I own a 1990 Ford F-150. The truck had problems with surging idle on cold starts. After replacing a few capacitors it runs better than ever. I found my F-150…

Reid Burke

A hands-on repair guide for fixing a 1990 Ford F-150's EEC-IV engine control processor. The truck suffered from surging idle on cold starts caused by failing electrolytic capacitors inside the processor unit. The repair involves removing the processor, stripping conformal coating, replacing three aluminum electrolytic capacitors (two 47µF 16V and one 10µF upgraded to 100V), reflowing solder joints properly, cleaning leaked electrolytic fluid with IPA, and reapplying conformal coating. Diagnostics were done using the pre-OBD-II self-test method via a paperclip to read flash codes from the Check Engine light.

Repairing a Ford EEC-IV Processor for the 1990 F-150