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knock analyzers on stock ECU

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Link have a product called the Knock Link, which is a warning system. Here's a link to their product description.

I've used this along side an audio knock detection and is pretty accurate, a couple false alarms during gear changes but that's not really a problem area

Why would you attach the knock sensor to the inlet manifold??.... its cushioned by a soft gasket.

It's more a case of necessity Marek, or when there are simply no other options - You'll note I listed that as my least desirable location. That being said, with the inlet manifold bolted up tight to the cylinder head, the vibration of detonation will still transfer into it. If you are using a thick phenolic spacer to cut down heat transfer then this might be less desirable or effective.

I just bought a PLEX and plan to use it on my Bug Eye GDA 2001 WRX with EJ20.

Not expecting anybody to know this but......

The ECU outputs a signal to the Tach via C9

Can I tap that directly from the ECU to run my PLEX?

Would there be a smarter way to run it?

I am open to perma install as its going to be my learning tuning test bed.

Plex wiring info here.

I would run a new knock sensor rather than tapping into the ECU signal. Knock sensor wiring is always shielded and tapping in can cause interference which will screw up the ECU trying to recognise knock and also the plex

The tacho signal will give the Plex unit rpm, but to provide individual cylinder knock detection you really want the Plex unit to know which cylinder is firing at any time. I'd recommend using the trigger signal for the #1 coil instead of the tacho signal.

Okay thank you Andre.

I've noted the only factory knock sensors I've seen have had a raised area they bolted to.

Will a flat surface with a bolt hole do the same job and is the torque specs on the bolt critical to how the knock sensor reads?

My cars EJ20 and I have not looked for mounting locations as of yet.

You don't need a raised boss to bolt the sensor to, just a flat mounting surface. The only thing to watch out for is if the surface is recessed slightly and the outside edge of the knock sensor ends up fouling on this before the knock sensor pulls down properly.

Has anyone used the new LinkG4+ knock block?

I'm still deciding on which one gives best bang for buck.

We just got hold of the new Link G4+ Knock Block and I've done some testing so far on the Porsche 996 TT that we have in the shop at the moment and I'm really impressed with it. It's nice and clear and the onboard battery with USB charging is a great addition - No need to connect to battery power on the car or constantly replace batteries.

Hi Andre

I am now looking at buying a knock monitor or knock audio device. I look at both the Plex unit and the Link G4+ knock block. I have run through the forum and found that both units have good performance.

For Plex it will give you the option to have a single or dual sensor option and also an additional CAN Bus connection function which I am not sure what is it for. As the more you choose it will be more expensive.

On the other hand the Link G4+ knock block does not have so much of an option if compare to the Plex. But price will be way approachable.

The question is I am just starting to jump into this industry, do i need such an advance unit like the Plex or actually I can make do with the Link G4+ knock block?

I do foresee I will need to tune V Engines can i make do with only one knock sensor ?