1994 Mazda B3000 Revs on Its Own

MAZDA TRUCK
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RCALZADILLA
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  • 10 POSTS
While driving, rpm at about 2500, press clutch to shift (up of down) engine stays revved up without pressing the accelerator pedal. RPMs come back down only when next gear is engaged or brake pedal is pressed hard and sudden.
Happens on and off when engine warmed up.
Gunning accelerator pedal doesn't bring down rpms.
Lubricated throttle shaft with WD40, in and out.

MAZDA B3000 1994, STANDARD TRANSMISSION
138,000 MILES.
No fault code or Check Engine lite.
Idle Air Conotrol Valve resistance good (10 ohms).
Vehicle well maintained by me since purachsed new.
Feb 9, 2007 at 5:58 AM
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MHPAUTOS
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Hi there,

This does sound strange, I had a customers car (toyota) that did this, but not as bad, i found that there was a huge build up of sticky fuel & carbon deposits behind the throttle butterfly, i used a good quality throttle body cleaner and fixed the problem, worth a try, but with out seeing this first hand, it's a sticky (no pun intended) one.

Good luck,

Mark (mhpautos)
Mar 15, 2007 at 9:52 PM
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RCALZADILLA
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Have fixed the problem:
Replaced the IAC (Idle Air Control).
raul
Mar 16, 2007 at 1:09 AM
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HELLCAT18
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I have the same problem in my '86 b2000(look at the engine siize and model number*b2000 has the 2.0* they match...) Check your oil and make sure that it's not leaking it. My engine will rev to 2 grand when sitting when it's low on oil...
Mar 29, 2007 at 11:37 PM
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SERVICE WRITER
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[quote:fd2f8027d5="HellCat18"]I have the same problem in my '86 b2000(look at the engine siize and model number*b2000 has the 2.0* they match...) Check your oil and make sure that it's not leaking it. My engine will rev to 2 grand when sitting when it's low on oil...[/quote:fd2f8027d5]


The problem was fixed.
Mar 30, 2007 at 11:22 AM

Suggested Repair

Replace the idle air control valve. Also clean carbon and fuel deposits behind the throttle butterfly with throttle-body cleaner if the throttle sticks.

Conversation Summary

A 1994 Mazda B3000 with a manual transmission intermittently stayed revved around 2500 rpm after the clutch was pressed, returning to normal only when the next gear was engaged or the brake was pressed hard. There were no fault codes, and the IAC resistance tested normal. An expert suggested cleaning sticky deposits behind the throttle butterfly. The owner later reported that replacing the IAC fixed the problem.

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