Expert: Stephen Sokol - 3/25/2007

Question
Thanks for your previous answer.  I have ordered the O2 sensor and I will replace the plugs and wires this week.  The oil was recently changed with Mobil 1 5w-50.  This morning, while driving to work at 615 am, the car began with the hiccups (worst than ever) after driving only for about 5 minutes.  It eventually stalled and would not re-start. I attempted an ECU diagnosis and the check engine light would not flash at all (no codes).  I waited about 10 minutes, did and ECU diagnosis and got the 4-4-4-4 code. I immediately crnaked the engine and it fired.  I began my journey back home and, after a few minutes, the hiccups were back.  Same thing with the ECU diagnosis as before and the engine started again.  Do I have a faulty ECU?  Does the outside air temperature affect the fuel injection system? It was 65F out this  morning and I have noticed that the hiccups are less recurrent during the day when it's hot out. Help......please!!!!

Answer
For a problem like this I start with the battery and the ground connections. Clean the battery terminals and while doing that do you notice a sulfur smell--if so, replace the battery. A sulfating battery will confuse the ECU in this very manor. Now track and clean all the computer ground connections and check the engine to body ground strap.

With a DMM check battery voltage at rest--it should be 12.66 volts minimum. You will get a reading above 13 volts just after shutdown. Then read battery voltage with engine running and it should be more than 13.5 volts. Now set the DMM to a/c volts and read battery voltage which should be less than 0.350 volts.

All of these checks are necessary before condemning FI parts.