

Check to make sure the floor mat is not interfering with the throttle pedal.
Check the throttle linkage at the throttle body to make sure it moves to the
closed position.
Check the bell crank where the throttle cable attaches to the throttle body
to make sure it closes completely.
Make sure the butterfly plate inside the throttle body closes completely.
Check the idle air control valve to make sure it moves freely.
Check the air intake hose and make sure there are no holes or cracks and
that the joints are air tight.
Check base ignition timing.
Check to make sure the AC and power steering idle up circuits are working
properly. When you turn on the AC, idle speed should increase by 100 ~ 200
RPM. The same is true when you turn the steering wheel at low speed.
Check to make sure that the voltage coming out of the coolant temperature
sensor varies with coolant temperature.
Check to make sure that the coolant comes up to operating temperature.
--

Ray O
(correct punctuation to reply)