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98 escort engine idle issue

3K views 9 replies 4 participants last post by  Bert 
#1 ·
I have a 98 escort that 90% of the time runs just fine but every now and then will high idle. It wont stop or change until I shut the car off, once the cars off and I restart it, it runs fine immediately. I had first suspected rust in some part of the throttle mechanisms (being as the car is from the midwest) but since it goes away as soon as I shut down then restart the car I'm beginning to lean toward a sensor or something going tits up. Anyone have any ideas ?
 
#2 ·
I have a 98 escort that 90% of the time runs just fine but every now and then will high idle. It wont stop or change until I shut the car off, once the cars off and I restart it, it runs fine immediately. I had first suspected rust in some part of the throttle mechanisms (being as the car is from the midwest) but since it goes away as soon as I shut down then restart the car I'm beginning to lean toward a sensor or something going tits up. Anyone have any ideas ?

:hit::hit:

Hello and good day:

I would look to two items that is a well know factor with Ford's, and their Idling Problems...

1. On the Throttle Body there will be something called a TPS (Throttle Positioning Sensor).

The function of the throttle position sensor, aka TPS, is to supply information to the car's computer about the position of the car's throttle. The throttle position sensors contain electro-mechanical moving parts which are prone to wear and tear, which eventually add to the cost of car repairs. Malfunctioning of a TPS can result in improper data being fed to the car's computer, which monitors engine performance, in respect to the fuel efficiency of the car. A damaged, malfunctioning TPS can cause variety of symptoms which are also known as symptoms of a bad throttle position sensor.

Symptoms of a Defective Throttle Position Sensor
Following is a list of symptoms, either of or a combination of which, a car driver may experience because of a defective throttle position sensor:
  • Bucking and jerking of the car
  • Idle surging
  • Sudden stalling of the car engine
  • Hesitation while the driver of the car is trying to accelerate
  • Sudden surge in car's speed while driving on the highway
2. On the top of the Upper Intake Manifold there will be a IAC (Idle Air Control Valve)

An IAC (idle air control) motor is designed to adjust the [COLOR=green !important][COLOR=green !important]engine[/COLOR][/COLOR] idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or ECM (electronic [COLOR=green !important][COLOR=green !important]control module[/COLOR][/COLOR]) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. An IAC motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the IAC control motor to react slowly, either failure can cause the engine to stall at idle. When a [COLOR=green !important][COLOR=green !important]trouble code[/COLOR][/COLOR] scan is performed it sometimes won't always detect a failed or weak IAC motor. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed, also inspect the IAC for a build-up on the seating (pointed) end and clean as necessary


I hope this Info will help...any further help please feel free to come again.
 
#5 ·
I've got no check engine lights will there still be codes if there's an issue?

I had a problem with the TPS in my taurus a while back that threw a code.....If the TPS is my problem does anyone know if this sensor is like the one in my taurus that has to be adjusted after installation in order for it to work properly or is this something I can just change?

If it does have to be adjusted, does anyone know how to do it? Or possibly know a website or book that I could find out how to do this myself?
 
#9 ·
TPS sensor it is! Has anyone had to pull one on this model before? Any tricks that would make it easier would be much appreciated. The screws to remove it are about 2 inches from the master cylinder and some brake lines and I cant quite get enough pressure to break that screw loose with a phillips bit and a 1/4 inch open end wrench without stripping the screw....... I'd rather not take apart the intake and such
 
#10 ·
It should be able to be removed with just taking the air filter tube off. Be aware of this caution.
CAUTION: Slide the rotary tangs of the TP sensor, rotated one-quarter turn clockwise away from their final installed position, into place over the throttle shaft blade, and then rotate the TP sensor counterclockwise only to the installed position. Failure to install the TP sensor in this manner may result in excessive idle speeds.

Note: The TP sensor is not adjustable.
 
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