Recently I had a lil pow wow with a mustang and missed 3rd... About 2 minutes after my CEL come on and indicated a code 23/knock sensor.


Victim:
1995 Acura Integra GSR
B18C1
5 speed

Things I have tried:
Replaced KS torqued to spec 23ft lbs.
Substituted a known good ECU
Ran a parallel circuit from D3 @ the ECU to KS
confirmed perfect circuit from ECU to KS = .000 ohm
checked for stray AC voltage from the ALT.
no short to ground
no short to voltage
checked for RFI

Does anyone know the fail logic for code 23? All Data does not specify what logic or means of how the ECU tests the circuit.

Appreciate the help!

 

Yea, I know the fail logic, you damaged your motor and it's know knocking. The knock sensor then picks up on the knock, trips, sends the signal to your ECU, which then turns on your CEL. If you "missed" third, does that mean overrev/bent valves? Does the car run fine or does it run like crap due to the bent valves?

 

car runs fine.. 10% leakage on all 4 ( did a leakdown test that would have indicated more leakage per bent valves). The CEL wouldn't illuminate if there was knock... it would simply retard timing. The sensor circuit is where the failure is...

furthermore.. just because you over speed the engine does not mean you'll always bend or float a valve chief.

your logic = fail

 

damm harsh for some one just trying to help and maybe understand a little more about knock sensors and effects

 

I understand what a knock sensor is and how it works. I need assistance on what the ecu's fail logic is..hence the title of the thread... not to be told my engine is knocking and I bent a valve..... because it's not.

 

ok

 

Real simple. The knock sensor is set to "listen" for certain hertz (ie knock), if it "hears" those frequencies, it grounds out and send a signal to the ECU. Nothing real complex about it. Thus, if you have reset your ECU and replaced the knock sensor then there is something within the set hertz range that the knock sensor is picking up that is tripping it. Being that you said you missed a gear I speculated as to what might have happened because it sounds like you've tested all of the electronical aspects of the system which only leaves the mechanical aspect of "you f'd something up" by mis-shifting. Good luck with the trouble shooting though.

http://www.picoauto.com/tutorials/knock-sensor.html

 

I've also checked ignition timing which was spec.. 16 degrees BTDC... with the SCS bridged. Do you happen to know the voltage specs? If it detected knock it still wouldn't store a DTC.

Again.. I'm getting a circuit fault.

 

If it detects knock, it retards timing, throws the CEL on to let you know it detected knock and that its pulling timing and then stores the DTC so that you can pull the code and troubleshoot. That is the way the system is designed to work. However, if you are set on the circuit fault I'll pull out my ELM (the helms electrical book) when I get home and see what it says.

 

That'll work! I highly appreciate it!

 

First three pics are the trouble shooting from main Helms. The last 4 are from the ETM...included all referenced items even though you obviously already know where the knock sensor is. Good luck tracking your problem down.





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Thanks a mil ! I have all that info already tho...lol I know where every bit of the circuit goes..just need to know the ecu logic for failure... for example, what voltage is the ecu looking for at what times on this circuit to determine a circuit failure? What test is the ECU using?

 

bump

 

How do you know you are getting a circuit fault if you've replaced both the knock sensor and the ECU and checked all the wiring? This information would point me in the direction of:
1. engine is knocking.
2. exhaust rattle.

 

The code definition states it as a circuit failure is how I know. If you read the trouble shooting tree, it'll explain the nature of the failure and what they want you to test. There is no mention of checking mechanical condition of the engine or code sets due to a possibility of a mechanical fault. The code sets upon circuit failure... not detection of knock or any other noise. If it detects knock or noise it will pull timing NOT illuminate the CEL.

Thanks for all the help. I chipped another P72 i had laying around... disabled KS and added a few other adjustments.

Problem Solved!

 

You better pray you don't get a knock if you disabled the ks...

 

O lawd... I use premium plus sea foam per fill up.. so i'll be good unless my fuel pump or IAT goes bad..