Fleetwood Brougham V8-252 4.1L (1985)
PROM - Programmable Read Only Memory: All Technical Service Bulletins
Engine - 42-50 MPH Surge, Tip In Detonation, Hesitation
Bulletin No.T
86-9
File in Group
6E
Number
22
Corp. Ref. No. 805 5816-2
Date Oct. '85
SUBJECT:
REVISED SERVICE PROMS TO IMPROVE 42-50 MPH SURGE OR CHUGGLE, TIP IN OR "BURST"
DETONATION, PART THROTTLE HESITATION (FLATNESS)
MODELS AFFECTED: 1985 FLEETWOOD BROUGHAM (RWD), ELDORADO, AND SEVILLE (CALIFORNIA EMISSIONS)
The following driveability conditions may be noted in some 1985 Fleetwood Broughams, Eldorados, and Sevilles equipped with an HT4100 engine and
California emissions controls (NA6):
1.
Some vehicles may exhibit a 42-50 MPH surge or chuggle under moderate acceleration with the Torque Converter Clutch engaged.
2.
Some vehicles may exhibit a tip-in or "burst" detonation (spark knock), which may be noticed during rapid throttle angle changes, such as a wide
open throttle acceleration away from a stop. The tip-in detonation may be more prevalent at hot ambient temperatures and/or with use of regular
octane gasolines.
3.
Some vehicles may exhibit a "flatness" sensation if a light throttle acceleration manuever is performed with TCC engaged.
BEFORE installing the revised calibration to improve a chuggle or detonation condition, the following checks must be performed to verify proper basic
engine and/or fuel control system operation.
1.
Perform the DFI System Check Chart in Section 6D4, subsection A of the 1985 Seville, Eldorado and Rear Wheel Drive Brougham Service
Information Manual. Diagnose and repair any trouble codes found as well as any fuel system rich or lean indications that may be discovered using
the "Field Service Mode Check" portion of the DFI System Check chart.
2.
Use the Symptoms diagnosis in section 6D4, subsection B of the 1985 Seville, Eldorado and Rear-Wheel-Drive Brougham Service Information
Manual. The symptoms diagnosis charts that should be used are "SURGES AND/OR CHUGGLE", "DETONATION/SPARK KNOCK", and
"LACK OF POWER, SLUGGISH OR SPONGY".
The revised PROM will not repair a chuggle, detonation or flatness condition that is the result of a basic engine or fuel control system condition.
Installation of the PROM into a car with an engine or fuel control system condition will not repair a surge, chuggle, flatness or detonation -- a customer
comeback will be the likely result.
Customers may notice that the TCC does not apply as frequently with the revised PROM calibration as with the original production PROM. In addition
to changes in fuel, spark, and EGR calibrations, the new calibrations change the criteria used to apply TCC as follows:
Original Calibration
Revised Calibration
1.
Vehicle Speed greater than 43 MPH; 53 MPH;
2.
TPS reading from 6 to 23 degrees; 8 to 18 degrees;
3.
Delay before TCC is applied is 5 Secs. 15 Secs.
In summary, a vehicle equipped with the new calibration must be driven above the minimum speed and within the throttle angle limits specified for at
least 15 seconds before the TCC will apply.
PROM part numbers for 1985 Longitudinal HT4100 cars with California emissions are as follows:
Retrofit (Revised) PROM
Regular Service Replacement
Use for Surge, Flatness,
Use For Regular PROM
or Tip In Detonation
Replacement, Code 51, etc.
Broadcast
Broadcast
Service P/N
PROM I.D.
Code
Service P/N
PROM I.D.
Code
"D" CAL
1227629 *
110
DKA
16043757
28
DKA
"E" "K" CAL/MECH
1227389 **
142
DKH
1227389
142
DKH
"E" "K" CAL/DIG
1227390 **
171
DKJ
1227390
171
DKJ
NOTES: