Changing the I6 Knock Sensor?

[sly]

Has anyone done this & written a how-to that's escaped the search function?

I have a P0325 DTC up, knock sensor circuit. Symptoms are exactly the same as the time I had a knock sensor replaced under warranty. 3 manuals, no pictures, only the advice that it's bolted to the block near #5 cylinder on the intake side.

Any pics most appreciated.

[5.0 ED]

Yeah its under intake but above the starter motor hidden away there, it just unscrews and you screw the new one in and plug it in, but being that it is the 2nd time you've had the fault, i'd be checking the wiring to it, and giving the plug a clean while your at it.

You can check the knock sensor with a multimeter it should be under 10k, its basically a microphone in a resonance chamber designed to sound an audio style output when knock is heard, and your fault saying high means that its open circuit i would assume, so you should be able to tell that fairly easy.

I'll just add that on earlier models, not sure about AU, but inside the ecu is a little bored that soldered off on an angle, it is the knock sensor board, and to me they do look like they could get damaged due to normal driving conditions, it just hangs off to the side on a right angle with soldered pin's holding it in.

[sly]

Originally Posted by 5.0whiteaughia

You can check the knock sensor with a multimeter it should be under 10k

That's 10k Ohms? How do you test it, across the 2 wires or from 1 of the wires to the body? Do you test it in place or loose? If in place, with ignition on or off?

I tested both the old and new ones loose on the bench, across the wires, then red wire to body (earth) then white wire to earth. Both showed open circuits in each case.

Ran OK for about 20 minutes then started pinking again. : I have the knock sensor DTC up again. Manual says if it's not the knock sensor it could be wiring or the ECU itself.

I have an intermittent flat spot from about 1800rpm to 2500 or so. Sometimes it's mild, sometimes it's hugely flat and the engine almost chokes to a standstill. Sometimes it's not flat at all. The only DTC showing is the knock sensor one.

I'm doing some basics tonight/tomorrow. New spark plugs in, new coilpack going in along with fuel filter. If no difference after that lot, where to next?

The old plugs have maybe 20,000km up but have been there through a patch of running really rich (like low 10's or less under load). They don't seem fouled, a bit sooty in the middle, light brown/grey on the outer electrode. But #4 stands out, the centre insulator is orange where the other plugs' insulators are still white.

Oh and now one of the HLA's is getting noisy. Starting to tap-tap-tap at idle. Oil is new, changed 3 days ago & still on the "full"mark. Every oil change in the last 5 years has had a flush put through before draining.

I'm starting to think a BF wagon from the auctions is looking a good prospect. 2 year old, 30,000km cars are going for $13,000 ATM.

$13,000... <insert word here> me!

[sly]

I had my suspicions that it might be somewhere near the starter motor. So I'll have to do the job by feel?

I'll see what I can do with the wiring. Yes it is a repeat, but the last failure was 7 years and 250,000km ago.

[autickfordfairmont]

How much roughly for a new knock sensor???

[5.0 ED]

well probably best done on a hoist from underneath the car, if a hoist is not available, then i hope you have a long arm that you can fit down there after removing airbox etc to make room, either that or you'll need to take the intake manifold off.

[sly]

No airbox... supercharger and pod. Much harder to remove.

A new unit from Ford is $140. Didn't have time to shop around, you may do better at the usual suspects: Supercheap, Repco, Autobarn etc.

[james22]

$35 from FTG. I asked them this morning cause my knock sensor is buggered too.

[5.0 ED]

you could always get rid of it, and put a 8k resistor in its place. ;)

[InfernoSR]

Might sound stupid... but anyone got a pic of the knock sensor in the AU I6?

[sly]

Originally Posted by BLUEPRINT

Might sound stupid... but anyone got a pic of the knock sensor in the AU I6?

I have a pic on the camera, but the batteries are flat & there are none in the charger ATM. I'll put the pic up as soon as I can.

[5.0 ED]

The pin's should read 10k or below between them according to the ford thing on it i read.

What i'd do if i was you sly is get the plug off, disconnect the ecu completely, and then measure between the wires for the knock sensor, and it should read open, and then put a pin between both to short it and it should read below 1ohm i'd assume.

If that tests ok, then open up the ecu and visually check around the little board that is on the pcm at a 90 degree angle, i expect that sometimes they could crack the solder due to the way its mounted and therefore would need a touch up with the soldering iron.

[sly]

Originally Posted by 5.0whiteaughia

The pin's should read 10k or below between them according to the ford thing on it i read. .

Found some info in the Haynes manual. It says there should be at least 10k across the sensor?

It also says the + wire in the harness to the sensor should get approx 3 volts from the PCM. I'll try their tests and yours as well, & see what happens.

[sly]

OK, neither wire to the knock sensor gets 3V from the PCM. But then the pins on the PCM are labelled as inputs on the wiring diagram. And would a piezoelectronic crystal need a 3V source?

The wires between the PCM and sensor plug do as they should according to the multimeter, they read open when open and SFA when shorted at the plug.

So if the manual is right about the PCM supplying 3V, then my next logical step is to replace the PCM. I've got a sparky lined up to code a PCM to my BEM on Monday, and the local wrecker has a couple with the right code for $125 each. I know they're cheaper elsewhere, but time is a bit of an issue ATM.

Had a look inside the PCM Matt, there's no little board at 90 deg that I can see, everything seems to be surface mounted and covered in clear lacquer. You were looking in your EF ECU? Maybe it's a bit better integrated in the AU?

Anyway must go now, dogwatch from tonight to Monday morning. Most likely offline until after I've been to the sparky.

[bondy99]

Any follow up to this? Thanks