I am asking for a guy I work with who is having problems. He doesn't have internet access and I don't know (I don't own any Fords). He has a 1992 Ranger (3.0 w/standard shift). Lately his truck hasn't been running right so he had a scan done. It came up with a code 538 (insufficient RPM change during ER dynamic test) and is lost as to what to check. He has given it a complete tune up and has tried changing the Throttle position sensor. Any help on this would be greatly appreciated.

I Had The Same Problem He Should Try The Dpfe Sensor This Is Something That Only The Dealear Has And They Stock These Rangers Are Known For This Hope This Helps

Thanks for the reply. I don't want to sound stupid, but what does the Dpfe stand for. I will let him know and thanks for the help on this.

DPFE = Differential Pressure Feedback EGR sensor. I don't think Ford used them in 1992. There might be a PFE sensor on it (Pressure Feedback EGR).

Insufficient RPM change during ER test seems to indicate a problem with the idle control system.