Alright so I have a 92 si, stock h23a, stock ecu. It has been throwing the knock code for awhile and I finally got around to replacing the sensor. I reset the ecu and all that and it will still throw code 23, the weird thing is its very sporadic. Sometimes it wont even throw the code, doesnt matter how you drive it. Im very lost on what to do but I hate the limp mode it goes into when throwing the knock code, any ideas on what to check?

 

Wiring from the ecu to the knock sensor.

 

What are you saying?

 

There is probably an issue in the wiring from the knock sensor to the ecu. Maybe it is rubbing on something, maybe it has a loose connection. In any case it is causing the ecu to see what it thinks is a knock signal.

You need to verify that the sensor is good, and check the wiring in the engine harness, and harness to the ecu, including moving it around as it can move when the car moves, and see where the issue is. If you have any extra wiring added in, like a piggyback harness or such, that would be the first thing to check.

I had a phantom issue with my map sensor for ages, finally tracked it down to a loose connection in my Boomslang harness for an Apexi neo. took it out and the problem was solved.

 

Ok ill check that. I have a suspicion though so im going to give you all the long sad story. So I had three fault codes 4 weeks ago. Knock, egr, and eld. I replaced the egr and the knock and reset the ecu like youre supposed to. Funny thing is my eld code went away but egr and knock are still going off? I was digging around in my fuse box and the ecu fuse looked like it was cooked (wiring was black and warped), it had no resistance value but my ecu was still working? So i reppaced that fuse reset the ecu and i still have tge same faults. Anyway, is there a chance my ecu got cooked or am I dealing with a very rare coincidence where my egr and knock wire are both shorting out?

 

Anything is possible with an electrical issue, if you have already replaced the knock sensor and egr valve and checked the connection from ecu to the bulk head connecter in the engine bay and from the bulk head connector to the ks and egr valve, the book says to substitute a known good ecu and if no cel is detected then replace the ecu

 

Could also be an issue with the fuse box, sounds like something got hot for some reason, so a wiring issue in the fuse box, or somewhere else. Could take a bit of work to find it, testing individual circuits for draw and resistance etc.