Engine - Stall After Hot Restart/Cold Start,/Decel
87chevy23Number: 88-88-6E
Section: 6E
Date: NOV., 1987
Subject: ENGINE STALL AFTER HOT RESTART/COLD
START, AND COLD ENGINE HESITATION
Model and Year: 1987 CAVALIER, CELEBRITY WITH 2.8L (VIN W) ENGINE 1987-88 BERETTA, CORSICA WITH 2.8L (VIN W) ENGINE
TO: ALL CHEVROLET DEALERS
Some 1987-88 models listed above, equipped with a 2.8L V-6 engine, may experience a cold start stall, a stall after start with a warmed-up engine or a stall during deceleration. A 5-speed manual transmission Beretta, Corsica, or Cavalier may also experience a hesitation during acceleration, primarily when the engine is cold (ambient temperatures of 40 to 70 degrees Fahrenheit). This hesitation may also be experienced during transmission gear shifts.
A repeated stall after hot restart may be caused by residue accumulating inside the throttle body bore behind the throttle plate, which limits the air flow past the throttle plate in the idle position. The hesitation concern may be due to a lean Electronic Control Module (ECM) fuel calibration. The cold start/stall may be due to a lean ECM calibration, low engine idle speeds, loss of fuel pressure, or loose electrical connections at the ignition coil and/or the mass airflow sensor.
The aforementioned customer comments may be repaired as follows:
1. Perform normal service procedures as outlined in the shop manual for the repair of engine stall or hesitation.
2. Verify that all electrical connections at the ignition coil and mass airflow sensor are secure.
NOTICE: LOOSE/POOR ELECTRICAL CONNECTIONS AT ALL SENSORS AND ECM METRI-PAK CONNECTORS CAN BE A PROBLEM ANYWHERE ON THE ENGINE. INTERMITTENT CONNECTION CAN PRODUCE STALLING.
3. Verify that there are no engine vacuum leaks at the manifold absolute pressure (MAP) sensor, positive crankcase ventilation (PCV) valve, exhaust gas recirculation (EGR), or other systems.
4. Verify that the fuel system is functioning properly and has proper fuel pressure. Reference Chevrolet Dealer Service Bulletin 87-83 (Section 6C) dated March 1987.
5. Clean the throttle body bore as specified in Chevrolet Dealer Service Bulletin 87-109R (Section 6E) dated May 1987.
6. Measure the minimum idle speed and throttle position, and adjust to specification if required (reference Chevrolet Dealer Service Bulletin 87-109 Reissue.
7. Replace the ECM MEMCAL (see Attachment A), using the following installation procedure:
(a) Disconnect battery power.
(b) Install new ECM MEMCAL calibration.
(c) Reconnect battery power.
(d) Start vehicle with AC/defroster off and power steering not cramped.
(e) Allow vehicle to idle in drive for 6 minutes and until thermostat has opened. This will facilitate learning of base idle.
(f) Return vehicle to service.
NOTICE: IT IS INAPPROPRIATE TO REPLACE THE MEMCAL AND RETURN THE VEHICLE TO THE CUSTOMER WITHOUT PROPERLY COMPLETING THE PREVIOUS SERVICE INSTRUCTIONS (ITEMS 1-6).
Use applicable labor time and operation numbers.