Posted by Neal on May 09, 03 at 01:54:46:
I have a 1991 7.4 TBI with about 70k miles on long block and 200k on truck.
After about an hour of interstate driving it started to not idle, the SES light did not come on yet.
I was able to get it started for the return trip (about 80 miles from home) and I could keep it running with the throttle, but it was "camming" real bad. Ran normal at highway speeds. After about 45 miles I finally got a SES light. when I checked that I got code 32 (Barometric Pressure (BARO) Sensor circuit failure
*OR* Exhaust Gas Recirculation (EGR) valve diagnostic switch - closed during engine startup or open when EGR flow requested by ECM
*OR* EGR / EVRV (Electronic Vacuum Regulator Valve)
AND a code 33 Mass Air Flow (MAF) Sensor - signal voltage or frequency is high during engine idle
*OR* Manifold Absolute Pressure (MAP) Sensor - signal voltage is high during idle [***Note: Engine mis-fire or unstable idle may cause this code]
The code 33 I believe was caused by the running condition, the code 32 however....since it is acting like a vacuum leak, do I need to replace the Electronic vacuum regulating valve?? If so where is it, how do I replace it etc etc etc.