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I am trying to locate the knock sensor on a 2000 F-150 4.2 V-6.
2000 F-150 4.2 L V-6 117K Miles
This engine has severe spark knock / detonation when cold. The knock occurs when the engine is under any load such as gradual acceleration. The knock does not occur when revving the engine while in park or neutral. Once the engine reaches normal operating temperature the knock is gone. Also, once the torque converter locks up during cruise, even with a cold engine, the knock disappears. Upon unlocking the torque converter the knock returns. This problem does not generate any fault codes.
Does this engine have a knock sensor? I have looked everywhere and can not locate it.
Does the PCM adjust ignition timing to coincide with torque converter lockup?
Does anybody have any suggestions? I appreciate any and all input.
the knock sensor is located on the passenger side of the engine block just in front of the starter. you could have a mass air flow meter that is giving a bad barometric pressure signal to the pcm that would cause it to run lean causing a lean spark knock or a restricted egr system that is dumping to much egr gases to only a few cylinders.
My Chilton manual also states that the knock sensor is located on the right side of the block, but it is not there. Any chance it is under the intake like on the V-8. I will have the engine scanned in the morning and will check the baro pressure signal as you suggested. Can the EGR passages be cleaned without removing the intake?
the passenger side of the engine is the only place i know of.i see that you are from texas and the barometric press. should be between 154 to 157 hz if not then the mass air flow meter is either dirty or going bad. i havnt had any luck cleaning the egr ports without taking off the upper intake and egr valve.
I had the engine scanned. The mechanic who performed the scan could not find anything abnormal. He scanned it twice. The first morning while idling in Park (noise not evident). The second morning he drove the truck duplicating the problem with the scanner attached. He suggested that it was a lifter that is slow to pump up. I have a very difficult time with his theory since the noise is only obvious during vehicle acceleration when the engine is cold. Once the torque converter locks up or the engine reaches normal operating temperature the problem goes away. This is very repeatable and very predictable. The problem is the most obvious after the truck sits overnight. The colder the night, the more pronounced the noise. In my opinion, valve train noise (i.e. lifter slow to pump up) is not sensitive to changes in engine load but instead will vary in frequency based on engine RPM. Additionally, valve train noise will be evident any time the engine is running with or without a load. Do you concur?
My local Ford dealer upgraded the PCM software. This had no effect on the problem. The shop Foreman also told me that some of the 4.2 engines do not have a knock sensor installed. Instead, these engines have a plug installed in the threaded hole. My 2000 F-150 has the plug and not the sensor.
I would also check for exhaust manifold and flange leaks. Sometimes these leaks make a 'ticking noise' that wouldn't be very evident at idle but under load could be mistaken for an engine 'knock'. The symptoms also are very same, cold starts, acceleration then goes away as engine warms up.
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