So on a hunting trip yesterday i was driving my 94 mazda B4000 on the highway when suddenty it started slowing down. I floored it but the engine would rev very slowly and slowed to about 1.2k rpm and 40 mph. Then after a minute or so it went back to normal. This happened 4 more times as i drove it home. When i got back i scanned the codes (ford obd1) 181 HEGO (HO2S) sensor fault unable to switch/lean during part throttle 185 Mass airflow sensor below normal 186 Fault in fuel injector pulse width circuit / high 189 which reads the same as 181 114 air charge temperature sensor higher or lower than expected voltage
All of these are new codes along with a 327 EGR valve position circuit below minimum voltage which has been there awhile without problem. Something interesting extra to note is when filling up i have noticed sometimes gas spills from either the tank or the filler tube.
Any and all help would be appreciated on this im looking to pressure test the fuel system soon if i can.
Unplug the MAF and see if it helps at all. Cheap easy check. Also note if the vehicle runs OK while cold and then gets erratic after it reaches operating temperature. This also indicates a sensor problem. Free checks before you start throwing parts at it.
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The fuel filter will first be noticed as it starves for gas at high rpm and wide open throttle. Back off a little and it should start going OK again.
Likely the IAT and the MAF are inside the same unit here. When the PCM decides a sensor has failed it goes into a compensatory mode to run as best it can without that sensor so you can get home (or to the nearest dealer). This is probably why it picked up and ran better.