Toyota Trucks: Cold Start Idle Problem

My 89 Toyota Corolla AllTrac Wagon with the 1.8L 4A-FE has been doing
the same thing for a year now but I have not had any clue what is
causing it. I'm looking forward to the responses, too.

On Wed, 25 Feb 2004 12:12:19 -0600, "M22" <com>
wrote:
 

I had the same problem with my '89n 22RE, it turned out to be the
thermostat wasn't functioning properly. I remember distincly.
Replace the thermostat, make sure your hoses are good, and fill the
radiator and report back!!

Dave

"M22" <com> wrote in message news:<talkaboutautos.com>... 
starting the truck in cold weather, after about 3-5 minutes the idle
starts fluctuating by about 300-500 RPM's up and down at regular 1-2
second intervals. It is almost as if someone is depressing the
accelerator and then letting off. It does this until the truck has
been running for about twenty minutes and then it runs fine. Please
advise, thanks.

1-2 second intervals sounds kinda frequent, but it could just be the
fan turning on. i believe the 94's were still running 22re's. in my
'89 22re, i notice a definite change in idle speed (500 vs 800)
depending on whether the fan clutch is engaged or not. of course this
is more like on a 1-2 minute interval rather than a 1-2 second, but
maybe the fan clutch is bad or something.

you may also want to clean out the throttle body. i had a problem
with a very high high-idle and a very low low-idle a couple of months
ago. a simple cleaning of the throttle body brought everything back
to normal.

mike

I replaced the thermostat and the problem remains. Do you know what role the throttle body plays with the coolant? thanks for your suggestions, -Miles

I removed the air intake hose to the intake manifold and sprayed the throttle plate. Needless to say it was pretty gunked up. I'm sure this helped but it did not cure my problem. Are there any other areas of the throttle body I can clean easily?. Several questions arise, could the EGR valve need replacement? and could there be a problem with coolant circulating in the system/throttle body? Thanks for your suggestions so far, -Miles

Throttle Position Sensor most likely


"M22" <com> wrote in message
news:talkaboutautos.com... 
starting the truck in cold weather, after about 3-5 minutes the idle starts
fluctuating by about 300-500 RPM's up and down at regular 1-2 second
intervals. It is almost as if someone is depressing the accelerator and then
letting off. It does this until the truck has been running for about twenty
minutes and then it runs fine. Please advise, thanks. 

I highly doubt it's the Throttle Position Sensor or EGR, the EGR kicks
in at crusing speeds, and if the TPS was bad it would run extremely
lean. Just replace the thermostat like I said. I bet that would do
it.

Dave

I replaced the thermostat this past weekend. I replaced it with a NAPA thermostat. This did not solve the problem. I am thinking that it is something related to the cooling system also. Today after I started it up in 50 degree weather I did not expect it to idle high as though it was a 20 degree day. Do you know anything about the two stage thermostats available? Would one help? I replaced mine with the original style (one stage). Also I think the heater is playing games cold air to suddenly hot air when the heater is on, not the gradual warming I would expect. The air gets hotter as I accelerate. Let me know your thoughts, thanks -Miles