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1990 Toyota Corolla Idling rev

Tiny
JACKOLSON
  • MEMBER
  • 1990 TOYOTA COROLLA
  • 4 CYL
  • FWD
  • MANUAL
  • 80,000 MILES
Hi Guys,

When I start my engine from an overnight parking, the engine will set at 500rpm idling rev. Then after 15 minutes it will rise to 700rpm. Or I have to rev it at a constant 1000rpm for 2 minutes then it will finally settle at 800rpm. I have a 4AFC carb engine.

Is this normal? I know it's because of the car not in it's working temperature yet, but is this okay? If it's not, how can I maintain the idling rev at normal even at start up?

Thanks and more power.
Jack
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Tuesday, June 30th, 2009 AT 4:04 AM

3 Replies

Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
No it should idle higher when cold, then settle down after a few minutes.

Try a can or two of SeaFoam and see if it helps, if not the carb will have to be cleaned and possibly rebuilt.
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Tuesday, June 30th, 2009 AT 8:00 AM
Tiny
JACKOLSON
  • MEMBER
  • 67 POSTS
Wow, this is a shock to me, thanks for this info. I always thought of it the other way around.

What is SeaFoam?

I'll try to clean the Carb first. Would it help if I use Carb cleaner sprays first? But if rebuild is inevitable then I would.

What's the recommended idling rev?

One more thing, when I turn the AC on, the idling rev decreases about 200rpm, when I turn the AC off, the idling rev goes back to 800rpm. Is this okay?

You're a great help, many thanks and more power.
Jack
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Tuesday, June 30th, 2009 AT 9:51 AM
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
Seafoam is a cleaner that you add to gasoline, it will clean varnish in fuel system.

The idle should go up when the AC is commanded, in FI cars the IAC will control this, in carb cars there is a solenoid that will increase idle speed under a load.

Idle speed is around 800 rpm.
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Wednesday, July 1st, 2009 AT 6:52 AM

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