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Knock Sensor Question


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#1 81zfan

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Posted 22 July 2019 - 09:06 AM

From everything I've searched and read on here concerning this, it's pointing toward the knock sensor being faulty.
Timing is set to 10BTDC with the Vac advance unhooked and the motor warm.
I can unplug the Knock sensor and watch the timing and it doesn't retard any, it doesn't change with or without the Knock sensor harness plugged in.
It stays at a steady 10 degrees with the Vac unhooked and advances with the Vac plugged up while revving.
I just want someone to confirm my suspicion as to the Knock sensor being faulty.
Also, I've hunted for one several different times and cannot find a stock one. Can anyone confirm that the 1g DSM knock sensors work with our motors?
88 conquest, .30 over block,Bs eliminated, M28 head ,17c turbo,Ottowerks shifter bushing, Lower Shores Braided lines and TB parts, Boostinmini TPS conversion kit,Optional Methanol Kit "when hooked up",Custom 2.5 Intercooler Piping,3 inch Downpipe, Gasket Ported Intake and Exhaust Manifold, Manual steering conversion,ACT HD clutch, Ebay knock off GReedy BOV,put car on a diet "lost between 590-620 lbs", Super AFC, AEM wideband, Glowshift Boost,Fuel Pressure, and Coolant Temp gauges, ARP Head and Rod bolts/Studs, Walbro 255.... In the process of adding more !





#2 TexasQuest

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Posted 22 July 2019 - 03:18 PM

The 1g DSM knock sensors will work if you cut and splice the SQ connector. They're also discontinued so you'll probably have to settle for a used one unfortunately.
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View PostJohnnyWadd, on 04 March 2010 - 10:01 PM, said:

my shaft was big i dont know what your talking about.

<SOS> http://sosmanuals.minagera.org/
<SQ Garage> http://www.starquestgarage.com/

#3 81zfan

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Posted 22 July 2019 - 03:25 PM

I've searched and searched. I found a stock replacement in Japan but it's looking like it could take a month to get here.
Am I right by thinking the timing should retard by unplugging the Knock sensor while running?
88 conquest, .30 over block,Bs eliminated, M28 head ,17c turbo,Ottowerks shifter bushing, Lower Shores Braided lines and TB parts, Boostinmini TPS conversion kit,Optional Methanol Kit "when hooked up",Custom 2.5 Intercooler Piping,3 inch Downpipe, Gasket Ported Intake and Exhaust Manifold, Manual steering conversion,ACT HD clutch, Ebay knock off GReedy BOV,put car on a diet "lost between 590-620 lbs", Super AFC, AEM wideband, Glowshift Boost,Fuel Pressure, and Coolant Temp gauges, ARP Head and Rod bolts/Studs, Walbro 255.... In the process of adding more !

#4 croquest87

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Posted 22 July 2019 - 05:03 PM

Knock sensor works in conjunction w knock box/ ignition control module. When knock sensor detects the sound/knock it sends electrical signal and retards to prevent motor from turning into a smoke machine or something in that order. Not sure that by just unplugging it is gonna net you any good. Perhaps you could tie it to a rubber hose some place where it can't hear anything  but yet still plugged in and try it. But it could be risky in case you really have a issue. I have never personally seen one go bad on these cars as crappy as they look.

Edited by croquest87, 22 July 2019 - 05:06 PM.


#5 81zfan

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Posted 23 July 2019 - 07:03 AM

I had read a few posts from years ago stating that by just unplugging it with it idling,the timing should retard at least 8 degrees if the sensor was working properly when it's unplugged.
I didn't know if there was a different test than the ones I was reading or if my sensor was indeed bad.
I'll keep searching and see if I can come up with any other test procedures.
I'll give your idea a shot too and see if it changes anything while at a idle.
I'm just trying to get the things I haven't checked out yet tested before I finally tag and insure it
88 conquest, .30 over block,Bs eliminated, M28 head ,17c turbo,Ottowerks shifter bushing, Lower Shores Braided lines and TB parts, Boostinmini TPS conversion kit,Optional Methanol Kit "when hooked up",Custom 2.5 Intercooler Piping,3 inch Downpipe, Gasket Ported Intake and Exhaust Manifold, Manual steering conversion,ACT HD clutch, Ebay knock off GReedy BOV,put car on a diet "lost between 590-620 lbs", Super AFC, AEM wideband, Glowshift Boost,Fuel Pressure, and Coolant Temp gauges, ARP Head and Rod bolts/Studs, Walbro 255.... In the process of adding more !

#6 mikec

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Posted 24 July 2019 - 12:24 AM

The factory service manuals do state that ignition timing should be retarded quite a bit if the ignitor module can't detect the knock sensor.  I recall unplugging the knock sensor on my car once as a test while the engine idled and I didn't see any change.  I suspect the ignitor only looks for the knock sensor when the main ECU tells it "boost pressure is present, start monitoring for knock."  On the factory dash vacuum/boost gauge, the boost (and some low vacuum) region is "filled in" on the arc.  When the needle is in that filled-in region, a signal is sent by the ECU to the ignitor to tell it to start monitoring for knock.  When the needle is in the hollow "vacuum" end of the arc, the ECU tells the ignitor to ignore knock sensor output.  That way the ignitor won't detect "knock" from a rookie/klutzy stick-shift driver that lugs the engine trying to pull out from a stop.  The engine is already about to stall thanks to that lousy clutch + throttle operation and is shaking as a result... if the ignition timing were to be retarded at this point the engine power would drop a lot - pretty much guaranteeing a stall.  Only when boost is present (which means the engine is well away from idle power) will the ECU and ignitor work together to retard timing if knock is detected.  As I said, I'll bet that's when the ignitor does the "is the knock sensor working?" test too.

So don't worry that you see no change in idle or ignition timing at idle RPMs when unplugging the sensor.  StarQuests don't use the knock sensor to "learn" either - i.e. they don't tweak ignition timing continuously to determine how much advance is possible based on the octane and quality of whatever gas you happen to be using at the moment.  Most cars today do this but not StarQuests.

mike c.

#7 81zfan

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Posted 24 July 2019 - 07:10 AM

I appreciate the answer Mike.  I was getting the info from a conversation that you, shelby and indiana had participated in a long time ago and this confirms again what I read.
The sensor I put in this motor was rough looking but that's all I had at the time,so I refilled it and crossed my fingers.
I'll check the resistance on this one and see if it's in range before I continue looking for a replacement. Again, thanks a million!
88 conquest, .30 over block,Bs eliminated, M28 head ,17c turbo,Ottowerks shifter bushing, Lower Shores Braided lines and TB parts, Boostinmini TPS conversion kit,Optional Methanol Kit "when hooked up",Custom 2.5 Intercooler Piping,3 inch Downpipe, Gasket Ported Intake and Exhaust Manifold, Manual steering conversion,ACT HD clutch, Ebay knock off GReedy BOV,put car on a diet "lost between 590-620 lbs", Super AFC, AEM wideband, Glowshift Boost,Fuel Pressure, and Coolant Temp gauges, ARP Head and Rod bolts/Studs, Walbro 255.... In the process of adding more !




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