Knock sensor issue

M

mattwrx

Member
Hey lads first post here outside of the introduction, have the code p0327 on my 03 Impreza WRX conversion, this has more than likely being asked countless times but I'd like to state my own problem that I'm at a loss at
What I've done so far:
• New OEM Subaru sensor
• roughly 60° orientation
• cleaned and tested mounting ground on the block
•Checked continuity from ECU connector B4 (yellow) to knock sensor plug
•Inspected shield wire
•Disconnected negative battery terminal for 1 hour to reset the ECU with new OEM senor

After all this I still have the p0237 low input code as soon as the key is on and it will not clear using my diagnostics. I've read that the MAF can sometimes trigger the code but Im not sure at all, any help is greatly appreciated 👍
 
Update:
Just looked at the live data while it was at idle, checked out knock signal and correction

Signal switches from off to on and back again in a heartbeat so I assume its working as it should

Knock correction stays at 0 while the signal switches at idle, but with a quick rev it states a -5 degrees and back to 0.

So I have signal and correction? Yet the same p0327 low input code remains 🤔
 
There shouldn’t be a knock correction with a blip of the throttle I’d say
 
Move the knock sensor to another bolt point further away and see does it happen again.. it could be picking up noise in engine.. is there an audible sound
 
BazGF8 said:
There shouldn’t be a knock correction with a blip of the throttle I’d say
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I wouldn't know tbh how it should be reading, it's a quick wot to 2.5k rpm that triggers the correction but if I just slowly bring it up nothing happens at all
 
KENC said:
Move the knock sensor to another bolt point further away and see does it happen again.. it could be picking up noise in engine.. is there an audible sound
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I've tried exactly that and it's still instant code when I turn on the key that doesn't clear....🤷
 
Personally...I wouldn't be going wide open throttle below 2.5k rpm to begin with man but not sure if that's causing your problems...
 
Eoinmack said:
Personally...I wouldn't be going wide open throttle below 2.5k rpm to begin with man but not sure if that's causing your problems...
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Yeah it wouldn't be how I drive it normally just wanted to see would something be picked up on the data, I'm gonna take it out for a few test on the road and monitor the live data for anything that sticks out, I'll keep ye posted lads appreciate the ideas
 
Right so after testing it out with the new knock sensor I'm seem to be worse off 😔, seems to be in limp mode now will not rev past 3k and and now have a system too lean bank 1 code and confirms with my afr reading close to 17:1 at idle fully warm... question is would the knock sensor issue cause that?
 
No only detects knock , an engine that running lean will be knocking its head off especially with any sort of load .
So fueling issue, fuel pump , fuel reg, maf , injectors .
I’m going to guess fuel pump or maf , have you much fuel in it ?

Edit , since it’s a conversion , did you run the full wrx engine loom ? Change the fuel pump ?
 
BazGF8 said:
No only detects knock , an engine that running lean will be knocking its head off especially with any sort of load .
So fueling issue, fuel pump , fuel reg, maf , injectors .
I’m going to guess fuel pump or maf , have you much fuel in it ?

Edit , since it’s a conversion , did you run the full wrx engine loom ? Change the fuel pump ?
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Plenty of fuel and have a walbro 255 pump, I've been looking at the MAF readings it's working fine but at idle I'm getting 2.2 g/s which seems a bit low to me, also I noticed how it richens out from 16.7 afr @ idle to 14.7 at 3k rpm which is how it should be at idle
 
How are you checking the afr ? The narrow band sensor wouldn’t be to accurate for anything other than cruise on light throttle and idle
 
BazGF8 said:
I think time to bring it to a professional, my crystal ball has thrown a check engine light
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Maybe not, just figured out the lean problem I decided to want some Choo Choo noises so let off the recirculation pipe thinking what harm, looks like they ain't 100% sealed when closed. Taped off the end to see and ratio is roughly 13.9 - 14.2 on idle fully warm now.....gotta sacrifice psh psh for reliability 😅
 
mattwrx said:
Maybe not, just figured out the lean problem I decided to want some Choo Choo noises so let off the recirculation pipe thinking what harm, looks like they ain't 100% sealed when closed. Taped off the end to see and ratio is roughly 13.9 - 14.2 on idle fully warm now.....gotta sacrifice psh psh for reliability 😅
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So the knock sensor was doing its job and detecting knock????
 
KENC said:
So the knock sensor was doing its job and detecting knock????
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That's still an issue I can't figure this was just another problem I had but wasn't sure if the knock sensor could cause lean conditions aswell as loss of power if Im making sense, key on not running p0327 low input code is there still 😑
 
mattwrx said:
That's still an issue I can't figure this was just another problem I had but wasn't sure if the knock sensor could cause lean conditions aswell as loss of power if Im making sense, key on not running p0327 low input code is there still 😑
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You are looking at this in reverse..
the knock sensor will not cause a lean situation.

The knock sensor when it senses noise will cause the car to run in limp mode and from memory limits the rpm.
So if you have been running lean, which I would of thought is unlikely at idle, if you have any form of Det that the knock sensor picks up it will put the car into limp mode..

What happens with knock sensor in plugged?
 
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