Ian C Posted January 7, 2002 Share Posted January 7, 2002 I hear that the MkIV has a pair of knock sensors - where are they located in the engine bay and how do they work? Do they report an analogue voltage depending on the severity of the knock, or is it an on/off affair? -Ian Quote Link to comment Share on other sites More sharing options...
GavinL Posted January 7, 2002 Share Posted January 7, 2002 Where is Ash ? ....this is his sort of question Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted January 7, 2002 Share Posted January 7, 2002 I think they are the same place as the MKIII, two of them just under the inlet manifold. As far as i know they are a type of piezo sensor giving a rising output for an increase in knock, or occasionaly other engine noises. Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted January 7, 2002 Share Posted January 7, 2002 Quote: from GavinL on 9:09 am on Jan. 7, 2002[br]Where is Ash ? ....this is his sort of question Who cares!!! Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 7, 2002 Author Share Posted January 7, 2002 The reason I ask is that wouldn't it be possible to wire up a couple of lights on the dash to said knock sensors, and then you know when they are detecting knock? I mean, it would react quicker than EGTs or an AF meter... -Ian Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted January 7, 2002 Share Posted January 7, 2002 I think you could probably still wire up something (devices are commercially available) it would just depend on what sort of display you were after and what you hope to obtain from the project. A certain amount of knock will be present when the ECU re-learns for new fuel, changes in conditions, etc. Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 8, 2002 Author Share Posted January 8, 2002 What I hope to obtain from the project is me never blowing the engine up again! All I would want was a big red light that lit up every time the knock sensor registered a hit. OK, rolling around town post-ECU reset wouldn't scare me that much, but hitting 165mph and suddenly getting the light flash would make me lift off immediately and save £4,500 ish quid... Whaddya think, am I missing a big thing here or is it a very simple, very useful thing to do? -Ian Quote Link to comment Share on other sites More sharing options...
GavinL Posted January 8, 2002 Share Posted January 8, 2002 Ian Sounds like a very simple idea but begs the question why don't the likes of HKS produce something to this effect. Quote Link to comment Share on other sites More sharing options...
Digsy Posted January 8, 2002 Share Posted January 8, 2002 When we are doing spark mapping, we usually have a guy sat running the test cell with a pair of headphones on and an oscillascope hooked up to the knock sensor, and the spark advance dial in his hand. He runs the engine up to a specific speed and then dials in the spark until the engine starts to knock. He literally listens and watches for the onset of knock and dials out the spark when it happens. I'm not sure what signal pre-processing goes on between the sensor and the oscillascope / headphones though... Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 8, 2002 Author Share Posted January 8, 2002 Well, it seems to be a plan with no drawbacks. I'm not saying it would assist in diagnosing any problems with the engine or fuelling like say an AF meter or an EGT gauge would (both of which I am investigating anyway - I'm serious about not destroying another engine...), but as an instant 'lift off or die' warning you aren't going to get anything faster than a light connected to the knock sensor! Ok, you may need a bit of electronics to invert or threshold or filter the signal (did that sound like I knew what I was on about? Thought not...) but it's still not going to be very expensive for such a potential ar5e-saving device. If there is nothing commercial out there to do this, I claim copyright and all that so I can make a fortune out of it and build a really really big Supra and buy a Zonda C12 as well and live happily ever after. So there. -Ian Quote Link to comment Share on other sites More sharing options...
Lee Burley Posted January 8, 2002 Share Posted January 8, 2002 Quote: from Ian C on 3:37 pm on Jan. 8, 2002[br]Well, it seems to be a plan with no drawbacks. I'm not saying it would assist in diagnosing any problems with the engine or fuelling like say an AF meter or an EGT gauge would (both of which I am investigating anyway - I'm serious about not destroying another engine...), but as an instant 'lift off or die' warning you aren't going to get anything faster than a light connected to the knock sensor! Ok, you may need a bit of electronics to invert or threshold or filter the signal (did that sound like I knew what I was on about? Thought not...) but it's still not going to be very expensive for such a potential ar5e-saving device. If there is nothing commercial out there to do this, I claim copyright and all that so I can make a fortune out of it and build a really really big Supra and buy a Zonda C12 as well and live happily ever after. So there. -Ian Maybe you could sense that if speed>certain threshold and the output from the knock sensor goes off a certain number of times or EGT gets too high then you start cutting sparks or whatever. The temptation to stay on the throttle when the little red lights come on is too much for some people - like Justin for example..... :-) Quote Link to comment Share on other sites More sharing options...
Digsy Posted January 8, 2002 Share Posted January 8, 2002 Quote: from Lee Burley on 4:01 pm on Jan. 8, 2002[br]Maybe you could sense that if speed>certain threshold and the output from the knock sensor goes off a certain number of times or EGT gets too high then you start cutting sparks or whatever. The temptation to stay on the throttle when the little red lights come on is too much for some people - like Justin for example..... :-) Thats what the inbuilt knock control tries to do. Trouble is you have to build a little intelligence into it, and Ian's car is way to mad for that! Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 8, 2002 Author Share Posted January 8, 2002 It's a valid idea. I was thinking of a fairly unsubtle sudden and dramatic power loss, and I realised I had finally found a use for the stock traction control! I would say version 1 should be a light on the dash, version 2 would initiate spark cut or stock trac as well as the light on the dash. Version 3 would be branded by a tuning company and cost 10 times as much as version 2 I'm sure Justin wouldn't be keeping his foot down in such a scenario, though, as I know he's suffered some rather expensive engine damage before as well - I know I wouldn't ignore it knowing what could happen!! His just took longer to manifest itself, so watch out all you overboosters out there... -Ian Quote Link to comment Share on other sites More sharing options...
Phil Wall Posted January 9, 2002 Share Posted January 9, 2002 Quote: from Martin F on 11:32 am on Jan. 7, 2002[br] I think they are the same place as the MKIII, two of them just under the inlet manifold. As far as i know they are a type of piezo sensor giving a rising output for an increase in knock, or occasionaly other engine noises. As above loacated roughly between cylinders 1&2 and 5&6 Quote Link to comment Share on other sites More sharing options...
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