'92 Mazda Protege Bucks - MAS air sensor foolery

From today’s show, Stephna’s problem sounds identical to a problem I had on my '88 Toyota van.

The car would buck when trying to start, especially on a hill - sometime you could accelerate through, but mostly it would result in even more violent bucking. We had this problem for years…

Turns out it was a cracked air intake hose. This resulted in air being sucked around the MAS, confusing the computer. A $100 part (maybe overcharged) and it was 100% fixed.

Maybe test the clutch independently (try to start in 5th gear against a post/wall), or pay attention to the RPMs when this occurs. If the engine doesn’t spin free with the clutch out its prob not you problem.


Call 7: Stephna, San Francisco, CA

1992 Mazda Protege

clutch/gears/transmission question. Her car bucks and lurches in 1st and 2nd gear–can only make it stop by stepping all the way down on clutch, or shifting to higher gear. Clutch is chattring and likely cooked–she just moved to San Francisco, and may have caused it. She’d probably be better off with an automatic. Put a new clutch in this one, take it back to where she moved from and sell it there.

I had this problem on my '97 protege and it was in fact a crack in the air intake duct between the air filter box and the throttle body. The engine would rotate back in the motor mounts and pull the crack open under acceleration. Since the airflow sensor is in the air filter box, the computer would not sense any airflow and would shut off the fuel injectors. This would cause the engine to rotate forward, which would close the crack and restore the air flow through the sensor, which would cause the computer to turn the fuel back on, which would cause the engine to rotate back again, and so on. It only happened in low gear because the hamsters that turn the flywheel can’t generate enough torque to rotate the engine without the multiplication factor provided by the low gear ratio. The air duct cost me about $20 to replace, but I must confess I drove around for about a month with duct tape over the crack before I got around to changing it.