i've got a knock link on my P1 but the previous owner had it installed, so i'm not really sure what it's telling me.

Occasionally when i boot it, it flashed down into the red... should i be worried about this....?

Apart from that, while i'm cruising it rests happily at 'normal' but flashes now and again, is this ok...?

Thks

 

There are various views on the Knocklink, I personally think they are a waste of time as most people just fit them and adjust it until the red light isnt displaying not much good if the engine was knocking in the first place

Just another flashing light to make you paranoid and impress the chavs outside tesco's.

 

Are you another PSLewis clone?

That's very bad advice given the model in question is a P1, and is fairly well known for detonation related engine failures....

P1vic: Ideally it should never flash down to the red LED.

The KnockLink monitors detonation (fuel air mix exploding before the spark is fired). If it is occuring it puts tremendous strain on the engine as the combustion occurs before the piston reaches the top of its stroke, therefore pushing down on a piston that is still moving up. This can cause big end failure. The increased combustion temperatures and pressure caused by det can also melt pistons or blow holes in them.

The P1 was designed to run on super unleaded, which I assume you are using, and also has some octane boosting agent in the fuel tank. It may be that this is not effective anymore and you should add some octane booster to the fuel. The MAF sensor could also be failing (common problem) and this can cause det, new one is £70-£80 from a Subaru dealers. Five minute job to swap.

Best bet is to get it to a local specialist and get them to give it a once over. In the longer term its worth considering investing in having your P1 re-mapped (if it isn't already) for UK fuel.

 

Davey is speaking out of his bottom again

When you fit them, it is recommended that you turn the sensitivity up to max and most people do this.

If you get a red light - This is not noise or anything else it is detonation (or a slight crackle of det).

Detonation can kill your engine in a split second. Dont rag it. find out the cause.

Try running higher octane petrol or a bottle of booster first and see if it goes. Then start down further diagnostic routes.

 

Nice one Graz, you beat me to it!

 

Ok then Einstein, what if the engine is already suffering from slight detonation/pre-ignition, you calibrate your little light to go out and you feel all happy and warm in the "apparent knowing" that your engine is safe and sound. And thus you drive like Colin McCrazy because you think your over-priced little black box makes your engine invincible.

 

Lets get a few things straight then shall we [Davey] as you obviously know **** all

Most people do not fit them then adjust so the red light doesn't show. Any instuctions I've read here clearly state to fit the KnockLink and set the sensitivity to MAXIMUM and is as recommended by many respected tuners who post here (e.g. Bob Rawle, Andy F., Pavlo, to name but a few). After fitting it should also be tested to ensure its functioning by tapping the sensor mounting bolt with a spanner and ensuring all the LEDs light.

If it's going to save me £2k for an engine rebuild then I don't mind a few flashing lights. If anything I'd be less paranoid especially if I had an import, P1, or modified Scooby. If all is well none of the LEDs should flash, just the bottom green faintly lit to indicate it has power, bottom green LEDs will flicker a bit at high revs / boost.

So the original poster and P1 owner should be even more concerned that their KnockLink is showing the occasional red LED in case the previous owner has foolishly turned down the sensitivity. Though I doubt very much that they have! Yes it doesn't make your car invincible but it is certianly a good aid to ensuring everything is running properly with the sensitivity set to the max.

Understand now?

 

You've still not explained what happens in the instance the the engine is already knocking?

So "tapping the engine with a spanner" is the official method used by tuners for testing knock sensors? Please give me a list of their names so I know who to avoid.

You feel you can call me stupid when you clearly havent a clue yourself?

 

No offence here. But if i was the guy that posted the original thread i think its quite obvious who knows what there chattin about! So just follow there advice and they may end up saving you a lot of money. Ignore the other bloke as he seems to be a bit slow on the pick up.
Good to see some advice coming out though!! shame theres always one that tries to **** on the fireworks!

 

My Knocklink enabled me to return to a mapper (when I was tied into using ECUTEK) to get a tweak after it was mapped on the rollers and I then noticed that on the road it was detting (due to RED lights on KL).
This they confirmed upon my return with their detcans.

I have since fitted an Apexi Power FC, and whilst mapping a slight tinkle of detonation could heard with detcans before the Knocklink registered much.

In this instance the KL was only flashing 1 - 2 greens but the PFC was recording a Knock of 24 and a tinkle of det could be heard on the detcans.

KL lighting 'Red' is very audible on the detcans.

The KL in question has always been set to the Maximum from the day it was installed.

P.S Anyone that fits a Knocklink and finds it's hitting the RED on maximum setting should get it checked, before they start messing with it's settings.

 

100% agree if your getting any reds theres a problem.Get it looked at and dont rag it or try to get the red to flash until its had some det cans on it.

 

What are you going on about Davey . tapping the sensor with a spanner is purely a home check thing to check that is actually sensing something. you would be really pissed off if you were hooning along detting your pistons to pieces only to find that a sensor wire had been trapped or cut etc...

could you explain to me how you can tell an engine is detonating without a knocklink/det cans/PFC etc.... It is extremely difficult to tell in the car.

P1vic, ignore all Daveys 'dumb *** statements for effect cos he loves the sound of his own typing' contributions in this thread.

Its purely an early warning system, that may just give you that split second you need to prevent terminal engine failure. exactly like a smoke alarm in your house. It wont stop the fire starting, it wont put it out, but it may wake you up just in time to get the **** out of there.

A bit off activity on the greens is normal and nothing to worry about. if you get the odd amber still dont get unduly worried. you may get transitional readings when you change gear etc. If however you are getting a lot of red you need to back off mate. this is as likely to happen at 4-5000 RPM as it is at high RPM. get someone with a set of cans to confirm if you are worried.

They can be a very good pointer to a number of problems, failing maf-high intake temps-overboosting etc.

They are damn ugly in the standard box, but its just a nice little tool for the conscientious car owner. in a very similiar vein to an oil presure or temp gauge it can save you a lot of expense.

Davey is a **** of the highest order, take anything he says on here (or his alter ego Lewis)with a pinch of salt. I presume he also scoffs at the use of an oil pressure or temp gauge.

Lots of good advice specific to your car at www.p1woc.co.uk and the place is refreshingly free of Daveys and there ilk.

 

Personally I'd use det can's and measure the exhaust gas temperature and oxygen levels.

If your getting detination, the temps are up and its lean as a bitch you'll be in no doubt.. And visa versa, if theres no det, temps are good and so is the air/fuel ratio you can rest assured things are probably ok.

 

Rather than sending my Mrs down to Tescos with the detcans on, watching the wideband and egt gauge, i'd rather she just keep an eye out for the KL Red, lifting out of the throttle as and when required

 

Get it to a specialist to check with an AFR and Det cans mate. Any reds on the KL are not good. No point having a warning device if you ignore it.

Drive it off-boost till then.

Ns04

 

If your getting det won't the egt temps come down(when its detting) as the combustion is incomplete. Also you can get det at any egt value.
It's also not suitible for every one to drive around with a wideband afr meter in the car.

The knocklink is a great, cheap and very a usefull tool, i wouldn't be without mine, its my first sign if somethings wrong.

 

Wearing det cans would make you the real kiddy outside tescos

 

A knocklink is alot cheaper then a rebuild or a new engine

i used to have a MY98 chipped and with induction kit running at 280 bhp ca.

one day i huge plume of white smoke came out the rear end, diagnosed with a burnt hole in piston 3

i had no knocklink or anything else to indicate that my car was detting and i couldnt feel anything with the car until the engine went

now i have a KL in my MY99, and it tells me when my MAF is on its way, twice now ive been saved by this gadget, again i have no way of knowing whats happening in my engine

KL an excellent piece of kit to save the day

 

Your refering to bad timing, detonation is when the fuel air mixture combusts before the spark and before the piston has finished its compression stroke..
And why do you think pistons melt during too much det?

 

Wrong again Davey.

Thats knock you are on about. Detonation is after after the spark.

Detonation occurs when the spark plugs fire and the flame burns too quickly, resulting in the air / fuel mixture detonating, rather than a controlled burn.

Knock occurs when the air / fuel mixture has its temperature and pressure raised to the point where it spontaneously ignites in the combustion chamber without the aid of a spark.

 

We are talking about KNOCK sensors are we not?

 

yes, when i say knock i mean pinking.

There is a small but distinct diffference between combustion before spark and uncontrolled combustion after spark - the latter being what melts pistons.

What you are on about is what you get when you drive your saxo up a hill at 25mph in top gear.

 

Ok, been watching this link, and there's a few opinions on it. Tell me, would I need a knock link on my standard wrx import? Or is it more for the big boys with major mods etc.
Please help as my brain has nearly blown
Thanks, Char

 

No body 'needs' a Knock Link.. They just make some people feel more comfortable.

 

Basically the resonation caused in an engine by detonation is about 6400 Hertz. The knocklink uses a sensor that is designed to operate around these frequencies bolted to the engine block. When these frequencies are detected the knocklink flashes - Simple as that. Its a basic set-up that works well and as people have said can give some early warning to save your engine.

If you want to read some info about det/pinking and pre-ignition (they are all different) have a look at this - http://www.streetrodstuff.com/Articl...tion/index.php

Stu

 

Nope, standard cars can suffer from det too (Faulty MAF, O2 sensor, overboost) If your cars an import then the chances are its designed to run on higher octane fuel (100RON) so if you run it on UK fuel there is more chance of detonation.

each to their own but I personally like to have one fitted!

Stu

 

If the KL showed response to just one frequency then there would only be one light to flash - so why five leds?
Do they show a rising rate of knock events at one freq. or does each led correspond to slightly different freqs around the main expected knock freq?

Nick

 

Does that mean you have to use these everytime you drive your vehicle? I don't have a KL yet but I would have thought it'd be a little bit more practical for the every day driver like myself.

 

All the LED's correspond to the same frequency, just the more lights the more knock (they show the volume/amplitude). So yes they show a rising rate of knock.

 

**** the bed that Daveys a **** eh?