diver64

2004 F150 XLT with the 5.4 Triton. I got a check engine and stopped to check it out. Code came up PO325, Knock Sensor. I'm having a hard time finding out where they are and if I can do them myself.

Is is necessary to take off the manifolds as the Chiltons seems to say? Doesn't make sense that they are under the manifolds on the bottom of the engine. Just where exactly are they located and can I do them? Looks like one bolt to the engine and a connector.

redfishtd

I believe sensors are under intake manifold on top of engine . You must be very careful with routing of wires thru intake runner linkage it is not how you would think it would go . Knock sensors are micro phones . In fact they test them by using a tapping hammer . Also be very gentle when placing intake back as its easy to damage cly head temp wires .
Yes you can do it if you are careful worker .Take pic's as you go and drawings . Drawings sometimes are better to re read . You will have a lot of cleaning to do on intake and TB . Oil orings on injectors on re install .Inspect plastic linkage on IRMC linkage for wear . Blow all dirt off before opening up .
Problem is maybe some engine noise is causing this knock noise .We often blame the sensor --shoot the messenger . Bad fuel ????? Worn engine part?? Listen to that engine .

F150Torqued

@redfishtd is spot on. I had to replace my IM for crack in plastic molding weld underneath. If I can do it (at the young age of 72 like redfishtd) - you can do it too.

Picture is worth a thousand words, so here's ya' one.



Couple of EXTRA words of 'advice/encouragement/caution. Remove HOOD LATCH before you start to avoid poking holes in your stomach. Have a piece of 1/2 board about 18" long to prop under passenger passenger side of IM while 'jostling it aroung' --- to avoid damage to CHT sensor wiring plug like redfishtd mentioned.

While IM is off, tie the factory wiring harness _UP_ along and against the firewall with something. It gets 'tired' and sags - binding on the CMCV linkage. (I only recently figured this out). As redfishtd said, it doesn't look like it - but the KS1 and CMCV connector harness goes BETWEEN the CMCV linkage and the back of the manifold. NOT against the firewall (it will rub & hinder CMCV operation). CMCV operation is important for developing full power.

You can (but you'll come to doubt it) reconnect the Brake Booster vacuum line by sitting the IM roughly in place, laying on your side - across that hood latch - and reach UNDERNEATH the IM and 'feel for it'.

Good Luck.

diver64

Bad gas can cause it? I did just fill up. I'll run the gas out and fill up elsewhere first. I hear no noise from the engine at all

redfishtd

Bad gas can cause a knock as well as other engine problems . I;m not saying you have a knock ,I really don't know how it determines a faulty knock sensor . If its not making engine noises maybe it is bad .His hammer test didn't work like he said the knock sensor is dialed in to a certain frequency that can damage engine . I never fought this battle myself .
Like f150t said get you some foam so you can lay up there and don't put pressure on vcts they can break .He told you about the vacuum lines on the rear of the intake .The 04 has 2 vacuum outlets .A small one and a large one that goes to the brake booster side . The newer ones 05 and up has the small fitting but it is not drilled out . They combined the two with a metal wye near the brake booster .The little fitting gives you 04 guys fits trying to get it back on with out pulling intake .The big line didn't have clamps on it originally either and was a recall .I think you will do fine just be gentle and get the right torque values .




I know this video is for a 2v intake but it may help anyway

redfishtd

https://www.obd-codes.com/p0325

diver64

Thanks for the link.
"A knock sensor tells the engine computer when one or more of your engine's cylinders are "knocking", that is, exploding the air/fuel mixture in a way that delivers less power and can be damaging to the engine if prolonged."

Could a bad coil pack on one of the cylinders do this? I replaced them when I had one of the rods replaced last year or year before when it jumped time and I'm pretty sure that the engine shop didn't use OEM. If that was the case, though, I'd think that I'd have another code or two.
What's leading me to believe it's not something more dire is that there is no noise and the p0325 is the only code coming up. I'd like to explore every option before pulling that intake manifold off.

F150Torqued

I don't believe there is any way a bad coil could be the cause. Failure of proper ignition is detected by PCM detecting absence of slight boost in crankshaft rotational speed corresponding to ignition command. "Knock" would have to occur at preciously the right instant of spark command, or it would be detected as a misfire, producing a 030x code. I guess that would NOT be called 'pre-ignition' - another term used for Knock.

Considering the reported prior work (by others), I might be suspicious of wiring or connection problem in the KS1 sensor (either plug connection or abrasion by rubbing CMCV linkage). You might disconnect battery, 'unplug the Engine Control plug (Center one) from PCM, and ring out KS1 wiring (Pins 48 & 49) for open - shorts to ground etc. IDK what series ohm reading 'should be' of the knock sensor - but you could compare it to KS2. Attached is engine wiring diagram.

If you have or use or have access to Torque Pro app scan tool, the OBDII PIDs for knock sensors are: KS1 = 16E6. KS2 = 16E7. Equation is (A*256+B)/13107 for a reading of zero to 5 volts. P0325 says the reading is out of normal range HIGH. That will limit timing advance dampening performance. They are pretty sensitive. I can tell you - I had a noisy A/C compressor and It caused my KS1 reading to be elevated - but did not produce P0325. After replacing A/C Compressor - they both run very balanced between Bank1 & 2.

dukedkt442

I can't offer specific advice on the knock sensors, but will recommend that if you pull the intake to replace them, you replace the cylinder head temperature sensor while you're in there. It can be done with the intake on, but it isn't fun. The part is $16 and definitely falls into the "might as well" category.

diver64

Considering the reported prior work (by others), I might be suspicious of wiring or connection problem in the KS1 sensor (either plug connection or abrasion by rubbing CMCV linkage). You might disconnect battery, 'unplug the Engine Control plug (Center one) from PCM, and ring out KS1 wiring (Pins 48 & 49) for open - shorts to ground etc. IDK what series ohm reading 'should be' of the knock sensor - but you could compare it to KS2. Attached is engine wiring diagram.

I'll do that before taking off the manifold but first I have to change the ignition module on my 97 CRV. Seems every vehicle has had something go wrong at the same time.