SMU - SECTION 4 - REVISED CONTROLLED IDLE SPEED SPECS.. GMC Truck GMC C Pickup

REVISION: 08/31/94

THIS BULLETIN IS BEING REVISED TO CORRECT INFORMATION IN THE MINIMUM IDLE SPEED (MARK ENGINE 7.4 LITER) SECTION.

THIS SERVICE BULLETIN SUPERSEDES SERVICE MANUAL INFORMATION FOR THE CONTROLLED IDLE SPEED SPECIFICATION ON PAGE 4-3 OF THE DRIVEABILITY, EMISSIONS, AND ELECTRICAL DIAGNOSIS MANUAL. ----------------------------------------------------------------------

SUBJECT: SERVICE MANUAL UPDATE-SECTION 4-REVISED CONTROLLED IDLE SPEED SPECIFICATION

MODELS: 1994 CHEVROLET AND GMC TRUCK LIGHT DUTY TRUCKS 1994 OLDSMOBILE BRAVADA WITH GASOLINE ENGINES

**********************************************************************

1994 CONTROLLED IDLE SPEED

NOTE: ENGINE AT OPERATING TEMPERATURE 92C TO 104C (196F TO 222F)

ENGINE TRANS GEAR (1) IDLE SPEED IAC OPEN/CLOSED A=AUTOMATIC (DRIVE/NEUTRAL) (RPM) COUNTS (2) LOOP (3) M=MANUAL _____________________________________________________________________

2.2L (MFI) A DRIVE 890+25 15-40 CL S-TRK M NEUTRAL - 950+25 15-40 CL - _____________________________________________________________________

4.3L (TBI) A DRIVE 650+25 5-30 CL S/T M NEUTRAL - 700+25 5-30 CL - ______________________________________________________________________

4.3L S/T A DRIVE 625+25 5-30 CL CENTRAL MFI M NEUTRAL - PICK-UP ------- ---- -- ______________________________________________________________________

4.3L S/T A DRIVE 600+25 5-30 CL CENTRAL MFI M NEUTRAL - UTILITY 650+25 5-30 CL - ______________________________________________________________________

4.3L (TBI) A DRIVE 537+25 5-30 CL M/L M NEUTRAL - ---- -- ______________________________________________________________________

4.3L M-VAN A DRIVE 550+25 5-30 CL CENTRAL MFI M NEUTRAL - ---- -- ______________________________________________________________________

4.3L L-VAN A DRIVE 625+25 5-30 CL CENTRAL MFI M NEUTRAL - ---- -- ______________________________________________________________________

4.3L (TBI) A DRIVE 580+25 5-30 CL UNDER 8500 M NEUTRAL - C/K - TRK 650+25 5-30 CL - ______________________________________________________________________

5.0L (TBI) A DRIVE 550+25 5-30 CL C/K-TRK M NEUTRAL - 650+25 5-30 CL - ______________________________________________________________________

5.7L C/K A DRIVE 525+25 5-30 CL UNDER 8500 M NEUTRAL - 650+25 5-30 CL - ______________________________________________________________________

4.3L (TBI) A DRIVE 537+25 5-30 CL UNDER 8500 M NEUTRAL - ---- -- G-VAN ______________________________________________________________________

5.0L (TBI) A DRIVE 525+25 5-30 CL G-VAN M NEUTRAL - ---- -- ______________________________________________________________________

5.7L G-VAN A DRIVE 550+25 5-30 CL UNDER 8500 M NEUTRAL - ---- -- ______________________________________________________________________

4.3L (TBI) A DRIVE 650+25 5-30 CL OVER 8500 M NEUTRAL - ---- -- C/K/P ______________________________________________________________________

4.3L (TBI) A DRIVE 650+25 5-30 CL OVER 8500 M NEUTRAL - ---- -- G-VAN _____________________________________________________________________

5.7L C/K/P A DRIVE 550+25 5-30 CL OVER 8500 M NEUTRAL - 700+25 5-30 CL - ______________________________________________________________________

5.7L G-VAN A DRIVE 550+25 5-30 CL OVER 8500 M NEUTRAL - ---- -- ______________________________________________________________________

7.4L C/K A DRIVE 675+25 5-30 CL M NEUTRAL - 750+25 5-30 CL - ______________________________________________________________________

7.4L G-VAN A DRIVE 625+25 5-30 CL M NEUTRAL - ---- --

(1) ON MANUAL TRANSMISSION VEHICLES, THE TECH 1 WILL READ RDL IN NEUTRAL. (2) ADD 2 COUNTS FOR ENGINES WITH LESS THAN 500 MILES. ADD 2 COUNTS FOR EVERY 1,000 FEET ABOVE SEA LEVEL (4.3L AND V8). (3) LET ENGINE IDLE UNTIL PROPER FUEL CONTROL STATUS ("OPEN/CLOSED LOOP") IS REACHED.

MINIMUM IDLE SPEED (MARK ENGINE 7.4 LITER)

ENGINE TRANS GEAR (1) ENGINE SPEED OPEN/CLOSED (DRIVE/NEUTRAL) (RPM) (2) LOOP (3) ______________________________________________________________________

7.4L A DRIVE 625+25 CL M NEUTRAL - 625+25 CL -

(1) ON MANUAL TRANSMISSION VEHICLES, THE TECH 1 WILL READ RDL IN NEUTRAL. (2) IF THE ENGINE HAS LESS THAN 500 MILES OR IS CHECKED AT ALTITUDES ABOVE 1,500 FEET, THE IDLE RPM WITH A SEATED IAC VALVE SHOULD BE LOWER THAN VALUES ABOVE. (3) LET ENGINE IDLE UNTIL PROPER FUEL CONTROL STATUS (OPEN/CLOSED LOOP") IS REACHED.

FIGURES: 00 ATTACHMENTS: 00

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.