SURGE/CHUGGLE AT 52-60 MPH INFORMATION

VEHICLES AFFECTED: 1983-1984 Deville, Fleetwood Brougham, Eldorado Seville Equipped with Federal or Altitude Emission System

Some 1983 and 1984 HT4100 vehicles equipped with Federal or altitude emissions, may experience a 84-96 KM/ph (52-60 MPH) surge or chuggle under moderate acceleration with the torque converter clutch engaged (MAP parameter .0.2 at about 85 KPA). A number of basic engine conditions in the 88 KM/PH (55 MPH) range may result from improper engine mechanical or ignition system operation. When diagnosing a Federal or altitude equipped vehicle with a surge or chuggle at (55 MPH), use the procedure listed below.

1. Perform a road test to verify that the surge or chuggle occurs under moderate load or 'crowding' (80-90 KPA MAP reading, parameter .0.2) with TCC engaged. Note engine RPM (DFI parameter .1.1) that the surge or chuggle is felt for use in step #5 below. During the road test, verify that the condition is not present with TCC disengaged. TCC may be temporarily disengaged by simutaneously depressing and holding the SET/COAST and RESUME/ACCEL switches with cruise dash switch on. On vehicles without cruise control, lightly tap and hold the brake with your left foot to disengage TCC. Care must be taken so as not to misdiagnose a vibration as an engine surge or chuggle.

2. Check and repair any DFI trouble codes.

3. Check ignition timing.

4. It may be necessary to check the scope pattern with the vehicle in drive, the brakes firmly applied, drive wheels blocked, loading the engine against the brakes to obtain a 85 KPA MPA reading in order to thoroughly inspect the ignition system.

NOTICE: Total running time during which engine is loaded against brake must not exceed 20 seconds.

CAUTION:

Brakes must be applied at all times.

A breakup on a single cylinder ignition pattern would indicate a spark plug or wire, whereas the breakup of the pattern on all cylinder indicates an engine mechanical condition, distributor, or fuel/EGR levels.

5. With the vehicle in Neutral, increase engine RPM to the value recorded during the road test in step no. 1. If the surge feel is dependent upon RPM and it is evident in Neutral, check for out of balance accessories such as water pump pulley.

6. Remove all spark plugs. Check for cracks, oil or carbon deposits, proper gap, or burned electrodes. Check condition of distributor cap rotor, and spark plug wires. If signs of oil consumption are present (i.e., oil fouled plugs), repair cause of oil consumption and replace spark plug's.

7. Check for proper EGR operation. DFI chart no. 7 (Section 8D1 in the 1983 and 1984 Service Manuals) provides a systematic diagnosis of the EGR system. In particular, the EGR circuits should be checked at the bulkhead connector since an open on either of these circuits will allow EGR at all times. These circuits are:

1984 Vehicles - Circuits 639 (cavity F5) and 435 (cavity F6) 1983 Vehicles - Circuits 639 (cavity DX) and 831 (cavity EZ)

8. On 1983 vehicles before the production breakpoints listed below, check for a restricted catalytic converter. This can be done by temporarily removing or replacing the converter. These breakpoints are:

1983 'C' B.C. No. 229508 1983 'E' B.C. No. 647667 1983 'K' B.C. No. 821885

9. Retorque intake manifold and check for leaks.

10. Road test vehicle again as described in step no. 1. Proceed to step no. 11 only if the above steps have not corrected the condition.

11. Reindex the torque converter 120 degrees.

Use most applicable Labour Operation from Canadian Labour Time Guide and claim, Federal Surge Repair, at 4.2 hours for steps 1-7 and 9-10. Add the following additional hours if steps 8 or 11 were required:

Step 8 Add .5 hour Step 11 Add .4 hour

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.