Question about 1994 Ford F150 Styleside Supercab
The trucks engine rpm increases and decreases at idle. runs fine on the highway. sometimes at lower speeds i press the throttle and get no response then the problem goes away and all is normal. also the engine light comes on intermittantly.
I know this sounds stupid, but I replaced my pcv valve recently and shortly after I began having the check engine light and some sputtering at starts. I replaced the grommet and it went away. I think the replacement pcv was a touch smaller and there may have been a vacuum issue. I had it hooked up to a computer and showed no issues. Cheap and easy maybe fix???? Hope this helps.
Posted on Aug 31, 2008
Throttle position sensor or idel speed sensor may be the problem
Posted on Aug 27, 2008
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The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.
Conditions for Running the Throttle Learn Procedure
• DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.
• The engine speed is between 450-4,000 RPM.
• The manifold absolute pressure (MAP) is greater than 5 kPa.
• The mass air flow (MAF) is greater than 2 g/s.
• The ignition 1 voltage is greater than 10 volts.
Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code
(DTC) List - Vehicle.
1. Start and idle the engine in PARK for 3 minutes.
2. With a scan tool, monitor desired and actual RPM.
3. The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
4. Ignition OFF for 60 seconds.
5. Start and idle the engine in PARK for 3 minutes.
6. After the 3 minute run time the engine should be idling normal.
Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.
* If the engine idle speed has not been learned the vehicle will need to be driven at
speeds above 70 km/h (44 mph) with several decelerations and extended idles.
7. After the drive cycle, the engine should be idling normally.
* If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds
and repeat step 6.
8. Once the engine speed has returned to normal, clear DTCs.
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