So i have a diagnostic code of P0325 with NO check engine light on, but have a rough idle/hesitation and decreasing gas mileage. I replaced all plugs with motorcraft plugs a while ago before the rough idle (dry torque to 30ft-lbs) started. I cleaned mass air flow filter (K&N oil based) and cleaned mass air flow sensor. And i just replaced coil pack with MSD Blaster i think there called (red ones). As it runs and idles much better still have the code P0325, Could it be that its just the sensor that needs to be replaced? Any help would be awesome.

I forgot to say when i check obd2 misfire monitor $53. i get a value of 51. what ever that means. Ill pull the coil out switch it to see if its coil (I just bought new ones still happening) and disconnect battery and the misfire value does to a different cylinder and each time the cylinder keeps passing

Thansk kc

 

Want to tell us what type of truck and engine and year?

Before you change the knock sensor make sure you check your coils and sparkplugs for a misfire (bad boot on the coil on the coil on plug), or if you have the 2 coils boxes them breaking down plus the wiring to the plugs.
You said in your post, you changed the plugs a while back on changing the plugs, how long back?
I have seen plugs right out of the box not work, some work a day, some work a month and some be still working after 150,000 miles on them. (Which affects your truck running and milage.

Now the check the wiring harness to the plugin on the knock sensor as well as making sure it is plugged in all the way.
(1997- early 2004 f150 4.6 has two sensors mounts on some mounted to the block under the intake and 5.4 has one on the block under the intake. 1997-1998 are interchangeable with each other, but the 1999-early 2004 only can be changed with each other as the plugin is different from the harness. Now facing the engine left-hand side at the rear of the engine around the intake mounts to head to the back of the head area sets the plugin to harness.)

Think of the knock sensor as a microphone listing to your engine as a doctor does to your chest when you go see him or her. If the knock sensor hears something like a plug or a coil ark, not go boom in the hole it chirps up.

P0325 stands for knock sensor circuit malfunction. This means the PCM has detected a problem with the knock sensor or its circuit. Some vehicles may be equipped with two knock sensors.

Very rarely have I seen one of these go bad as it is usually a plugin not plugged in all the way or a damaged wire in the harness.

 

oh yea its a 2001 ford f150 xlt 5.4L 2 valve

I have a Launch crp129e obd2 scanner. And when i check the obd2 mode $06 misfire $53 all cylinders will pass, but one cylinder will have a test value of $0051 but still passes. ill pull the COP and swap it to another cylinder, disconnect the battery and prolly after 5mins of driving ill get the same code P0325 and the test value of 51 in random cylinders (1,2,4,6,6) those are the cylinders that get the misfire 6 got it twice now i think.

The spark plugs were done prolly 2-3 weeks ago
I havent checked the knock sensor wiring harness yet, im gonna take my alternator off to see if i can reach it in the back, if that fails im just gonna pull the intake off to make it easy.

 

Reach over the left hand inside, side of the passenger head, and you will find the connector for the knock sensor on the back side of the engine.
Never seen anyone with that long of arms or that small of hands/arms reach under the intake to reach that plugin.

The bolt that holds the knock sensor in sets just to the left side under the lower intake. The wire runs out the backside of the intake on the left-hand side facing the engine.
Can't remember the size of the bolt. It is not that big and looking at one you would expect more than what you get. It is like a connector to a wire that the bolt runs through and bolted to the block with a wire and plugin attached I want to say two wires are in them.

If it was me, I would pull the plugs out and look them over well and check the gap to make sure those are correct and clean. If you are having a miss fire test value of 51 in random cylinders.
How long have the coils been on your truck?
Ford says to change them and plugs at 100,000 miles tops as they will break down and not throw the correct spark.
They also say it is recommended to change both at 50,000 miles.

 

I just put the new MSD coils in last night. i cleared the code twice and comes back with in 5 mins. I cant remember if i said i dont have a check engine light on.. There a mis/hesitation when i hit the gas peal.Yea ill pull the spark plugs to and check them out. I also had this problem before i changed motorcraft spark plugs.If i had a bad spark plug wouldnt that cause a cylinder to fail? They always pass on the scanner.

I just cleared the codes on truck went for a drive and got the code P0325 and i checked test $53 and all cylinders.pass and there no test value on any cylinder. and this has happened before.I im starting to think that the knock sensor wire is shorting out

 

Well I think I might have found my problem here. I hope this fixes it

 

Hum, could be.

 

What was the problem? I can’t tell by the picture. I have a similar issue.

 

Good job
Got a kick out of this thread
Replace a knock sensor on a supercharged Nissan Frontier and you will have lived
These Fords and the 5.3 GM are a cake walk