Note On Intermittents
Display ECM parameter P.0.1. Manipulate TPS wiring and connectors. Watch for TPS valve to jump or skip. Enter output cycling and manipulate ISC wiring and connectors. Watch for ISC to stop cycling. Enter diagnostics and observe throttle switch status light. Check for binding throttle linkage or weak throttle return spring.
Verify minimum air RPM, ISC and TPS are set to specification. A Code E30 may be stored along with a Code E19. If so, see CODE E19 - SHORTED FUEL PUMP CIRCUIT. If Code E30 no longer appears after Code E19 has been corrected, do not investigate any further. The voltage on fuel pump feedback circuit made ECM improperly test Code E30.