My Niece has this 92 explorer and is having poor gas mileage, rough idle, check engine light is on. I have accessed the OBD-1 error and the only thing in it is a 33 error code. It seems to be pointing to something in the EGR does anyone have any tips they are willing to share on where to go next, possibile diagnostic path or next steps? I have checked the obvious the vacuum system seems in tact and I can't detect any leaks!
Is this a continuous memory code retrieved in the KOEO test or an on demand code retrieved during the KOER test? Either way.... the DPFE sensor is the weakest link in the chain though it is not the only part that can fail. None of the parts in your particular EGR system are overly spendy so you may opt to replacing one or two parts as a matter of convenience.
1992 PC/ED pin point test for code 33 seem to centre around the EGR valve and it's vacuum system (EVRV and hoses and such). Given the rough idle (I have no idea what you consider poor fuel economy and this is a 2 ton car), I would vote for a leaking EVRV (Egr Vacuum Regulator Valve) or carbon holding the EGR valve open...HTH
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