Engine stalls when stopping

Tiny
JIMSTKN
  • MEMBER
  • 2002 FORD ESCORT
  • 0.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Starts up runs rough until you get going when you start to slow down engine stalls.
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Sunday, October 7th, 2018 AT 3:18 PM

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Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi and thanks for using 2CarPros.com.

Many things can cause an engine to stall. However, since it is running rough, my first suspect is a vacuum leak. First, here is a link that discusses reasons why an engine stalls:

https://www.2carpros.com/articles/stall-at-idle

Next, here is a link that discusses engine vacuum leaks. Read through this link and follow the test.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If you find there are no engine vacuum leaks, make sure the air filter is not plugged with dirt or debris. Next, the idle air control valve maintains engine idle speed. Here is a description of the component specific to your vehicle. Note that there are two different ones that were used. The first three attached pictures correlate with this description

______________________
Idle Air Control Valve

Nippondenso Idle Air Control (IAC) Valve Assembly

Hitachi Idle Air Control (IAC) Valve Assembly With Vent/Filter

The idle air control (IAC) valve assembly (Figure 117) and (Figure 118) controls engine idle speed and provides a dash pot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The PCM determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine rpm and increases or decreases the IAC duty cycle in order to achieve the desired rpm.

Hitachi Idle Air Control (IAC) Valve Assembly With Air-Assist Injectors

On applications with air-assisted injectors, the AC valve (Figure 119) also supplies a small amount of air into the path of the fuel injectors. The jet of air causes an increase in fuel atomization at low speed and light load conditions.

NOTE: The IAC Valve Assembly is NOT ADJUSTABLE and CANNOT BE CLEANED.

The IAC valve (part of throttle body assembly) has an internal diode on some applications. If the internal diode is measured in crossed terminal position with a digital multimeter, there will be an incorrect or negative reading. It is important that the mating component and harness connectors correctly oriented. Diagnostic procedures emphasize this importance.

The PCM uses the IAC valve assembly to control:
No touch start
Cold engine fast idle for rapid warm-up
Idle (corrects for engine load)
Stumble or stalling on deceleration (provides a dash pot function)
Over-temperature idle boost.
Air Assist to Injectors.

____________________________________

Here are the directions for removal and replacement of the IAC. The remaining pictures correlate with these directions. I am including these directions because if there are no vacuum leaks, I need you to remove the IAC and inspect it for excessive carbon build up and if it is functioning. First, here is a link that shows in general how one is replaced.

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

The following directions are specific to your vehicle.

REMOVAL
1. Disconnect the battery ground cable.
2. Disconnect the Idle Air Control (IAC) valve electrical connector.

NOTE: Manual transmission shown, automatic transmission similar.
3. Remove the bolts and the IAC valve and gasket.

INSTALLATION
1. To install, reverse the removal procedure.

CAUTION:
If scraping is necessary, make sure not to damage the idle air control valve or the throttle body gasket surfaces or drop the gasket material into the throttle body.
The idle air control valve has a sludge resistant design and must not be cleaned, or damage to the anti-sludge coating may result.

_____________________________

Let me know if this helps or if you have other questions.

Take care,
Joe
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Sunday, October 7th, 2018 AT 7:02 PM

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