FD3S Code05 Knock sensor
 

Will this code make a bad hesitation stall?
:eek:

you need to be a little bit more specific with your symptoms. It can cause a high rpm fuel cut issue

Clear codes key on engine off. Code comes on Immediately.
Start car-the warmer it gets the worse the hesitation gets.
I need to know if this stall/hesitation is ALL knock related or
a false code being generated from another system.

If the ECU is throwing a knock sensor code, that's from a continuity issue with the sensor not because the car/engine is knocking. Yes, the stock ECU will put the car into a retarded mode with that code being thrown.

Had a similar issue on track a few weeks ago. No CEL light/code, but my goo all melted out of the sensor. The hotter the car got (2nd session), the more the car would fall flat on it's face. Felt like over-boost fuel cut.

You can test the knock sensor circuit by putting a 270,000 ohm (that's also 270k ohms) in place of the sensor and to ground. This will bias the circiut so the ecu won't throw a code; however, you will not have the benifit of the knock retard feature.

I've also had a couple of sensors where the potting goo oozed out. The sensor continued to work fine--I repotted with silicoln sealer and all is well.

I had the most frustrating time dealing with my knock sensor a few years ago. I was experiencing a higher rpm hesitation. I had a boost gauge that was reading a proper 10psi but it sure felt like I was hitting some sort of fuel cut. I changed gauges thinking it might be off a little...no dice. Then I checked over my plugs wires thinking it might be an ignition problem...nothing.

checked codes...found the knock sensor one but had continuity and i think the sensor even ohm'd out correctly.(it's been a while) I was so frustrated that I ran a whole new shielded wire from the ECU to the sensor since my entire harness was pretty crusty at the time and figured why not. That didn't solve the problem and the car was un-driveable because as soon as I hit a steady 10psi in the higher gears it would cut out.

Replacing the sensor finally cured the problem. The ECU will lower the fuel cut values when the knock sensor code is set from what i remember.

replace the sensor if the wire checks out good and save yourself the headache.

Good to know. I got a used one from crispy that still has it's goo and will re-pot my original as a spare to keep in tool box.

I borrowed an oscilloscope and plan to test response of the one with goo vs goo-less. Will try to videotape and upload for reference.

update fd3s Knock code 05
 

Thanks for all the great information. I could start a novel with all the diagnostics done so far.
I like the putting of a 270,000 ohm resistor trick & would like to see a voltage oscilloscope pattern.
Today I found most of the problem as a bad connection SOMEWHERE between the pcm harness & firewall.
I put a jumper wire between the knock sensor connector & engine harness watching the base voltage of 2.6
volts drop to 0 wiggling the harness. Voltage would go up to 4.6V with no knock connected. The kicker came when
I discovered the pcm has no ground to the case untill bolted back up to body, thus no shielding dump from knock & o2 sensors.
I now have an intermittent no code situation, but still heavy hesitation as too lean.
I've decided to scrape the engine harness and use a spare from 3rd car wreck.
More later in chapter 7 land.