SURGE/CHUGGLE AT 52-60 MPH INFORMATION. Cadillac Fleetwood 1983

MODELS AFFECTED: 1983-1984 DEVILLE, FLEETWOOD BROUGHAM, ELDORADO AND SEVILLE (FEDERAL AND CALIFORNIA EMISSION SYSTEMS)

This bulletin supersedes Serviceman Bulletins T84-54 and T84-55, Group 6C, which should be destroyed.

Some 1983 and 1984 HT4100 equipped vehicles may experience a 52-60 MPH surge or chuggle under moderate acceleration with the Torque Converter Clutch engaged (MAP parameter .0.2 at about 85-90 kPa). A service PROM is available through GMWDD as a field fix for 1983 and 1984 HT4100 equipped vehicles with Federal emission systems. A production change consisting of a recalibrated PROM was made in March of 1984 for 1984 Devilles and Fleetwood Broughams equipped with California emission systems. In addition, service PROM's were made avanable through GMWDD for use in 1983 and 1984 Eldorados, Sevilles, Devilles and Fleetwood Broughams equipped with California emission systems. These service PROM's should only be utilized in cases where it has been determined that the condition is not caused by engine mechanical or ignition systems.

Since a number of basic engine conditions can cause similar symptoms in the 55 MPH range, the cause of the symptoms must be corrected to assure proper operation of the vehicle under all conditions. Therefore, all additional performance or reduced power comments should be repaired using the "Symptom" diagnosis as provided in Section 6D4 (Subsection A and B) of the 1985 Seville, Eldorado and RWD Fleetwood Brougham Service Information Manual before using the procedure 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) during which 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 simultaneously depressing and holding the SET/COAST and RESUME/ACCEL switches with the 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. If the condition is still present with TCC disengaged, a service PROM will not correct the condition.

2. Check and repair any DFI trouble codes.

3. Check ignition timing.

4. Check ignition per Serviceman Bulletin 83-25, Group 6D (January, 1983). 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 M AP reading of 85 kPa on Federal cars or 90 kPa on California cars 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 cylinders indicates an engine mechanical condition, distributor, or fuel/EGR levels (which are affected by the PROM calibration).

5. With the vehicle in Neutral, increase engine RPM to the value recorded during the road test in step #1. If the surge feel is dependent upon RPM and 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 plugs.

7. Check for a silicone contaminated exhaust oxygen sensor, which may be noticed as a "lazy" sensor whose response time is slower as a result of the contamination. This contamination could also be identified by removing the oxygen sensor from the exhaust manifold. The silicone deposits would appear white in color and vary in physical size. If the oxygen sensor is removed, a special anti-seize compound (P/N 5613695 or equivalent) must be used on the oxygen sensor threads before reinstalling the sensor.

8. Check for proper EGR operation. DFI chart #7 (Section 8D1 in the 1983 and 1984 Service Information 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)

9. On 1983 vehicles before the production breakpoints listed below, check for a restricted catalytic converter. Use the backpressure measurement procedure outlined in Bulletin 85-35, Group 6C, "Poor Performance and/or Reduction in Power." These breakpoints are:

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

10. Retorque intake manifold and check for leaks.

11. Road test vehicle again as described in step #1. Proceed to step #12 only if the above steps have not corrected the condition.

12. Check PROM I.D. (DFI parameter .1.3). If the PROM I.D. matches that listed below, proceed immediately to step #13. If the vehicle does not have the recommended PROM I.D.listed on the following page, replace the PROM with the indicated service part. PROM I.D. SERVICE BROADCAST (PARAMETER P/N CODE .1.3)

1983 C Federal 1227321 CTK 100 1983 C California 1226834 CTL 26 1983 E/K Federal With Mechanical I.P. 1227157 CTN 132 1983 E/K Federal With Digital I.P. 1227158 CTS 162 1983-1984 E/K California With Mechanical I.P. 1226835 CTP 57 1983-1984 E/K California With Digital I.P. 1226836 CTT 87 1984 DM/DW Federal 1227322* DMW 101 1984 DM/DW California 16042787 DRD 26 1984 E/K Federal With Mechanical I.P. 1227323*1 DMY 133 1984 E/K Federal With Digital I.P. 1227324*1 DMX 163 1984 E Federal Convertible 1227325* DMA 134 1984 E Federal Convertible With Digital I.P. 1227326* DMB 164

*NOTE ON 1984 FEDERAL EMISSION SYSTEM PROM'S:

A 1985 style PROM device was used for the 1984 Federal PROM's. Before installing the PROM's noted with an asterisk (*), perform the following additional check:

A. Check the ECM label for service part number. If the service number is 1226930, go to step C.

B. If the ECM label service part number is 1226028, check the ECM side rail number, record the first three (3) digits. The ECM side rail number is a 15-digit number with a bar code above it; refer to Serviceman Bulletin 83-86 (Group 6C), Figure 1, for an illustration of an ECM side rail number. The first three (3) side rail number digits will be "609", "082" or "209".

1. If the side rail number begins with "209", go to step C.

2. If the ECM side rail number begins with "609" or"082",replace the ECM with service part number 1226930. On the yellow "Dealer Core Information Tag" for the ECM removed, write the following as "Dealer Technician's Findings":

REMOVED PER SMB I-84-55A, 84 FED SURGE REPAIR.

C. Install the appropriate PROM using the procedure found in 1984 Cadillac Service Information Section 6D3.

NOTE ON 1984 E/K FEDERAL PROM'S:

Before installing PROM's, see Bulletin 85-10, filed in Group 6C. Follow "PROM Replacement" chart. Make sure that P/N 17084704 EGR valve is used with the surge PROM's.

If steps 1-12 have not corrected the condition, perform the following additional step:

13. Reindex the torque converter 120 degrees.

For warranty purposes, use labor Operation No. T6092, HT4100 Surge Repair, at 4.2 hours for steps 1-8 and 10-11. Add the following additional hours if steps 9, 12 and/or 13 were required:

Step 9 - Add .4 Hours (1983 vehicles before breakpoint) Step 12 - Add .4 Hours Step 13 - Add .4 Hours

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.