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Discussion Starter · #1 · (Edited)
Okay, so since I installed my engine, I've been having TPS and MAP issues. I fixed the MAP sensor awhile back which raised my alarming 9 mpg to about 23. Then today I decided to fix my TPS problem. It wasn't really affecting much and I never knew how to do it but researched calibration and now its all working fine. Then I proceeded to change my spark plugs because she's been feeling a tad on the sluggish side lately. I took her out for a test run. FINALLY! No check engine light in the corner of my eye, what a relief. Wait a second... NO! I pull over to check the light pulling out my handy paperclip. This time... It's reading code 23. I've never had this code pop up and if my sources are correct, it is my knock sensor. When I turn the car off the code stays away until about 3rd gear when I let of the clutch or so. I've never had this code before and it is running strong as ever. Any ideas?

I'm running 93 Octane on a JDM h22a and Iridium IX plugs.

The only thing I can think of is the plug(s) are bad that I just installed or maybe one of them may have gotten messed up when I was installing them. My friend doesn't have a 5/8 with rubber grommet so they were pretty much just dropping straight down and their gaps might have been altered.
 

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code 23 is defined as:
(Knock Sensor)
defective circuit or unplugged / defective sensor

the knock sensor is easy to damage when swapping a motor in or out, or pulling/installing a head.
check to make sure its even plugged in. also check for damage to the wire going to it, and for damage to the sensor itsself.

its also possible that your ignition timing is not set correctly; if it's too far off it will actually think something is wrong with the knock sensor. if the distributor is too far retarded, the engine will never knock, and the ecu will think the sensor is bad or unplugged due to never receiving a knock signal. if the distributor is too far advanced, it will be knocking practically constantly, and the ecu will think either the knock sensor is bad or there is a wiring problem causing an intermittent signal more than it should be.
 

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Discussion Starter · #3 ·
code 23 is defined as:
(Knock Sensor)
defective circuit or unplugged / defective sensor

the knock sensor is easy to damage when swapping a motor in or out, or pulling/installing a head.
check to make sure its even plugged in. also check for damage to the wire going to it, and for damage to the sensor itsself.

its also possible that your ignition timing is not set correctly; if it's too far off it will actually think something is wrong with the knock sensor. if the distributor is too far retarded, the engine will never knock, and the ecu will think the sensor is bad or unplugged due to never receiving a knock signal. if the distributor is too far advanced, it will be knocking practically constantly, and the ecu will think either the knock sensor is bad or there is a wiring problem causing an intermittent signal more than it should be.
well a defective circuit would mean that it is reading properly. it causes the defective circuit when it reads the knock by sending a different voltage to the ecu right? or am i completely wrong here and it is just the sensor malfunctioning. the only reason i say this, is because it hasn't been reading knock sensor once since i put the engine in almost a year ago until tonight when i fixed the tps and changed the plugs.
 

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well a defective circuit would mean that it is reading properly. it causes the defective circuit when it reads the knock by sending a different voltage to the ecu right? or am i completely wrong here and it is just the sensor malfunctioning. the only reason i say this, is because it hasn't been reading knock sensor once since i put the engine in almost a year ago until tonight when i fixed the tps and changed the plugs.
lmao, waaaaay off base here haha.
for starters, map issues and tps issues both throw the ecu into limp mode, where it ignores the map sensor and tps sensor and knock sensor and o2 sensor, and runs strictly according to a pre-programmed "safety" map and the temp sensors. so the ecu was never looking for the knock sensor while you had those other issues, so it never would have thrown a code.

and the word defective means broken in some way shape or form, aka not working properly, lol.
so a defective circuit would mean that there IS a problem and that it is NOT reading properly.

go back and read what i said.
its either a problem with the sensor itsself, or the sensor is unplugged, or there is a problem somewhere in the wiring for the knock sensor.
 

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Discussion Starter · #8 · (Edited)
Oh well after driving it again I noticed that the CEL does not arrive until after the car has warmed up all of the way. I do not notice any timing change or any knocks for that matter. The engine coolant temp gauge is normal as usual so I don't know what's up. So tomorrow I suppose I will test the knock sensor. Is there a voltage reading I should look for or anything like that?
 

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Oh well after driving it again I noticed that the CEL does not arrive until after the car has warmed up all of the way. I do not notice any timing change or any knocks for that matter. The engine coolant temp gauge is normal as usual so I don't know what's up. So tomorrow I suppose I will test the knock sensor. Is there a voltage reading I should look for or anything like that?
even if it was working you wouldnt notice anything in regards to timing changing. but of course because its getting a cel it definitely isnt altering the timing at all.
and it doesnt appear until its warmed up because the ecu doesnt start using the knock sensor until the car is fully warmed up.
there's no voltage reading to look for, just check the wiring and plug and sensor for visual damage. i think there is a resistance test you can do on the knock sensor, but i dont know what the resistance is supposed to be
 

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Discussion Starter · #10 ·
Well it all makes sense now and luckily I have a spare knock sensor from my last motor. This one was in horrible condition when I got it, but thats what I get for finding one for $1000 you get what you pay for.
 

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in case you or anyone else is wondering, i have a near brand new knock sensor for sale for all 92-96 preludes and all 92-01 integra's. $50 shipped. its less than a year old genuine oem honda, and has less than 3k miles on it. i have a thread in the for sale section for it
 

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Discussion Starter · #13 ·
Well I actually have an aftermarket ECU that deletes the knock sensor anyways but it runs really rich so for fuel purposes I use my stock ECU.
 

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Well I actually have an aftermarket ECU that deletes the knock sensor anyways but it runs really rich so for fuel purposes I use my stock ECU.
then why dont you just go get the car tuned if you already have a tuneable ecu. or is it a fake chipped ecu that isnt even tuneable? lol
 

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Discussion Starter · #15 ·
then why dont you just go get the car tuned if you already have a tuneable ecu. or is it a fake chipped ecu that isnt even tuneable? lol
It already has a decent tune on it that creates a considerable amount of difference in power. But basically the reason would be associated with $$$$$. Not too worried about it right now.
 
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