06 lgt stage 2 knock questions

Hello everyone,

 

I have been trying to get rid of some feedback knock and fine knock learn that is showing up on my stage 2 OTS setup. I found some boost leaks and am fixing those now. I also replaced the spark plugs with the ngk silfra6 plugs.

 

Setup:

06 lgt sedan manual 88k miles

New turbo vf40( previous owner blew it up, never changed banjo bolt)

Filter removed from banjo bolt now

Cobb catted downpipe

Invidia catless uppipe

Invidia q300 catback exhaust

I used grimmspeed gaskets for all exhaust work

Grimmspeed turbo heat shield

Stock airbox and filter

Cobb v3 accessport running 93 octane stage 2 OTS tune

 

What would be the areas to troubleshoot knock next after I fix all boost leaks and have new plugs and clean the MAF sensor and I still see issues?

I also have some techron fuel injector cleaner I was planning on running through next fillup.

 

I am seeing -12 max feedback knock

-4.2 max fine knock learn

The DAM has not gone below 1

 

I definetely have knock when shifting but also during WOT in 2nd i see feedback knock around -6 to -12 and fine knock learn of -1.05 to -4.2. Since this run I havent done any driving in boost.

Edited March 2, 2017 by WaRpEd

My current next step after boost leaks fixed and fuel injector cleaner is to try the 91 octane OTS tune.

If I am still seeing issues should i look at the fuel filter?

 

Ill grab the datalog of ones i have saved when i get home tonight since that will help more than me explaining.

Edited March 2, 2017 by WaRpEd

-12 and -4 are pretty significant knock events. You need logs.

Ill post logs tomorrow, thanks

Check (and listen) for possible sources of mechanical rattles, like from a heat shield, or a suspension component. We had some similar knock (DAM reduced as well) on the Saabaru due to loose-fitting caliper pins, the tap-tap/rattle had the knock sensor picking up big events. New o-ring around the pin and no more false knock.

I'll look around for any rattles. However would this show up when I'm not doing pulls? The pull I did yesterday I had -4 feedback knock during WOT 3rd gear pull. and when cruising had random fine knock learn around -1.2. I'm out of town and don't have the file but I'll post the log of the pull and cruising when I get back tomorrow.

 

Thanks for the help in advance everyone.

Alright I attached a 3rd gear pull as well as a cruising log.

First time posting logs so if I am doing something incorrect or missing values please let me know.

 

Currently to my knowledge the boost leaks are fixed however I don't have a boost leak tester. I replaced the throttle body hose with a mishimoto and I replaced the turbo/intercooler O-ring/gasket with OEM.

3-3-17 3rd gear pull.csv

3-3-17 cruising.csv

As far as mechanical rattle I do have a heatshield missing one bolt that I'll get tightened up however its not really "rattling". There are a few random bolts missing on random items that I'll try and tighten up. But from my limited knowledge so far the logs to me look like actual knock... but since I purchased the car after the turbo went on the previous owner I want to check hardware for issues too.(when I purchased the car it was completely stock, in retrospect should have added the accessport and figured out issues before stage 2 but...learn for next time)

So looking at this again i missed that i am overboosting to 18.22 psi when the tune should be 16.5 psi. What are the causes of overboost that I should look at?

There's nothing concerning to me as far as knock goes in the cruising log. You only have 1 feedback knock event, and it's not even when you're on the throttle, so don't worry about that one. I get those from time to time.

 

The other event in fine learning is also very low load, nothing I'd be concerned about.

 

Your WOT log, on the other hand, is concerning as you are in heavy boost, and actually overboost. To answer your question about what causes it, it happens because:

 

1) It's an OTS map, so it's one size fits all. Every car is different and as such will respond to a map differently.

2) It's also very cold. In cold weather (your intake temp only reads 34 here) boost come up very quickly. As such, your car is overshooting the 16.5 target and there is too much timing advance for the higher boost you are seeing.

 

Solution? Get a custom tune. That's really the only way to fix it because I don't see a LWG (Low Wastegate) map available on COBB's site anymore.

 

A custom tune can fix your knock in a few different or combined ways depending on the tuner:

1) Adjust the compensation table for WGDC to be lower overall.

2) Pull timing where you are seeing knock.

3) Adjust Turbo Dynamics to prevent overshoot.

4) Add fuel where you are seeing knock.

5) Make the boost target curve smoother to prevent overshoot.

6) Adjust WGDC tables.

Well thats good to hear a tune can sort things out. Really appreciate the feedback! I am probably going to get a boost leak tester rigged up to be sure thats not an issue and remove any rattles them ill get a custom tune.

Thanks, this car will mostly be a summer car (couldmt wait till summer to start upgrading...) should I wait and get a tune when its warmer, or will the ecu adjust accordingly?

One other question, I tried the 91 octane map yesterday and between shifts I am seeing feedback knock correction of -4 max what causes the knock between shifts is it just pulling too much fuel when I put the clutch in and getting lean?

Are you shifting very quickly?

 

Also, a good custom tune will get you improved performance too, so that's in addition to the safety factor with the knock. You can do the tune in whatever weather you want, and the are compensation tables built in, but may require a little tweak when the weather changes.

 

I did my own car in the spring, so when summer came I had to tweak the hot side of my compensation table to hit the targets. Then when winter came, I tweaked the cold side to stop over post.

 

Some tuners don't even tweak the hot side though, so you end up not hitting your boost target in much hotter weather. It's safe that way though and you really don't eek out that much added performance from our tiny turbo and an extra pound of boost in the higher RPM range in 120 degree weather.

okay, ya I would rather be on the safe side of a tune, not trying to beat any records, just want a fun car for driving around.

 

Okay I rigged up a very basic boost leak tester and I found out my intercooler has a small leak between the plastic end and the intercooler on the turbo side.

 

Whats the best way to fix this? Or would I be better off with an aftermarket(which would be best?) and then get the car tuned?

http://legacygt.com/forums/showthread.php/bulletproof-tmic-mod-lgt-08-wrx-158870.html

Hey everyone,

 

update:

 

Installed new knock sensor

Installed Grimmspeed TMIC

Did boost leak test and all good.

Checked exhaust connections and heatshields, all good.

Currently have tank of gas with techron fuel cleaner in.

 

 

First cruise around this is the log, skip down I am seeing -11.95 feedback knock not sure whats going on. I need some confirmation this can be tuned out and I don't need to do any other component related things first. I don't want to pay for an E-tune to find out theres other issues.

 

Also I don't have a wideband O2, has anyone gotten an e-tune without one?

datalog10.csv

Start with the basics of proper logging. TA put together a nice .pdf which I've attached. Do an Idle, Cruise, and WOT log as per their instructions.

 

With DAM at .75, and feedback as high as -12, I'd be looking for a mechanical issue, but I'd also get in touch with a good tuner to help you pinpoint it. Speak to them before logging more, as a few WOT runs with big knock can definitely do some damage...

Subaru Logging Guide.pdf

Most of the big FBKC seen in the log is at light throttle/cruise or during light/moderate throttle shifting. There is one instance where a large correction is made just after letting off the throttle at ~4k rpm from ~30% throttle, with what appears to be no shift involved (or more likely a very very slow shift), time = 552.9 sec, datalog row 6286+. Would seem to be caused by an external/mechanical source. I had very similar logs a few years ago caused by my IPR TMIC buzzing against the pitch stop mount during shifts. There was so little clearance b/n the bottom of the TMIC and the pitch stop mount that it didn't take much rocking of the engine to cause the TMIC to make contact w/ the pitch stop mount.

Thanks for the input. Ill check everything over and see if somethingis rattling again. I also ordered a new pcv and inlet and will install those soon. I think after that Ill try to do the correct logs and then look at getting a tune. I don't have a wideband O2 any opinions on getting an etune without one?

Thanks for the input. Ill check everything over and see if somethingis rattling again. I also ordered a new pcv and inlet and will install those soon. I think after that Ill try to do the correct logs and then look at getting a tune. I don't have a wideband O2 any opinions on getting an etune without one?

 

You can definitely get an etune without one to try and fix your cruise/idle problems. But anything more than that (open-loop fueling, running at higher loads/WOT, etc.) and the tuner will just be guessing without a wideband. Granted, I trust that it's not that hard to guess well, but it's hard to definitively tune for safety and performance simultaneously without a WBO2.

Truth, not necessary but definitely beneficial. Add an EGT for even more info/fine tuning. In a perfect world we'd have sensors on every cylinder, intake and exhaust.

Thanks I'll look into a WBO2 when I get other issues sorted out.

 

I think I am doing the boost leak test wrong as I can't build pressure.

I have the turbo inlet connection to the pcv plugged and the oil fill unscrewed.

Do I need to plug anything else? The pcv side I have the crankcase open to atmosphere and then the line going to the throttle body open to atmosphere. Do I need to plug that end?

 

I am just using a bike pump to fill so it's hard to tell if/where I am leaking since I can't build any pressure.

Figured out what I was doing wrong for the boost leak test. Got that sorted and no leaks there. Did an idle log and a cruise log. I however was seeing feedback knock still up to -10 just driving in town not in boost, unfortunately didn't log that but it was between shift or in 3rd gear that I have noticed this spike in feedback knock.

I realized my clutch is squeeking while pressing down and there are two plugs that I need to zip tie or something since they can move and rattle. I'll take a look at those this weekend and see if those are causing the external mechanical noise.

idle and cruise logs

Idle Log.csv

Cruise Log.csv

Do you have an atmospheric BOV? The spikes during shifting can be due to that.