Car hesitates and almost stalls when coming to a stop

JORDANNGIAU

MEMBER
2004 TOYOTA ECHO
1.3L
4 CYL
2WD
AUTOMATIC
193,000 MILES

When I was slowing down to a stop coming, the engines runs roughly and hesitates roughly, almost stalling but goes back to normal when I give it some gas.

Had happened to me the second time already, both when the engine is already running for some time and when I am on the road.

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

This can be several things. If you haven't already, have the computer scanned to see if there are diagnostic trouble codes. Here is a link that shows how it is done:

https://youtu.be/InIlnsjOVFA

Next, it could be related to an engine vacuum leak or the idle air control valve. Here is a link that shows how it's done:

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

If there are no links and no trouble codes, then it could be an issue related to the idle air control valve (IAC). It is responsible for maintaining engine idle speed. This part is mounted on the throttle body.

____________________________________________

Here are directions specific to your vehicle to testing or replacing the IAC. The attached pics correlate with the directions.
___________________________________________

2004 Toyota Echo L4-1.5L (1NZ-FE)
Procedures
Vehicle Powertrain Management Fuel Delivery and Air Induction Idle Speed/Throttle Actuator - Electronic Service and Repair Procedures
PROCEDURES
REMOVAL

pic 1

1. REMOVE THROTTLE BODY
2. REMOVE IAC VALVE
Remove the 3 screws, IAC valve and gasket.

INSTALLATION

Installation is performed in the reverse order of removal.

HINT: Install the IAC valve with a new gasket.

INSPECTION

INSPECT IAC VALVE OPERATION

pic 2

a. Check that the IAC valve is half open.
b. Connect the IAC valve connector to the IAC valve.
c. Disconnect the ECT sensor connector from the ECT sensor.
d. Turn the ignition switch ON.
e. Check that the IAC valve moves.

HINT: Repeat connecting and disconnecting of IAC valve connector several times and check the operation of the valve.

If operation is not as specified, replace the IAC valve.

f. Turn the ignition switch OFF.
g. Connect the ECT sensor connector to the ECT sensor.
h. Disconnect the IAC valve connector from the IAC valve.

_______________________

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

Joe

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Saturday, October 31st, 2020 AT 7:07 PM

JORDANNGIAU

MEMBER
34 POSTS

Thank you for the info. Regarding the throttle body removal; Do I need to worry about coolant pouring out when I remove the coolant carrying hose from the throttle body?

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Saturday, October 31st, 2020 AT 9:11 PM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

I don't believe there are any hoses that need to be removed. It does indicate disconnecting the coolant temp sensor, but that is an electrical connection.

Let me know.

Joe

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Saturday, October 31st, 2020 AT 9:33 PM

JORDANNGIAU

MEMBER
34 POSTS

Turns out it does require removal of a pair of coolant hose from the throttle body and lost about an inch off the full line on the coolant reservoir. Took me about 4 hours to finish everything. First, I removed both of the hoses which one of them has rust underneath it, then took out the 3 screws which was also stuck hard, did some hammering and WD40-ing. As inspected, the valve did not rotate freely so I gave it a good clean with some throttle body cleaner and the valve was rotating a lot smoother. Will give it some time to see if the hesitating persists but so far after test driving, it was all fine.

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Sunday, November 1st, 2020 AT 3:21 AM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

Glad to hear you got it taken care of. I looked through the directions again and there is nothing about coolant hoses. Maybe it is of a different design.

Regardless, let me know if things change or if you have other questions. Also, please feel free to come back anytime in the future.

Take care,
Joe