2005 LGT False/Phantom Knock Issues

[Shoeiz22]

Hello all this is my first post within this forum so hopefully I do this correctly. I am currently having this issue where between 2000 and 3000 rpm I will see around -12 sometimes less of feedback knock on my accessport V3. Within this range also, my AF correction is all over the place like -+25 or so. Outside of this rpm range, the car runs fine 0 knock or anything. I have taken it to a shop and had the coils and plugs done with OEM subaru coils and NGK plugs.

 

The shop believes it might be some noise coming from the drivers side valve train causing this issue but my question is why when it is cold does the noise not exhibit itself but when its warm it does make this ticking noise? I realize subarus make some noise which is confusing me as to why the car thinks its knock.

 

Another theory I have is that an injector is going bad and causing this AF correction non sense and "knock". The car passed the compression test and there is no rod bearing material in the pan or the oil. Does anyone have any idea what this could be? Thank you for the help!

datalog5.csv

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datalog1.csv

Edited April 30, 2021 by Shoeiz22

[bubbagump]

I had a similar issue years back and after some forum digging concluded the first thing I should do is replace the knock sensor. It is easy to get to and not very expensive. In my case it cleared the issue right up. For what it's worth, my valve train is pretty darn "clicky" too. Planning on having clearances measured/adjusted if needed soon.

[xt2005bonbon]

How do your long term fuel trims look like?

 

 

 

Have you been able to really narrow it down to exactly which conditions it knocks? What is the approximate load range (in g/rev) for example? If the Af correction is moving around, this means that you are still in a closed loop situation then. Basically, you should log to figure out under which conditions you are knocking. In my opinion, if knock is real, then it is either running too lean or there is just too much timing in that load/rpm area of the timing table.

 

 

I am currently suffering from some knock at fairly low load (~0.85 g/rev) in that rpm range you are mentioning. Although in my case, it is in open loop (no fuel correction). I know I am meeting the target AFR. So, I have been reducing timing in that area where it keeps knocking. But it is still showing knock. Although, when it pulls it, I do not feel a loss of power. So maybe I am passed MBT and need to keep pulling timing. Or, it is plain false knock and just noise. The ECU rarely 'learns' it anyway. So I am guessing the amplitude of the knock signal may be fairly weak.

[Shoeiz22]

Thanks for all the replies everyone, my valve train is also quite ticky, I will also see if replacing the knock sensor fixes any of those issues. I know sometimes the hood scoops cause water to get in there and corrode the connector. Thank you!

[Shoeiz22]

xt2005, my long term fuel trims seem to be fine but I do get a lot of AF correction in this range, I am thinking maybe it is a fuel injector related maybe it is dying and causing just the right frequency to make it go off? Who knows. I made another post with the logs if you want to look at them there. It is mostly between 2000 and 2600 rpm with about 30-40% throttle in 3rd and 4th gear cruising or taking off.

[Shoeiz22]

How do your long term fuel trims look like?

 

 

 

Have you been able to really narrow it down to exactly which conditions it knocks? What is the approximate load range (in g/rev) for example? If the Af correction is moving around, this means that you are still in a closed loop situation then. Basically, you should log to figure out under which conditions you are knocking. In my opinion, if knock is real, then it is either running too lean or there is just too much timing in that load/rpm area of the timing table.

 

 

I am currently suffering from some knock at fairly low load (~0.85 g/rev) in that rpm range you are mentioning. Although in my case, it is in open loop (no fuel correction). I know I am meeting the target AFR. So, I have been reducing timing in that area where it keeps knocking. But it is still showing knock. Although, when it pulls it, I do not feel a loss of power. So maybe I am passed MBT and need to keep pulling timing. Or, it is plain false knock and just noise. The ECU rarely 'learns' it anyway. So I am guessing the amplitude of the knock signal may be fairly weak.

 

I have narrowed it down to that scenario in my post below but I have attached some logs to help make it a bit more clear on where it is occurring.

[xt2005bonbon]

I'll have a look.

Does the car jerk a bit between 2-3k? There is a thread on the forum documenting the stutter many of us have been getting in that rpm range at part throttle.

If it does not feel jerky, can you feel a loss of torque when timing is being pulled?

 

 

Also, make sure you have checked all around the engine bay for anything loose (e.g. exhaust shield, engine cover, etc..)

[Shoeiz22]

Yeah the car feels quite jerky between 2000 and 3000. The stutter is due to timing being pulled in that range because the car thinks its knocking. I have checked all around for anything loose, my shop thinks its my extra "ticky" valvetrain causing the knock to be picked up but I think its something else causing that. Im at a complete loss though.