Engine - Rough Idle/Stall After 8 Hour Soak: Overview
Article No.98-20-7
10/12/98
^ ROUGH IDLE - AFTER STARTING WHEN ENGINE IS
ALLOWED TO SOAK A MINIMUM OF 8 HOURS -
AMBIENT TEMPERATURE BETWEEN -1 AND 21
DEGREES CELSIUS (30-70 DEGREES
FAHRENHEIT) - VEHICLES WITH 2.0L ENGINE AND
CD4E TRANSAXLE
^ STALL - AFTER STARTING WHEN ENGINE IS
ALLOWED TO SOAK A MINIMUM OF 8 HOURS -
AMBIENT TEMPERATURE BETWEEN -1 AND 21
DEGREES CELSIUS (30-70 DEGREES
FAHRENHEIT) - VEHICLES WITH 2.0L ENGINE AND
CD4E TRANSAXLE
FORD:
1995-97 CONTOUR
LINCOLN-MERCURY:
1995-97 MYSTIQUE
These TSB articles are being republished to combine their concerns and implement a revised Service Procedure.
CALIBRATION
Refer to the Recalibration Cross Reference Chart for calibration numbers.
WARNING
THIS MODIFICATION IS AUTHORIZED ONLY FOR THE LISTED ENGINE(S). PERFORMING THIS MODIFICATION ON OTHER ENGINE CALIBRATIONS IS UNAUTHORIZED AND COULD CREATE LIABILITY UNDER APPLICABLE FEDERAL OR LOCAL LAWS.
ISSUE
A stall or rough idle may occur on some vehicles after starting in ambient temperatures between -1 and 21°C (30 and 70°F) after the engine has been allowed to soak a minimum of 8 hours. This may be due to a malfunctioning Mass Air Flow (MAF) sensor or Powertrain Calibration Module (PCM) calibration. The restart is normal and the condition will not repeat until the vehicle has soaked for 6-8 hours (typically overnight). This may be caused by a lean air/fuel condition.
ACTION
Test inferred Barometric Pressure (BP) Parameter Identification Data (PID), MAF voltage at idle and Long Term Fuel Trim; if two are out-of-specification, replace the MAF sensor (1995-97 model years). Then replace the PCM (1995 model year) or reprogram PCM (1996-97 model years). Refer to the following Service Procedure for details.
PART NUMBER PART NAME
F5RZ-12B579-B Mass Air Flow (MAF) Sensor
F4RZ-12A65O-LG Powertrain Control Module (PCM) F4Rz-12A65o-vB Powertrain Control Module (PCM) F4RZ-12A650-JG Powenrain Control Module (PCM) F4RZ-12A650-WB Powertrain Control Module (PCM)
OTHER APPLICABLE ARTICLES: 97-9-8
SUPERSEDES: 98-2-4, 98-7-2
WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage And Emissions Warranty Coverage
OPERATION DESCRIPTION TIME
982007A Perform Diagnostics - 0.5 Hr.
Replace Powertrain Control
Module (PCM)
982007B Perform Diagnostics - 0.6 Hr.
Replace Mass Air Flow
(MAF) Sensor And
Powertrain Control Module
(PCM) - 1995 Only
982007C Perform Diagnostics - 0.8 Hr.
Reprogram Powertrain
Control Module (PCM) -
1996-97
982007D Perform Diagnostics - 0.8 Hr.
Reprogram Powertrain
Control Module (PCM) And
Replace Mass Air Flow
(MAF) Sensor - 1996-97
DEALER CODING
CONDITION
BASIC PART NO. CODE
IF MAF IS ALSO REPLACED -
12B579 07
RECAL 42
OASIS CODES: 602300, 603300, 607000, 607400, 608000, 608400