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VX 5.7L P0327 knock sensor - Help :(

Heffer_Slayer

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Hey all,

Since washing my engine I keep getting P0327 knock sensor code, which I believe retards the timing of the car and it runs sluggish, and chews fuel!

I have now reset the code approx 3 times, and it comes up randomly.

Notable points when it has come up;
In traffic at 40km/h
Driving on the highway at approx 100km/h

Both times, no load was on the car. So I believe the car is not actually knocking, as if it were. I feel it would come on ALL the time, not just when ever it feels like it, (ie within 1 or 2 minutes of driving).

Other times i won't even come on at all...Could be driving all day, then bam at the end the dreaded light comes on.

Where do i go from here in terms of troubleshooting this code?

I have heard wiring can be damaged or a PCM may be faulty. What is a PCM? Is ir repairable? And where is the wiring so I can inspect it?

The car has the following mods from the prev owner;
Tune
Wade Cam, double valve springs, new pistons, conrods, valves (reconditioned motor)
Pacemaker extractors
Automatic transmission - apparently also modified to suit the built, but unsure of specifics.

Help! :supersad:
 
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DrZ

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Hey mate,
I had the same issue, well relitively, as I am not 100% which knowck sensor that one is, but I had issues with my knock sensor in bank 2, which means the one closest to the firewall, also happened after i degreased the *insert expleative* out of it..

You got it right, it changes your timing by 3 degrees to make it safer, and boy do you chew some extra fuel (and will be pumping out black soot every time you tramp it).

I currently still have the same knock sensor in my car, there is a lot of how to's on how to change it, but they go for 130-170$ and usually need to replace the loom as its plastic and tends to break when you remove it (add another $100 there). All that scared the crap outta me as I didn't have (still dont) have the spare cash around. I did alot of hwy driving and it always used to do it to me when i go above 100kmph an take foot completely off the pedal.

So my solution, I took it to a tuner, he plugged in his awesome computer and watch me replacte it over and over, they can see if your car is knocking or not with all the AFR readings etc and said it was safe to just desensitize it. So thats what he did, desensitized it, i tried to get it to happen a couple more times, wouldnt do it, so.. I class that as temp fixed till I have the cash to replace it properly.

The tuner said he often does this on solid roller cams, large cammed cars, and to cars with alot of heavy duty valve train as they chatter sometimes and cause it to go.

Don't know how much it would cost as the guy did it out of his kind heart. But if someone had to charge you i would assume itd only be for a touch up tune at worst.. so hopefully not much..

Hopefully this helps at all man.
 

Brett_jjj

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Carefully check the knock sensor wiring and any connections from knock sensor(s) through to the PCM. Unplug any wiring connectors and plug them back in again, even if they look fine, do this just to make sure 100% that they have a good clean tight connection, check for any corroded, bent or backed out pins in the connectors.
If the wiring and connectors are all ok, you may have to try new knock sensors. If the problem is still occuring after fitting new knock sensors, then the only thing left really is to try another PCM (Powertrain Control Module), also called an ECU. This is the computer that controls the engine and transmission if auto. If another PCM is fitted, the body computer or BCM (Body control Module) will need relinking to the PCM before the vehicle will start. This is a feature of the vehicles security system and the BCM/PCM relinking is done with a suitable scantool.
 

Heffer_Slayer

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May sound silly, but where is the PCM? As you said you are referring to the ECU, wouldn't that mean I loose my tune? The car is a auto.

Thanks very much DrZ...that might be my end solution if i can't fix the bugger, so i take it he just deactivated it?


Also. without causing too much confusion, another thing i have noticed is when pulling up to a set of lights, my instant fuel economy goes absolutely haywire, spitting out figures of 30 or even 40L per 100. Is this normal? Feels like the transmission is down shifting as i pull up, but could be just the cam interfering with what i believe is the stock stall converter...though i might post another thread about that issue, as the knock sensor/engine light is driving me nuts!
 

DrZ

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May sound silly, but where is the PCM?

Thanks very much DrZ...that might be my end solution if i can't fix the bugger, so i take it he just deactivated it?
Nah just desenitized it, because you don't want it to not be able to hear the knock, just send lower voltages when it thinks there is a slight knock (false knock) but when it gets worse (real knock) it will send enough voltage through for it to then engage that 3 degrees of timing so you save ur engine.

If you really want the tuner can even play with how many degrees it will be affected by if it does come on.

- Drz
 

Heffer_Slayer

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thanks for clearing that up mate :)

Do you need to replace any gaskets when you take the intake/plenum off?
 

Heffer_Slayer

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Was just looking at both those threads :)
Much appreciated
 

lout

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it may be a lean knock at cruise timing
check you didn't knock any vacuum hoses loose when you washed the engine
get a decent mechanic to plug a scan tool in and check what's wrong don't just dodgey it up
check if it is going into closed loop
 
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