# Removing knock sensor control unit



## scirocco25 (Aug 22, 2004)

*Removing knock sensor control unit (Megasquirt content)*

This is for a PL 1.8L 16v motor. 
I am removing all my CIS-E and converting to Megasquirt(fueling only). I am keeping the stock VW ignition. I am also converting to ITB's, so I will not have the TB idle/WOT switches. I don't need the knock box to control the fuel pump relay, I will have an external relay for the pump. Is there any reason to keep the knock box? What would it entail to remove it? I see that the hall sender is routed thru the knock sensor control unit (correct?), but everything else on the knock box is expendable, IMO. 
Is this something I want to do? Is it necessary given that I dont have the TB switches? Or will it not work? I'm guessing that I want to remove the whole knock system given my setup. 


_Modified by scirocco25 at 5:18 PM 5-13-2009_


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## need_a_VR6 (May 19, 1999)

*Re: Removing knock sensor control unit (scirocco25)*

Just ditch all of it and give the MS control of the timing entirely. It's almost easier to do it that way!


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## scirocco25 (Aug 22, 2004)

Nope, gotta keep it.


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## need_a_VR6 (May 19, 1999)

*Re: (scirocco25)*

Race rules?


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## scirocco25 (Aug 22, 2004)

My rules. I don't want to set up spark control on MS. I have enough to worry about getting the fuel map sorted out. I could be convinced later on, but for now MS will be fuel only.


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## VW_tayder (Oct 4, 2005)

*Re: (scirocco25)*

_Modified by VW_tayder at 8:19 PM 5-11-2009_


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## Subnormyle (Aug 30, 2005)

*Re: (scirocco25)*

I did the same thing on my MS install. Check out the Knock Box Write Up here.
http://www.driversfound.com/scirocco/ 
You need to retain the Knock Box if you want to retain stock ignition and not use MS to control it. The Knock Box stores the timing map and controls advance/retard of your ignition system. Without it you will have static timing. I would figure out a way to rig up WOT/Idle switches to your ITB setup if you plan on running stock ignition.


_Modified by Subnormyle at 10:24 PM 5-11-2009_


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## scirocco25 (Aug 22, 2004)

I'm starting to get a handle on what will be required. It seems like I can re-route the wires from the hall sensor to the knock sensor box, so that power and ground to the hall sensor are directly fed, and then connect the green wire to pin 6 on the ICM. This should bypass the knock box. 
The only issue I think is that the knock box provides some timing shift, which will need to be compensated for by adjusting the spark timing at the distributor now that the knock sensor control has been eliminated.
Anyone have tips?


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## scirocco25 (Aug 22, 2004)

*Re: (Subnormyle)*

I was under the impression that the ICM contained the ignition map and that the knock sensor control just provided the ability to retard the timing upon sensing knock?


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## B4S (Apr 16, 2003)

*FV-QR*

Nope, the CIS-E knockbox setup IS the ignition control. The ICM is simply an external ignitor for the coil, it still needs to be told when to charge the coil.


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## need_a_VR6 (May 19, 1999)

*Re: FV-QR (B4S)*

Exactly, the knock box is a full 'timing computer.' The ignition module only takes care of dwell control.


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## epjetta (Sep 19, 2006)

*Re: (scirocco25)*

seriously. just hook it up through MS. you will be happy you did after you have it running and WANT control of the spark.


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## chois (May 12, 2000)

As mentioned the knock box determines the timing curve. I will be letting MS control my spark, but use a bosch ICM to provide appropriate dwell, and use stock everything else in the ignition system.


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## scirocco25 (Aug 22, 2004)

Before I dig thru about 10,000 MSn'S threads, how much work is it to get the stock 16v distributor/hall sensor to trigger MS? I have a couple years old MS box v2.2. I'm going to assume I need to reflash to whatever the newest version is, plus do some ridiculous mods to the PCB? 
Sorry if that sounds assholish, its just all day long I hear people asking how the hell to get the n'Spark portion working right. I don't have as much patience with the soldering iron at this point.
On a side note, what about just going to a Saab 900 distributor and running vacuum advance, and triggering off the coil?


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## chois (May 12, 2000)

I know that triggering off the hall is easy with MS2, and would imagine it is with MSnS as well. There used to be a really good thread on the subject over in the 16v forums.
Yeah the vacuum distro would work too, just make sure you use the appropriate ICM to get the right dwell.


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## scirocco25 (Aug 22, 2004)

Digging around a little bit, it seems like it wouldnt be too hard to modify for spark control. Seems that the board mod is so that you get positive voltage from the hall sensor when it triggers, as opposed to grounding.


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## need_a_VR6 (May 19, 1999)

*Re: (scirocco25)*

It's actually really easy, just mod it for 5v low to high hall from the hardware manual, as well as the LED circuit mods to drive the ICM. I've used that circuit in 30ish ecu's.


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## scirocco25 (Aug 22, 2004)

*Re: (need_a_VR6)*

Yea, I've done some quick research and found a couple diagrams. I pretty much understand the general idea of what I need to do. Reflash with MSnS-E, perform the jumpers and other mods, and then rewire the hall and ICM. I like the mod that runs +5v to the hall, that seems to be the cleanest signal and eliminates any interference from the 12v system.
Is this the correct diagram?









Another diagram that seems to be better is this one:










_Modified by scirocco25 at 8:51 PM 5-12-2009_


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## need_a_VR6 (May 19, 1999)

*Re: (scirocco25)*

I use the first one. I use TPSVref for the 5v feed to the hall with no resistor. 
The second diagram of mods is the 'old' way of doing things, it moves hall input to pin 25, and uses up one of the spare pins this way.


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## scirocco25 (Aug 22, 2004)

OK, so with the top diagram, which pin is the output to the Bosch ICM? It would appear to be pin 25. 


_Modified by scirocco25 at 6:47 AM 5-13-2009_


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## need_a_VR6 (May 19, 1999)

*Re: (scirocco25)*

The top diagram doesn't show the output mod:








That puts spark output on Pin25. I have used 1k for the resistor value for a LONG time as well, but 750ohms works.


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## scirocco25 (Aug 22, 2004)

*Re: (need_a_VR6)*

I made an image of the mods to the board for both 5v hall trigger mod, and spark output mod. Does everything look OK? Its alot easier to figure this out on paper first rather than try to fix it once its been screwed up.


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## need_a_VR6 (May 19, 1999)

*Re: (scirocco25)*

Looks right to me.


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## Salsa GTI (Aug 29, 2000)

*Re: (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_Looks right to me.

And you would know http://****************.com/smile/emthup.gif 
Follow Pauls advice and you will never go wrong.....
Well except for map tuning on an ITB setup....thats where I agree to disagree


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## need_a_VR6 (May 19, 1999)

*Re: (Salsa GTI)*

There are many ways to do things, a right way, a wrong way and my way, which is the right way.


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## Salsa GTI (Aug 29, 2000)

*Re: (need_a_VR6)*

True








And i like Megatune better than some other user interfaces....
and managed to pop my head gasget between 3&4...perhaps somthing better than stacked gasgets this time...or tune it on stock compression










_Modified by Salsa GTI at 9:09 AM 5-15-2009_


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## need_a_VR6 (May 19, 1999)

*Re: (Salsa GTI)*

I've been using Tunerstudio lately and that's better then, well even more interfaces.
Go stock comp and use real gas.


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## Salsa GTI (Aug 29, 2000)

*Re: (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_I've been using Tunerstudio lately and that's better then, well even more interfaces.
Go stock comp and use real gas.









No...
Its a street car silly..
Need Low comp and 93 oct








Tuner studio is compatible with what?
Megasquirt?


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## MidnightunersVaUS (Aug 29, 2008)

Hey guys i have a question for ya i have ke-jetronic on my 87 16v i put ms on it a few years ago i have been useing the stock knock box to control spark and ms to control fuel well i want to leave the stock spark on there but i want to pull the stock jetronic computer out all the way can i just pull the thing out and clean up the wireing or what do i have to do by the way i pulled the full trottle switchs off a long time ago when i put ms on and have not had a problem with anything so whats the deal on that???


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## ABA Scirocco (May 30, 2001)

*Re: (MidnightunersVaUS)*

I've never quite been able to figure out what the knock box does with the WOT switch either. When I had a KS system on my previous Scirocco, disconnecting the WOT switch made no discernible to the way the engine performed. As best as I can figure, it probably reduces the knock sensitivity of the system a little bit at WOT so unless you're getting some significant knock at WOT, it won't make a difference. 
As far as eliminating the KS system, go for it, just be a little conservative on the ignition timing when you first tune it then get more aggressive in small steps until you learn how much your timing your engine likes and how much it will tolerate without knocking.


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## B4S (Apr 16, 2003)

*FV-QR*

I think you're right, I believe it either starts to filter out valve train noise at a much more aggressive rate, or shuts it off completely.


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