1991 Toyota Pickup running poor at idle

Tiny
ZL1CHEVY427
  • MEMBER
  • 1991 TOYOTA PICKUP
  • 4 CYL
  • 4WD
  • MANUAL
  • 188,000 MILES
My 1991 toyota pickup 4x4 with a 22re. It runs great when its cold but as soon as it warms up the idle starts to bounce around and starts to mis. Half the time when you take off it will spit and mis but once I get the rpms to about 1500 to 2000 rpm it runs great even with it warm. Also when I turn on the ac cold or warn it wont engage the clutch unless the rpms are about 1500 so at idle the ac does not work but driving it works great. The cooling fan is electric and its on its aftermarket but it triggers as soon as you press the ac botton thanks
Wednesday, May 13th, 2009 AT 5:42 PM

3 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
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Wednesday, May 13th, 2009 AT 5:48 PM
Tiny
ZL1CHEVY427
  • MEMBER
  • 2 POSTS
It has brand new fuel filter also its has msd coil, wires new plugs and cap and rotor.
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Wednesday, May 13th, 2009 AT 5:55 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
You need to check the rest I've mentioned and come back with some results.
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Thursday, May 14th, 2009 AT 2:41 AM

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