questtuner82 Posted November 10, 2014 Report Share Posted November 10, 2014 Ok so im trying to find out if there are any knock sensors that can be used with our cars as a factory replacement for a stock computer setup still running oem dizzy and oem tbi. Link to comment Share on other sites More sharing options...
ucw458 Posted November 10, 2014 Report Share Posted November 10, 2014 DSMs use the same sensor with a different plug. If the OEM SQ sensor isn't available then try getting the DSM one. You can't just plug another manufacturers sensor into a SQ. The voltages are different. A knock sensor is just a peizo element that produces a voltage based on the amount of vibration it's exposed to. The higher the vibration the higher the voltage. Knocking creates significantly higher vibration so you get more voltage. ECUs are set to ignore a certain voltage threshold. Lets say normal engine operation generates 1 volt and a knock will generate 1.5-2 volts. The ECU will ignore any voltage around 1.2 volts or less. Stock SQ knock sensors generate a maximum voltage of around 0.5 volts. So if you substituted a knock sensor from a nissan SR20 motor, (very common sensor used on alot of cars and different motors) your stock SQ ECU will think it's hearing knock 100% of the time. The SR20 sensor has a max output of around 2 volts with a nominal voltage on a running G54B of around 1 volt. I know this because I use the SR20 sensor on my MPI. The standalone allows me to set the voltage threshold. The SR20 sensor is needed because the stock SQ sensor doesn't put out enough voltage for my standalone to detect. 1 Link to comment Share on other sites More sharing options...
mstieg Posted November 10, 2014 Report Share Posted November 10, 2014 I was just asking this exact question for my setup. Which year SR20 sensor are you rolling with? Any issues with false knock reporting? Assume your balance shafts are gone? Any other relevant factors? Link to comment Share on other sites More sharing options...
ucw458 Posted November 10, 2014 Report Share Posted November 10, 2014 Just search for nissan SR20 knock sensor. That sensor came on MANY cars not just nissans. No balance shafts. As far as false knock,.... you have to set the voltage threshold in your ECU. Datalog a full boost run and that will give you the nominal backgound voltage. The stock sensor has a m10x1.25 connection. The nissan sensor can only accept up to a m8 bolt. http://i463.photobucket.com/albums/qq352/ucw458/Knock%20Sensor/DSC03918.jpg I didn't want to remove a bunch of stuff then put a bolt in the stock location, cut it off and grind it smooth then tap for m8. That would be too much work. So I modified an broken stocksensor to make an adapter. http://i463.photobucket.com/albums/qq352/ucw458/Knock%20Sensor/DSC03919.jpg After cleaning it out I melted some aluminum and casted it inside the sensor body. http://i463.photobucket.com/albums/qq352/ucw458/Knock%20Sensor/DSC03920.jpghttp://i463.photobucket.com/albums/qq352/ucw458/Knock%20Sensor/DSC03921.jpg After casting I drilled and tapped the stock housing for a m6 bolt. Then belt sanded the mating surface flat. http://i463.photobucket.com/albums/qq352/ucw458/Knock%20Sensor/DSC03922.jpghttp://i463.photobucket.com/albums/qq352/ucw458/Knock%20Sensor/DSC03923.jpg This is what I ended up with. A perfect adapter. http://i463.photobucket.com/albums/qq352/ucw458/Knock%20Sensor/DSC03926.jpg Link to comment Share on other sites More sharing options...
TexasQuest Posted November 11, 2014 Report Share Posted November 11, 2014 Rockauto shows them to still be available new $123.00 Link to comment Share on other sites More sharing options...
mstieg Posted November 14, 2014 Report Share Posted November 14, 2014 Rockauto shows them to still be available new $123.00 Am I missing something or are these not available on the cheap ( < $10 ??) http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2051067.m570.l1313.TR10.TRC0.A0.H0.Xnissan+sr20+knock+sensor&_nkw=nissan+sr20+knock+sensor&_sacat=0 Link to comment Share on other sites More sharing options...
ucw458 Posted November 14, 2014 Report Share Posted November 14, 2014 Am I missing something or are these not available on the cheap ( http://www.ebay.com/...sensor&_sacat=0 He's talking about the OEM sensor. Link to comment Share on other sites More sharing options...
mstieg Posted November 14, 2014 Report Share Posted November 14, 2014 (edited) To clarify for home audience, ^ I'm looking SR20 (cheap, needs mod to fit) because I'm MPI with a higher mod build needing a different range of knock voltage. Other talk is about the stock setup & OEM sensor (pricey). Thanks. Edited November 16, 2014 by mstieg Link to comment Share on other sites More sharing options...
questtuner82 Posted November 16, 2014 Author Report Share Posted November 16, 2014 Ok so i got a 90 dsm knock sensor fits good. Got the plug and spliced solder the connection base timing is good and set at 10 btdc running 93 and car still has a spark knock. 18 psi stock motor stock turbo. Maft 3" mas 2.5" exhaust 2.25" hardpipes new and bigger b&p intercooler. RR FPR 41psi at idle. Just a narrowband right now. Pulls hard but wot it has a spark knock (predet) what has to be done bc ive ran my 383 stroker for my dirt track car on 87 a whole season with no issues and the 383 dynoed at 546hp with 87 Link to comment Share on other sites More sharing options...
psu_Crash Posted November 16, 2014 Report Share Posted November 16, 2014 Just fyi I bought a new mitsu knock sensor several (7ish) years back. It cost me $120 and I never used it since I went mpi at the same time. They aren't cheap Link to comment Share on other sites More sharing options...
ucw458 Posted November 16, 2014 Report Share Posted November 16, 2014 Ok so i got a 90 dsm knock sensor fits good. Got the plug and spliced solder the connection base timing is good and set at 10 btdc running 93 and car still has a spark knock. 18 psi stock motor stock turbo. Maft 3" mas 2.5" exhaust 2.25" hardpipes new and bigger b&p intercooler. RR FPR 41psi at idle. Just a narrowband right now. Pulls hard but wot it has a spark knock (predet) what has to be done bc ive ran my 383 stroker for my dirt track car on 87 a whole season with no issues and the 383 dynoed at 546hp with 87 First off a 383 is not a G54BT so whatever you did on that motor does not apply to a 2.6. The stock 12a is inefficient above about 10 psi. It will make more boost but it makes alot more heat doing it. Not only that but the stock hotside is a little small for those boost levels. What you need is a 16g with a TD06 wheel in the hotside. A turbo shop can put that stuff inside a stock turbo housing. You also need to port the manifold and turbo hotside. That will help your setup put out more power. If you care about your car you will stop boosting it to 18 psi until you get a wideband. Your setup may be leaning out and causing the knock. Your narrowband is junk and wont tell you squat about a lean condition. You could be pushing 12-13:1 which is motor blowing territory. Only a wideband will tell you that. Link to comment Share on other sites More sharing options...
TexasQuest Posted November 16, 2014 Report Share Posted November 16, 2014 Is the price of an oem one the reason people are searching for alternatives? Link to comment Share on other sites More sharing options...
markhansenconquest Posted November 16, 2014 Report Share Posted November 16, 2014 ^^^^same question ??? Link to comment Share on other sites More sharing options...
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