2002 Mazda Tribute high idle

2002 MAZDA TRIBUTE
170,000 MILES • 3.0L • V6 • AWD • AUTOMATIC
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TRUCKDRIVERJEL
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Engine runs at high idle (approximately 2800 RPM's) it also surges when you stop at a stop sign had it hooked up on computer it shows throttle body have cleaned it real good what could be the problem
Jul 3, 2015 at 6:20 PM
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CARADIODOC
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High idle speed is the classic symptom of a vacuum leak. Start by checking the vacuum hoses for one that's broken, loose, or disconnected. You can also pinch off various rubber hoses to see if the idle speed comes down.
Jul 3, 2015 at 7:53 PM
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TRUCKDRIVERJEL
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Changed the IAC engine still runs at high idle and exhaust is getting cherry red at the manifolds vehicle appears to have straight pipe in place of catalytic converter is all this related and what's my solution
Jul 19, 2015 at 11:52 AM
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CARADIODOC
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Actually, the idle speed motor should be the last thing on the list of suspects. A red-hot exhaust manifold, (or catalytic converter) tells you that's where the fuel is burning instead of inside the cylinders where it will produce power. If the catalytic converter has been removed, the front and rear oxygen sensors are going to read exactly the same thing. The Check Engine light should be on and there should be a fault code related to "catalytic converter efficiency". Unfortunately any tests the Engine Computer performs that use oxygen sensors as a reference will be suspended, so some problems may not be detected or set a fault code to direct you to where to start.

One thing to consider is valve timing. A jumped timing belt will cause low power and late fuel injector pulses. A vacuum leak will cause high idle speed with no corresponding increase in power.

Once vacuum leaks are ruled out, have the diagnostic fault codes read and recorded. Those will indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. The people at many auto parts stores will read the codes for you for free.
Jul 20, 2015 at 8:47 PM