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Geo Idle

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Car: 1995 Geo Prizm, AT, 1.8 L

Problem: With car in park, car idles at 1900 RPM until it warms up (about 5 minutes) then the idle is approximately 1000 RPM.

I'm lost as I believe the IAC and MAP are working properly and the car is pulling 22 inches of vacuum. If I cover the air bypass to the IAC in the throttle body, the car seems to run fine hot and cold. Any ideas?

Thanks.

that slightly high, check for a small vacuum leak, a throttle cable pulled too tight, or a mis adjusted throttle stop.

The throttle cable and stop are fine. Could I have a vacuum leak even though the engine has 22 inches of vacuum? If so, how would I track it down?

Thanks.

The throttle cable and stop are fine. Could I have a vacuum leak even though the engine has 22 inches of vacuum? If so, how would I track it down?

Thanks.

check the high idle valve on the firewall . lots of hoses running to it.it is adjustable with a small screwdriver.. its supposed to up your idle when the a/c is running but sometimes they get out of adjustment leak or go bad and allow the idle to rise like mine did. also these engines idle up when they are low on oil. check that too.

The throttle cable and stop are fine. Could I have a vacuum leak even though the engine has 22 inches of vacuum? If so, how would I track it down?

Thanks.

check the high idle valve on the firewall . lots of hoses running to it.it is adjustable with a small screwdriver.. its supposed to up your idle when the a/c is running but sometimes they get out of adjustment leak or go bad and allow the idle to rise like mine did. also these engines idle up when they are low on oil. check that too.

 

I have the same idle issue. It warms up and gets to 1000-1200 RPM's...I think that's too high.

The High Idle Valve is easy to spot on the firewall? Located whereabouts? Anyone adjust this? Ideas and help are appreciated.

thanks.

C

I won't ever use a Fail-Safe thermostat again. I installed one in my Prizm late last fall and it locked open in just months, on a very cold day too. I do not have any problems with my cooling system so it had to be the thermostat. After replacing it with a normal one everything is great.

Sounds like you got a defective T-Stat.....like everything, it happens.

I believe the OEM stat is fail safe...hence the cost.

Would you have preferred to fail open or closed?

I won't ever use a Fail-Safe thermostat again. I installed one in my Prizm late last fall and it locked open in just months, on a very cold day too. I do not have any problems with my cooling system so it had to be the thermostat. After replacing it with a normal one everything is great.

Sounds like you got a defective T-Stat.....like everything, it happens.

I believe the OEM stat is fail safe...hence the cost.

Would you have preferred to fail open or closed?

I won't ever use a Fail-Safe thermostat again. I installed one in my Prizm late last fall and it locked open in just months, on a very cold day too. I do not have any problems with my cooling system so it had to be the thermostat. After replacing it with a normal one everything is great.

 

I'll get to the t'stat soon. Is it a tough do-it-yourself project? It doesn't look that bad from the online "how-to" at Advance Auto.

thanks for everyone's input.

C

Sounds like you got a defective T-Stat.....like everything, it happens.

I believe the OEM stat is fail safe...hence the cost.

Would you have preferred to fail open or closed?

I won't ever use a Fail-Safe thermostat again. I installed one in my Prizm late last fall and it locked open in just months, on a very cold day too. I do not have any problems with my cooling system so it had to be the thermostat. After replacing it with a normal one everything is great.

 

I'll get to the t'stat soon. Is it a tough do-it-yourself project? It doesn't look that bad from the online "how-to" at Advance Auto.

thanks for everyone's input.

C

an hour for the whole thing with basic hand tools. a little tip is to use a glob of silicone grease to hold then new gasket in place when installing it all, makes it easier.

 

 

...........I'll answer my own question.

Had a first hand experience last night with a non-failsafe thermostat. My daughter's Camry overheated on the Mass Pike on the way home from college and she was dead in the water. The thermostat failed closed. This is a perfect example of why a failsafe style is the right choice.

A. This road is very dangerous to break down on. Thankfully it was daytime and there was a grassy hill where she stopped so she could get away from the roadway.

B. There was always the chance that she fried the engine ($4000 replacement)

C. I wouldn't have had to leave work early and drive 2 hours to rescue her.

It's just not worth the risk to not use failsafe style products. Worst case she would have been without great heat, maybe a little less fuel economy and if ignored for a considerable period of time...maybe damaged the cat.

NAPA did not have failsafe thermostats so I installed what they had and will install a failsafe tomorrow in her car as well as her sister's Camry and my wife's van.

Jay in MA

Sounds like you got a defective T-Stat.....like everything, it happens.

I believe the OEM stat is fail safe...hence the cost.

Would you have preferred to fail open or closed?

I won't ever use a Fail-Safe thermostat again. I installed one in my Prizm late last fall and it locked open in just months, on a very cold day too. I do not have any problems with my cooling system so it had to be the thermostat. After replacing it with a normal one everything is great.

Cars always idle faster when cold, as part of the warm-up process.

Get a good thermostat and change it, then the heat will work and be hot enough.

Update from a beautiful sunny day in PA:

parts, $25, labor $50, Geo purring at an idle of 700rpm's ... priceless.

The thermostat was buggy, and now the car temp is constant, and it smoothed out the idle and seems to have made it quieter.

Great heat now, too, but with 70 degree temps, the windows are down!

Glad to hear all is well.

Do you know what style T-stat they installed for you?

Jay in MA

Update from a beautiful sunny day in PA:

parts, $25, labor $50, Geo purring at an idle of 700rpm's ... priceless.

The thermostat was buggy, and now the car temp is constant, and it smoothed out the idle and seems to have made it quieter.

Great heat now, too, but with 70 degree temps, the windows are down!

Glad to hear all is well.

Do you know what style T-stat they installed for you?

Jay in MA

Update from a beautiful sunny day in PA:

parts, $25, labor $50, Geo purring at an idle of 700rpm's ... priceless.

The thermostat was buggy, and now the car temp is constant, and it smoothed out the idle and seems to have made it quieter.

Great heat now, too, but with 70 degree temps, the windows are down!

Stant Super Stat; got it from Advance Auto.

Good choice.

Stant Super Stat; got it from Advance Auto.

You may have seen my mentioning Miss Bluebell, the car I learned to drive on. When it was chilly, at least when she got old, she had higher idle.