Engine Shudder
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Engine Shudder
1998 Ford F150 4.2L V6 6,000 on remanufactured engine.
Three months ago, received engine code P0340 - camshaft position sensor. Removed the sensor and noticed the metal post in the sensor had become dislodged. Purchased a new sensor, and noticed this metal post appears to be held in place magnetically. Installed the new sensor, engine performance increased dramatically. After a few starts, the check engine light went out.
About two weeks ago, the check engine light started coming on intermittently. Noticed that the light comes on after the engine has a miss or shudder while idling. This shudder last less than a second. The sequence goes like this - Engine shudders, and then amazingly heals itself. A few seconds later, the check engine light comes on, but the engine still runs good. After a few starts, the engine light goes out. This sequence happens about once every three or four days. Any ideas!
Three months ago, received engine code P0340 - camshaft position sensor. Removed the sensor and noticed the metal post in the sensor had become dislodged. Purchased a new sensor, and noticed this metal post appears to be held in place magnetically. Installed the new sensor, engine performance increased dramatically. After a few starts, the check engine light went out.
About two weeks ago, the check engine light started coming on intermittently. Noticed that the light comes on after the engine has a miss or shudder while idling. This shudder last less than a second. The sequence goes like this - Engine shudders, and then amazingly heals itself. A few seconds later, the check engine light comes on, but the engine still runs good. After a few starts, the engine light goes out. This sequence happens about once every three or four days. Any ideas!
Hotshot
Joined: Aug 2002
Posts: 12,679
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From: BC, Canada
Hi miltie and welcome to the forum 
I think the first thing you should do is to take the truck and get it scanned to see what code turned on the Check Engine light. Even if the light is off now there should still be a code stored in memory. Make sure you get the code number and not just a description of it and someone here will be able to help.
I think the first thing you should do is to take the truck and get it scanned to see what code turned on the Check Engine light. Even if the light is off now there should still be a code stored in memory. Make sure you get the code number and not just a description of it and someone here will be able to help.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Did you install the engine or have a shop do it for you?
I'm not positive, but a P0340 can maybe be caused by the Camshaft Position Sensor not being lined up right. There is a special tool that needs to be used to get it all lined up when the CMP and synchro assembly (the part that looks like the distributor) are installed.
I'm not positive, but a P0340 can maybe be caused by the Camshaft Position Sensor not being lined up right. There is a special tool that needs to be used to get it all lined up when the CMP and synchro assembly (the part that looks like the distributor) are installed.
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I had a shop install the rebuilt engine for me. When I replaced the CP sensor, I only replaced the sensor. I did not remove or mess with the drive assembly (the part that looks like a distributor). From what I could see, the sensor could only go on one way.
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I guess it's possible the shop initially set the synchro correctly, but didn't get it secured properly, and possibly it has moved out of its proper adjustment. It ran fine without the check engine light coming on for about five or six months, but since then the light has come on and then back off several times.
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Hotshot
Joined: Aug 2002
Posts: 12,679
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From: BC, Canada
I found a Special Service Message today about the P0340.
Basically it says that if you follow the pinpoint tests in the manual and dont get anywhere that you may have "interference in the cam sensor circuit to the PCM".
It says this could be caused by aftermarket or open spark plug wires, alternators that exhibit excessive RFI,and the ground path on aluminum bodied DPFE sensors. The replacement DPFE is plastic to eliminate that problem.
To me this sounds like they are grasping at straws but they've obviously seem this problem enough to qrite the SSM on it.
Basically it says that if you follow the pinpoint tests in the manual and dont get anywhere that you may have "interference in the cam sensor circuit to the PCM".
It says this could be caused by aftermarket or open spark plug wires, alternators that exhibit excessive RFI,and the ground path on aluminum bodied DPFE sensors. The replacement DPFE is plastic to eliminate that problem.
To me this sounds like they are grasping at straws but they've obviously seem this problem enough to qrite the SSM on it.
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