Intermittent Engine Stall - No Codes

Definition: Engine stalls, no ECM or BCM trouble codes are set, engine will restart immediately.

^ Check for pressure during the stall. Use of a 0-100 psi fuel pressure gage is preferred. If the fuel pressure is not at least 32 psi then use Chart A-4B, DYNAMIC FUEL PRESSURE DIAGNOSIS. A-4B Dynamic Fuel Pressure Check
^ Check for foreign material on the primary and secondary throttle blades restricting air flow. Clean with top engine cleaner or equivalent.
^ Check the ISC motor throttle switch for proper operation. Enter diagnostics and cycle the throttle from open to closed several times while observing the throttle switch status light. If the status light is intermittent, check for ISC throttle switch intermittent, throttle linkage for proper operation.
^ Check for intermittent TPS. Observe the parameter ED01 during the stall. An erratic TPS reading could cause a stall due to a false acceleration enrichment (the TPS value jumps or skips to a higher value) or if the TPS reports a false high throttle angle during coast down.
^ Check for intermittent MAT or Coolant sensors. Observe ECM data parameter ED04 coolant temp. and ED05 manifold air temp. during the stall coolant temperature should not vary rapidly under steady throttle conditions. Check for proper connector mating and for intermittent wiring.
^ Check for intermittent MAP sensor. Observe ECM data parameter EDO2 during the stall. Check for MAP hose free and clear, for sensor receiving proper vacuum signal and for sensor trapping vacuum. Check MAP sensor connector and circuits for electrical intermittents.
^ Check EGR valve for binding or obstructions and for improper EGR solenoid operation. With the engine running at idle, apply and release vacuum to the EGR valve with a vacuum source. Make sure that valve will fall and seat (completely block flow of exhaust gas to intake) when vacuum is released. At key on, engine off, enter output cycling and apply a vacuum source to the EVRV. Disconnect the vacuum line to the EGR valve and apply a vacuum gage. The gage should show vacuum at the EGR hose when the solenoid is electrically de-energized and should show no vacuum when the solenoid is energized.
^ Check for intermittent injector circuit operation. See chart A-5. Chart A-5 Injector System Diagnosis
^ Observe ECM Data Parameter ED10 battery voltage. Check for erratic or low battery voltage during the stall. If found then check charging system, battery and wiring for intermittents.
^ Check for Viscous Converter Clutch (VCC) improperly applied by a grounded VCC solenoid circuit or by transmission hydraulic problems. See Transmission and Drivetrain. Transmission and Drivetrain
^ Check for 2-3 or 3-4 shift solenoids improperly applied by a grounded shift solenoid circuit.
^ Check ignition switch circuits for intermittent open to the ECM or HEI. Manipulate the key switch while driving to check for ignition switch intermittent or out of adjustment.
^ If the stall is at low fuel level or on deceleration (manual downshift, down hill coast or on braking); check fuel sending unit and fuel pump strainer in the fuel tank for proper orientation. This can be diagnosed by checking for steady fuel pressure during the stall. (Use of a 0-100 PSI fuel pressure gage is preferred.) If the fuel pressure drops on deceleration, then remove the fuel sending unit to check.
^ If the stall is on a normal closed throttle coastdown to a stop; check for minimum air setting too high (not allowing the throttle switch a to close), for TPS setting too high (reporting a false high throttle angle during coastdown), or throttle linkage to ISC gap set incorrectly (gap too small, not allowing throttle switch to close).
^ If the stall is with power steering load or transmission loading when shifted to drive or reverse; perform the switch tests associated with the loads that are causing the stall. Check for intermittent switch inputs to the ECM. Check for proper throttle linkage to ISC plunger gap setting. If the gap is too large, the ECM may not be able to command large throttle angles when required (ISC may not extend far enough to save a stall.)
^ If the stall occurs exclusively with A/C loads; check for proper operation of the A/C clutch status indicator light and for proper A/C clutch cycling. Check for high A/C head pressures that could cause high engine loads with A/C on.
^ If the stall occurs after start-up, in hot ambients or with a full fuel tank; check for EECS canister loaded with fuel and for proper EECS solenoid operation. See diagnosis chart in Chart C-3. Chart C-3 Canister Purge Diagnosis
^ If the stall occurs in cold ambient temperatures or with a cold engine, check for proper heat range spark plugs and for spark plug fouling.