Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Engine - Hard Cold Starts/Hesitation/Stalls On Start-Up: Overview
1990 Mercury Cougar/XR7 V6-232 3.8LSECTION Overview
91ford29
Article No.
91-25-7
12/13/91
^ HARD COLD START - DURING INITIAL START-UP, IDLE OR DECEL - EFI ENGINES - SLUDGE IN THROTTLE BODY AND/OR IDLE AIR BY-PASS VALVE
^ HESITATION/STALLS - DURING INITIAL START-UP, IDLE OR DECEL - EFI ENGINES - SLUDGE IN THROTTLE BODY AND/OR IDLE AIR BY-PASS VALVE
FORD: 1983-87 EXP
1983-91 ESCORT
1984-90 MUSTANG, THUNDERBIRD
1986-90 TAURUS
1986-91 CROWN VICTORIA
1988-90 TEMPO
LINCOLN-MERCURY: 1983-85 LN7
1983-87 LYNX
1984-88 CAPRI
1984-90 COUGAR
1986-90 CONTINENTAL, MARK VII, SABLE
1986-91 GRAND MARQUIS, TOWN CAR
1988-90 TOPAZ
1991 TRACER
LIGHT TRUCK: 1985-90 BRONCO II, BRONCO
1985-91 ECONOLINE, F-150-350 SERIES
1985-92 RANGER
1986-91 AEROSTAR
1991 EXPLORER
ISSUE: Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions.
^ Hard Cold Start
^ Stall On Initial Start-Up
^ Stall During Idle
^ Stall During Decel
^ Rough Idle
^ Rolling Idle
^ Hesitation During Acceleration
ACTION: A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years.
Figure 1:
Install an idle air by-pass service kit (F2PZ-9F939-A) as applicable to provide a permanent correction for symptoms caused by throttle body sludge deposits. Refer to the instruction sheet included in the kit for installation details. Refer to Figure 1 for a specific application list of EFI (port fuel Injection) engines involved in this TSB article.
The idle air by-pass service kit (F2PZ-9F939-A) includes the following items.
^ One (1) Idle Adjust Spacer
^ Two (2) Gaskets
^ Two (2) Attaching Bolts
^ One (1) "Attention" Sticker
^ One (1) Instruction Sheet
Figure 2:
Refer to Figure 2 for a pictorial of the kits components.
NOTE: EFFECTIVE WITH THIS TSB, THROTTLE BODY CLEANING IS NO LONGER COVERED UNDER 5/50 EMISSIONS WARRANTY, UNLESS AS SPECIFIED IN THE FOLLOWING APPLICATION CHARTS. FAILURE TO FOLLOW THE CORRECT PROCEDURE MAY RESULT IN THE CLAIM BEING DISALLOWED.
The idle air adjust spacer incorporates sludge tolerant design features that eliminate throttle body sludge related conditions. Once installed, throttle body cleaning is not allowed and periodic adjustment of the throttle body is not required.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.