Auto Repair Q&A



Cooling System










Auto Repair Products

2001 Mazda Tribute, just serviced w. oil change & filters. When engine is cold, it sometimes starts, then stalls. Intermittent. If rev engine instead of letting it die and let it warm up, it seems fine. I can turn it off & it will start no problem.

1. Verify that it is not a

1. Verify that it is not a lean running concern by metering in propane into the Mass Airflow Sensor (MAF), to see if the engine likes additional fuel, or unplug the sensor and recheck. 2. If it likes additional fuel, check the engine for vacuum leaks, particularly the PCV vacuum hose. 3. Check the Barometer (BARO) reading on a scan tool for a contaminated/out of range MAF sensor. 4. If okay, check the Idle Air Control Valve (IAC) % on a scan tool to see if the PCM is commanding the IAC open. The higher the percentage, the faster the idle should be. 5. Check Key On Engine Off (KOEO) and KOER Differential Pressure Feedback EGR (DPFE) sensor voltage, to verify that the Exhaust Gas Recirculation (EGR) valve is not stuck open. If the DPFE voltage increases when the engine is started, the EGR valve is stuck open. 6. Test the Idle Air Control (IAC) solenoid function when cold. Try tapping on the IAC with a screwdriver handle to see if it is stuck. To test the Idle Air Control (IAC) solenoid, backprobe the WT/LB wire at the solenoid with a jumper wire. Using an assistant, start the engine and hold the throttle at 800-1000 RPM so that it will stay running. Ground the other end of the jumper wire and the engine RPM should flair to around 2000-2500 if the IAC solenoid is okay. BARO at sea level should read 152-159 Hz.

You guys are awesome! I have

You guys are awesome! I have been having a related intermittent problem for a couple of months and I took it to a dealership for service, and they couldn't diagnose it (!) I had a friend who fixes cars replace the air intake manifold gasket and--problem solved! He also replaced my spark plugs and air filter. The gasket kit was $10.99 + tax at AutoZone and my friend only charged me $50 for about 2 hours' labor. Thanks a bunch for the info.