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-   -   Knock Links. Caution. (https://www.scoobynet.com/general-technical-10/340796-knock-links-caution.html)

markwild 05 July 2004 09:12 PM

RichieD - Actually tap the top of the sensor.......

Mark

WUZ 06 July 2004 10:10 AM

:-(
 
Not had any problems with any that I have been supplied with through the group buy, but if there are any problems with them, PM me and I'll sort it out or give you the details of the company who supplied them.

I cannot be held responsible for the LED's not being soldered proberly onto the board. This is the responsability of Link Electrosystems in New Zealand.

But I will sort out any little niggles I can.

Russell

RichieD 06 July 2004 06:08 PM


Originally Posted by markwild
RichieD - Actually tap the top of the sensor.......

Mark

Hmm...
Just took a F*ing big screwdriver and tapeed the sensor.. managed to get all the LEDs to light.. but only with what I would call extreme abuse! - all with the sensitivity on max! (I did try with sensitivity all the other way round.. and got only one green LED for the same abuse).

Surely this can't be right?! - with the amount of knocking required to get the LEDs to light.. it makes me wonder why I bothered at all with the knocklink... I can feel the knocking required to get the damn thing to react!

markwild 06 July 2004 07:25 PM

Don't forget that it isn't listening for hammer blows ;)

Only the right frequency.. so a 'tap' didn't cut it with mine (I used the rachet drive handle...)

The 'tap' technique isn't really generating the right noises, but will do as a test....

Sounds OK to me...

Mark

micared 06 July 2004 10:34 PM

Just gone and tried mine in a panic and all o.k, for the mo, anyway. Btw, the leds on mine are remote mounted ( got the local telly repair man to do the soldering ), and the sensor on mine only requires what I would call a very light tap with a 14mm socket on an extension bar to light all leds. I only ever get one bright green while driving ( MY00 Bob Rawle tek3 ), so would suggest that anything heavier than this to light them up is pointing to your KL giving you suspect info! Might be that the quality of soldering on some modified KLs is better than standard, requiring less of a thump to activate it.

GREEN SCOOBY 07 July 2004 12:10 AM

I always wanted one of these and was considering buying one but with this amount of problems it sounds like the oe subaru one if it is working or not is just as reliable. Time to think about this. Harvey,how is the new engine working out mate?

Jasoon 12 July 2004 07:52 PM

What sensitivity do the knock come set to?

I can get the first green led to light up bright using a screwdriver tapping it on the top of the bolt holding the sensor cant really try it too hard as im having to thread the screwdriver in by the intercooler.

Jasoon 12 July 2004 08:36 PM

To test the led's are working can you not just un-plug the connector to the sensor and short it out making the knocklink think its picking up loads of noise?

cw42 13 July 2004 12:25 AM

After visiting Bob Rawle on saturday for my remap :), I was recommended getting a knocklink, now I'm not so sure :(
What is the point if they are not working properly? Is anyone in a position to make and market there own version? Surely with a circuit diagram, and a visit to maplins :) someone with a bit of electrical nouse could "knock" one up (sorry:))
What is the oe subaru one like, and how much is that?
chris.

Jasoon 13 July 2004 07:14 AM

The problem with the led's should be easy to test and fix.

MY99-5DR 13 July 2004 08:57 AM

Excuse my ignorance and all, but what is the main gripe with the standard car setup?

No LED's granted, but is it that the OEM sensor is $h!te, or is the signal from it not used to good effect by the ECU? If the sensor is the weak link in the chain, could it be exchanged for something more sensitive/robust, etc.? If it's the way the ECU interprets the data, is there anything that could be done to sort that at a remap?!

Does seem a bit of a high-risk strategy to place all your faith in a box of lights that could have come from a Kwik Save christmas cracker???!

markwild 13 July 2004 09:26 AM

The OEM system is fine I guess - except that the signal is fed to the ECU, which can back off the ignition timing - but only to a certain degree.

The problem with modifications is that you are closing the safety limit - therefore, the ECU can do less to avoid a disaster.

The KL is really a way of informing the ultimate controller (the driver) that all is not well - for example, heat soak has occurred with a TMIC on a hot day in traffic. The stock ECU on a stock car will be able to cater for this, but if you;ve mapped the ECU to advance the ignition, you've effectively reduced the amount it can be retarded.

I think that you are right wrt a re-map, and it probably should cater for it - but wouldn't you like to know that gunning it at a certain time is causing ignition retardation ?

For example, I've happily used my car since a remap, showing 2 greens at 4-5k in the rev range in 3rd for 6 months - I'm aware that it would be 'better' if no lights are shown, but if this were done simply by reducing ignition timing (for example), then I'd get less power - better to know its happening and find a better solution, such as reducing charge temps at this range....

Mark

The_Judge 13 July 2004 10:16 AM

Also don't forget that the stock knock sensor stops listening above a certain engine speed. So if you've made modifications, and you're red-lining every gear, if the engine starts to det, the only way you're gonna save a piston from melting is by taking your foot off the loud pedal, finding out why it's detting, and sorting it out. Without the Knocklink, how are you going to know if it's detting or not? Yes, det is audible, but at revs of say 5000rpm, are you confident you can tell det from engine noise? Especially when you consider the stock knock sensor can't, hence the need for the Knocklink...

It probably isn't a crucial purchase for someone with a standard or modestly modded UK car. But anyone who's tatted with boost levels, or anyone with a JDM, should make it a priority. And as to "this amount of problems", I think this thread relates to an unfortunate minority of Knocklink owners, certainly not the majority...

WRX_Rich 13 July 2004 10:56 AM

if you have ever had a dodgy batch of optimax you can sure tell with a knocklink :)

markwild 13 July 2004 11:00 AM

I'd certainly second the view that not all kls are bad - mine's been fine for over a year.....

Mark

MY99-5DR 13 July 2004 11:10 AM


Originally Posted by The_Judge
Also don't forget that the stock knock sensor stops listening above a certain engine speed.

I have read elsewhere that the knock sensor stops reading at 5500rpm as you have eluded to, but I would perceive that as a failing of the standard system?

Is it the case that the standard sensor can't discriminate between normal running frequencies (& their harmonics) versus detonation frequencies at these engine speeds - leading the ECU to be programmed to ignore the signal completely, or is it something else?

Please forgive my ignorance, but as a newcomer to Scoobs, I just find it odd that having driven a variety of cars including Golf GTi's, a Porsche Boxster S and a MKIV twin turbo Supra I haven't previously experienced such apprehension over a car's basic ability to monitor and eliminate detonation.

Sorry to be such an anorak, I'm just interested to better understand the standard system to see if there is any scope for engineering a more permanent improvement

The_Judge 13 July 2004 12:34 PM


I have read elsewhere that the knock sensor stops reading at 5500rpm as you have eluded to, but I would perceive that as a failing of the standard system? Is it the case that the standard sensor can't discriminate between normal running frequencies (& their harmonics) versus detonation frequencies at these engine speeds - leading the ECU to be programmed to ignore the signal completely, or is it something else?
Unfortunately, detonation happens at the frequency it happens at, and the knock sensor simply isn't capable of distinguishing between det and engine noise at those revs. If it didn't stop listening, every time you took the revs to the red line, you'd probably find the ECU would retard the timing as far as it could, and would probably end up putting the car into limp home mode, just in case, making the car undrivable above a certain rpm. In which case, you might as well bring the red line down to that rpm...


I haven't previously experienced such apprehension over a car's basic ability to monitor and eliminate detonation.
Were all of your previous cars modified, or standard? And were any of them imported?

The standard system works fine on a standard engine. The fact that the sensor stops listening above 5500rpm (if that's the level) isn't really a problem on a standard car, as the timing and boost maps are perfectly safe with standard boost levels.


I'm just interested to better understand the standard system to see if there is any scope for engineering a more permanent improvement
If engines could be made to run quieter, if detonation occurred at a different frequency, or if it didn't exist... any of those would help :)

markwild 13 July 2004 01:09 PM

I guess a better solution would be an improved sensor - like the bosch one on the KL, that can listen at high revs, that feeds to an ECU that does react at those revs

i.e. rather like the KL feeds the drivers brain ( ;) ) - Not sure if any of the aftermarket ECUs are capable of this >?

Mark

The_Judge 13 July 2004 02:15 PM

The Bosch sensor also picks up engine noise though (although not to the same degree as the stock sensor)... :(

markwild 13 July 2004 02:43 PM

True - hence the gear change flicker I guess ;)

Jasoon 13 July 2004 03:27 PM

I think its a case of a number of engines have gone band due to detonation so its better to be safe than sorry.
in my case I could have not bothered about fitting a knocklink as I've got plenty of warranty left on my car so the garage would have to fix the car under warranty ,but I would prefer to had the knocklink and possibly save the hassle of my engine going bang.

I must admit that if someone could come up with a nicer looking box for the knocklink ,I think they would be on to a winner.

MY99-5DR 13 July 2004 04:07 PM

Has anyone ever tried mating the better Bosch sensor directly with the factory ECU?

The_Judge 13 July 2004 04:26 PM

Assuming the ECU could be told to listen throughout the entire rev range, you'd still have the same problem, although maybe not to the same extent...


The Bosch sensor also picks up engine noise though (although not to the same degree as the stock sensor)...

RaymondH 04 August 2004 08:19 PM

BTT for those who haven't checked their Knock Links yet... I did mine today and couldn't light the red. I removed and opened the box and the red diode was wobbling around all over the place :mad: My local TV repair man soon resoldered it and did the others as well because they looked dry too. I'm not very happy because I've seen two ambers a few times and now wonder if the red should have been on too :( I hope their ecu's are better made than their Knock Links...

Incidentally, I placed a 3/8 extension bar on the mic bolt and didn't have to tap it very hard at all with a small hammer to light up everything.


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