For 1990-2009 cars

# GROUP 6C - ENGINE FUEL SYSTEMS MULTIPLE SUBJECTS/MISC. ITEMS

GROUP 6C - ENGINE FUEL SYSTEMS - MISCELLANEOUS ITEMS

1. POOR COLD DRIVEABILITY - ALL GASOLINE ENGINES

1981 and 1982 Cadillacs equipped with gasoline engines may experience poor driveability after a cold start. This condition could be caused by the control damper assembly in the air cleaner remaining open forcing cold air into the carburetor or throttle body. The vacuum supply to the damper assembly, which closes the assembly during cold engine operation, may be restricted. Check for a vacuum restriction in the vacuum hose connections of the thermac sensor shown in the following illustration. The sensor nipple with the small orifice may be plugged by a soap solution used during assembly to ease hose installation. A tag wire can be used to unplug this orifice.

2. ECM MAY BE DAMAGED BY INCORRECT ISC/TPS ADJUSTMENT PROCEDURE

When performing an ISC/TPS adjustment on a DFI or DEFI-equipped vehicle, the ISC motor must not be held (stalled) in the fully retracted position for more than 4 seconds before disconnecting the ISC connector. If held for more than 4 seconds, the ECM may become overstressed, possibly resulting in the need for replacement of the ECM at later mileage.

3. 1.8L CARBURETOR ADJUSTMENT - CIMARRON

The fast idle adjustment (bench setting) procedure on page 6C1-6 of the 1982 Cimarron Service Manual does not specify in step 2 the number of turns required to adjust the fast idle screw.

Step 2 should read, turn fast idle screw in or out to just contact cam, then turn screw in (clockwise) 2 turns.

This adjustment will be required only when a new throttle body is installed on the carburetor.

4. ROUGH IDLE - 1982 V-6 EQUIPPED CADILLACS

A rough idle condition accompanied by a fixed dwell below 10 DEG could be caused by a torn carburetor base gasket.

With a dwell meter connected, engine running in closed loop, carefully spray carburetor cleaner around the base gasket. Do not allow spray to touch any other surface. If dwell meter moves toward a leaner command (towards 50 DEG), the carburetor base gasket is most likely leaking.

Before removing, check carburetor retention bolts for proper torque as a loose carburetor to gasket surface could also cause this condition.

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.