Engine - Stalling/Hard Start/No Start/Rough Idle
Article No. 86-20-6
HARD COLD START - SLUDGE IN THROTTLE BODY
STALLS - DURING IDLE OR DECEL
- SLUDGE IN THROTTLE BODY
HESITATION - DURING ACCELERATION - SLUDGE IN THROTTLE BODY
FORD 1985-86 ESCORT, EXP, MUSTANG, THUNDERBIRD
LINCOLN-MERCURY 1985-86 LYNX, CAPRI, COUGAR
LIGHT TRUCK 1985-86 RANGER, BRONCO II; 1986 AEROSTAR
CALIBRATIONS: 1.6L, 1.6L Turbo, 1.9L, 2.3L OHC, 2.3L Turbo, 2.9L
Hard cold starting, stalls during idle/deceleration, idle rough/rolling or hesitation during acceleration may be caused by sludge deposits on the throttle plate and throttle body. The deposits change normal air flow through the throttle body causing the above driveability conditions. To correct this, use the following updated diagnostic/repair procedure.
NOTE: This article supersedes TSB 86-16-12 in its entirety.
1. Perform EEC IV Quick Test (Volume H), service any error codes.
2. With the engine at normal operating temperature, disconnect idle air bypass valve electrical connector and check base idle. Refer to the chart below.
Vehicle Transmission Base Idle Speed Limits
1.6L Car Refer to Engine Decal -
1.6L Turbo Car Refer to Engine Decal -
1.9L Car Refer to Engine Decal -
2.3L Turbo Car Refer to Engine Decal -
2.3L Truck Neutral 575 +/- 25 RPM
2.9L Truck Neutral 750 +/- 50 RPM
Manual Transmission
2.9L Truck Neutral 700 +/- 50 RPM
Automatic Transmission
3. Gain access to the throttle plates as follows:
For turbocharged SVO Mustangs equipped with intercoolers, remove the intercooler.
For other turbocharged engines, remove the turbocharger air discharge hose at the fuel charging assembly.
For non-turbocharged vehicles, disconnect the air cleaner outlet tube at the fuel charging assembly.
NOTE: Discoloration of the throttle body on the bore I.D. below the throttle plate is normal. The cleaning procedure is only effective where a LARGE amount of build up is present.
4. Inspect the engine side of the throttle plate and throttle body for a sludge build up.
5. If a sludge build up is present, remove the throttle body from the vehicle. Also, except for 2.3L truck, remove the idle air bypass valve from the fuel charging assembly or from the intake manifold.
CAUTION: DO NOT use the aerosol type Carburetor and Combustion Chamber Cleaner, and DO NOT use Choke Cleaner. They contain solvents which may damage the throttle shaft seals.
6. Remove the sludge deposit from the throttle body by wiping the affected area with a rag soaked with Carburetor and Combustion Chamber Cleaner (D9AZ-19579-B). For more difficult deposits, several applications of cleaner may be required.
7. Except for 2.3L truck, clean the idle air bypass valve as follows:
CAUTION: DO NOT remove the solenoid, or use a tool to move the shaft.
a. Pour the Carburetor and Combustion Chamber Cleaner into both sides of the valve.
b. Place finger tips over the holes and gently shake the idle air bypass valve.
c. Dump the cleaner out of the air bypass valve, then blow out with shop air.
8. Assemble the idle air bypass valve onto the fuel charging assembly or the intake manifold as applicable. Then install the fuel charging assembly.
9. Reset base idle speed to specification. Refer to the Shop Manual (Volume H, Section 4) for idle speed setting procedure.
PART NUMBER PART NAME CLASS
D9AZ-19579-B Carburetor and AM
Combustion Cleaner
OTHER APPLICABLE ARTICLES: Supersedes 86-16-12
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP9926A86 - 1.6L EFI, 1.6L EFI Turbo, 1.9L EFI, 2.9L EFI
TIME: 1.1 Hrs.
OPERATION: SP9926B86 - 2.3L OHC EFI, 2.3L OHC EFI Turbo
TIME: 1.2 Hrs. DLR. CODING: Basic Part No. DRIVE - Code: N9