Ford Mustang:

Cold Start

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# 1  12/1/2011 2:56 AM

L. Thrower
New member
Registered: 12/1/2011
Posts: 2

Cold Start

1989 Ford Mustang GT 302 V8
The problem I'm having when starting my car in the morning. The engine won't idle properly and then it shut's off.

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# 2  12/1/2011 1:09 PM

TechHelp2
Administrator
Registered: 11/24/2009
Posts: 1299

Re: Cold Start

Two things can cause this kind of problem. The first is a bad coolant temperature sensor. If it is giving a wrong signal to the computer it can cause hard start conditions and stalling when cold. This can be checked with a computer scanner.

The second most common problem is sludge built around the throttle plate and idle air bypass valve. This can usually be cleaned out with a recommended throttle plate cleaner and a rag.

There is a service bulletin on this condition; I have listed it below. If you want the full service bulletin you can get it at ALLDATAdiy.com.

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.

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

The idle air adjust spacer incorporates sludge tolerant design features that eliminate throttle body sludge related conditions.


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