P0325 Knock Sensor Circuit 1 Malfunction

[Chris Crash]

Ok, I hate creating threads, but this damn knock sensor issue has been troubling me to no end and I'm out of ideas.

Long story short, after the new engine was put in, CEL was on with knock sensor circuit 1 malfunction. Replaced knock sensor, no change. Replaced connector, no change. Replaced knock sensor again with another one, no change. Replaced ECU with a used ebay one, no change.

Brought it to a family "friends" garage, (not too friendly anymore) and $800 later (replaced connector with new one from toyota, replaced knock sensor with new one from toyota, "replaced" wire with a "new" one, but it didn't look like it) and still has CEL on. That was last summer.

Then when I pulled the engine, I re-did the wiring myself with a new wire, soldered, shielded, covered in tape, shielded with that plastic looming stuff, taped again, more looming, more tape, more tape and more tape.

Still...CEL is on...Hooked it up to an oscilloscope today and the knock sensor checked out fine, so that works.

1) there's no way I'm getting to that wire again, it's too buried in there.
2) What's left to check? I'm out of ideas. My dad and mechanic say get another ECU, but I wanted opinions before I spent money on that.

The ECU, wiring and knock sensor are the only things in this circuit...so what else can I check? I need this fixed so I can pass inspection as I was due last month...

[Mister_Perkins]

Try to connect your defective Sensor wiring to the other bank and see if your problem goes away so you have two Knock sensor running off of one set of wires

[Chris Crash]

What?

5SFE only has 1 knock sensor. Sorry, should have specified this is in the 97 5SFE 5 speed.

[Mister_Perkins]

ooohh . my bad, i thought u had a 4th gen V6. lol

[SilverSoarer]

Possible floating ground. Clean all engine and battery grounds (use sandpaper), use electrical contact spray on contact points, and dielectric grease on connectors - CRC makes good products for this.


See if that changes anything.

[Chris Crash]

Originally Posted by SilverSoarer

Possible floating ground. Clean all engine and battery grounds (use sandpaper), use electrical contact spray on contact points, and dielectric grease on connectors - CRC makes good products for this.


See if that changes anything.

I'll try that tomorrow, but doesn't the knock sensor ground the circuit itself via the block where it threads into?

[Mister_Perkins]

If you cant get the code fixed, go to radio shack and pick up a couple Piezoelectric Sensors (273-073 at radioshack). Run the Positive side to the wire that runs to the computer, and run the negative side to the battery. Then just tape the Sensors to the fuel rail or something that senses good vibrations.

[fenixus]

i'm sure you've seen that before Chris, but here it goes again, maybe it helps the brain storming:

P0325
No knock sensor 1 signal to ECM with engine speed, 1,200
rpm or more
(2 trip detection logic)

Trouble Area:
-Open or short in knock sensor 1 circuit
-Knock sensor 1 (looseness)
-ECM

FSM troubleshooting steps:
1.
a) Remove the glove compartment
b) Disconnect the E8 connector from the ECM.

CHECK:
Measure resistance between terminal KNK of the ECM connector
and body ground.

OK:
Resistance: 1 MW or higher
go to step 3.

2. check the Knock sensor.
NG: Replace knock sensor 1.

3. Check for open and short in harness and connector between ECM and knock
sensor 1
NG: Repair or replace harness or connector.

4. Does malfunction disappear when good knock sensor 1 is installed?
YES: Replace knock sensor 1.
NO: Check and replace ECM

[csaxon]

Did you put anything on the sensor threads that could interfere with grounding?

[Chris Crash]

This might be a dumb question but I'm new to electrical problems, how do I check for open or short in the wire?

also, where'd you get such detailed instructions/descriptions of the CEL? I've never seen that in the FSM.

csaxon, I don't think there is anything on the threads (like teflon tape or sealant) but the most recent knock sensor in there was installed by the mechanic when he was trouble shooting it, so maybe there is. I'll pull it off and check when I get home this afternoon as I'm in Greensboro right now.

[Mister_Perkins]

If you have a short in your wiring harness between the sensor and the computer when you were checking the wave forms with your Scope the forms would have been distorted. To check for a short, disconnect both sides of the harness so both plugs are not connected to anything. hook up a multimeter and measure Continuity the total length of the wire. If its broken, it will not have continuity. If its solid it will have continuity (Infinite)

Also check the resistance. It should have some form of resistance. IIRC I think 16 gauge wiring should have somewhere around .047ohms of resistance per foot. I could be wrong on that though.

[Chris Crash]

With the o scope I checked the knock sensor only, not the wiring.

I'll check for continuity in the wire later today, it's supposed to hit 75 degrees today, so pumped!

[fenixus]

Originally Posted by Chris Crash

also, where'd you get such detailed instructions/descriptions of the CEL? I've never seen that in the FSM.

PM sent

[Mister_Perkins]

Originally Posted by Chris Crash

With the o scope I checked the knock sensor only, not the wiring.

I'll check for continuity in the wire later today, it's supposed to hit 75 degrees today, so pumped!

Oh .. to make it easier, I would just scope the Sensor wiring then. You could tell right off the bat if its bad. If the wiring is shorted, or not grounded properly, your Wave forms will not be uniform on the wiring.

One other thing you could do is disconnect both connectors and probe the wiring harness and check for continuity between the harness and the body. If the wire got rubbed and is touching the body, that could mess it up too. The sensor is very basic though so theres really not too much crap that could go wrong

[Chris Crash]

I don't have the o scope anymore, and it was very complicated to use haha. Took forever to just get a damn wave.