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Dieseljunky2
Dieseljunky2, Ford Mechanic
Category: Ford
Satisfied Customers: 3946
Experience:  ASE Certified, Ford Certified, Cummins Certified, & 20+ years in field experience
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1994 Ford F150: /302 has check engine light..intermitently..cap..rotor

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My 1994 Ford F150 w/302 has check engine light on intermitently does not have much power. I have changed oxy sensor ,plugs , cap and rotor. seemed to run better for a while now check engine light but now its backon intermitently. ???

Dieseljunky2 :

Hello, do you know what the code is for the check engine light?

Customer:

No I don't have code reader and took it to Ammco and the light was off at the time. It only comes on at highway speed.

Dieseljunky2 :

Has the fuel pressure been checked while driving at highway speeds?

Customer:

No it hasn't

Customer:

I purchased a new fuel filter but haven't put it on yet

Dieseljunky2 :

Here is a picture of the test connecor located near the driver side hood hinge. Locate it and install a jumper wire as shown. Then get in the truck and make sure everything is off, then turn on the key, but do not start the engine. Now watch the engine light. It should start to flash. It will flash a number (count the flashes), pause then flash another number and pause, then flash a third number. Write down how many flashes each time, the code numbers are 3 digits. Now watch closely as if there are more than one code, the flashes will continue untill all codes are flashed. Turn the key off after the flashes are fininshed. Let me know what the codes are. Thanks

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Customer:

Does 121 mean anything?

Dieseljunky2 :

121 is for a faulty throttle position sensor. That would cause the problems you are having. Has the throttle position sensor been replaced?

Customer:

Not seince i have owned the truck

Customer:

Is that something I can replace myself?

Dieseljunky2 :

Yes, it is near where the tubes from the air filter hook to the engine.

Dieseljunky2 :

here are the directions from the manual.

Dieseljunky2 :

REMOVAL

1. Disconnect negative battery cable.

2. Disconnect Throttle Position (TP) sensor from wiring harness.

3. If reusing TP sensor scribe alignment marks to position when reinstalling.

4. Remove two retaining screws.

5. Remove throttle position sensor.

INSTALLATION

CAUTION: Slide rotary tangs into position over throttle shaft blade, then rotate throttle position sensor CLOCKWISE ONLY to installed position. Failure to install the throttle position sensor in this manner may result in excessive idle speeds.

1. Position the throttle position sensor so that the connector points opposite the Idle Air Control (IAC) solenoid. Then rotate throttle position sensor clockwise to align scribe marks.

2. Secure throttle position sensor to throttle body with two retaining screws. Tighten to tighten to 1.2-1.8 Nm (10.6-16 in lb).


3. Connect electrical connector to harness.

4. Reconnect negative battery cable.

NOTE: When the battery has been disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module relearns its adaptive strategy. The vehicle may need to be driven 10 miles or more to relearn the adaptive strategy.

Dieseljunky2 :

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Customer:

are they expensive?

Dieseljunky2 :

I will check, back in a few. Thanks

Dieseljunky2 :

$35-50 dollars at most autoparts.

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