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Low load knock - Pre Infamous1 tune


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Hi all,


I am going to be getting my car (2005 LGT 5MT wagon, ~80k miles) tuned, but I want to confirm that the knock that can be seen in the logs is a tune issue, not a mechanical issue.


First, I'd like to give a brief description of the problem: car will stutter/jerk/pull timing (somewhere in 1500-2500 rpm typically). It did this when I was stage 1 and stage 2 OTS. I belive my stock TMIC had some separation on the ends and was causing a lean issue, so that was swapped out this week with an IPR TMIC. I don't think that this was actually the case, in retrospect. I planned on getting a tune after the intercooler install.


I drove it around to check for leaks and verify my install. I did not notice any knock events on the accessport (by now it had been a few weeks since the last reflash - I assume it had stored the knock correction, thus my looking at knock detection did not yield much).


It drove around fine for my 12 mile round trip commute in the 1500-2100 rpm range - typically 5th gear.


Fast forward a day and a half... car is acting like originally described. It will go from DAM of 1.0 to 0.33, then it will go back up to DAM 1.0, probably back to 0.33, and then eventually I suspect it will go to 0.1 as it has in the past.


Any help or comments are greatly appreciated. Thanks!


P.S. I primarily made this thread to help out Infamous1.



Current Map:

-Cobb OTS 1.18 Stage 2 91 LC


Current parts:

-Stock air intake


-Invidia up pipe

-CNT catted downpipe

-Stock CBE


To Do (tomorrow):

-put in new stock heat plugs (I don't know how old the originals are)

NEW PLUGS IN: similar results, but only after I drove it around for a while: post permalink


Log descriptions (taken this morning; pre-spark plug install by two days)


***these logs are with -5° timing applied globally by APv2***

log starting from the moment I turned the car on in the garage and reversed out, then drove until car warmed up. (merge 41_1 and 41_2


1-2 pull and some cruise afterward

cruising 55-65ish mph, some throttle modulation


*I do not have a laptop or vag-com so I cannot run learning view.





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Have you taken a close look at the inlet tube (runs under the intake manifold and connects to the turbo)? Common spot for leaks. I had mine replaced a few months ago because the rubber was completely corroded.


Where are you located?


Edit- And you've been putting premium fuel in, right? (Sorry- Just had to ask).

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Thanks for the reply. I had taken my entire intake apart and examined it for leaks (thank goodness I had some ingenuity and figured out I had to twist it on or else I wouldn't have been able to put the inlet tube back on XD). Everything looked fine. I am contemplating changing the inlet tube and intake, but is there really a noticeable performance advantage?


I checked the vacuum lines for good seating and they seemed to be fine.


Now on to gas... I have been using the same 2 Shell stations nearest to me in southern Maryland. Both yield same result. I am contemplating taking a sample of fuel for one of my coworkers to examine - maybe they've been skimping the tanks???


However, I find this unlikely as I have also filled up in Delaware and Virginia with similar results. Again, all using Shell 93 octane.


I am heading into the garage to change the plugs, especially since it's warm at 38°F outside.


Also, no offense taken for the premium fuel. Some people just don't understand the reasoning :spin:




EDIT [2012.06.28] I replaced my inlet tube, which did have a small tear in the thread area. It is still questionable if this was the culprit, but my IAM has been staying more consistent and I rarely go into limp mode.


I have also replaced the intake manifold o-rings, and placed my stock throttle body hose in place of the AVO unit with my IPR TMIC.


I should do a compression and leakdown test to verify engine health since I have put approximately 23k on it since the start of this thread.


Also, one of my spark plugs had developed a crack (the ones I originally replaced later on in this thread I had dropped). This was a cause of a phantom misfire and eventually threw a CEL.


I have also added: fx-300 and oem wrx smfw. The OEM dmfw springs were broken internally and causing an abnormal vibration at 1500 rpm.

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Reset the ECU, put the timing back to normal with your AP. Drive around *normally* until DAM goes back to 1 (it starts out at 0.75 when you reset the ECU and your car has to warm up first) and then make new logs.


Do some logs in 3rd gear WOT from 2k-6K. Someone else jump in here if I'm wrong, but I think that'd be a lot more telling. Also, do some logs of the other stuff you want as well.

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I guess it could be the plugs...but when I was running a Cobb Stg2 91 octane map with just an STi uppipe and gutted shorty, my IAM never really got below .875. So I don't think it's the map. Something is making your car more knock-prone.


Are you able to use your AP cable to get a learning view screenshot?

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Yeah I have the new cable anyway, it has a 10-pin connector to the AP. I won't have a laptop for a couple of months - I will order a vag-com this week and maybe I can borrow a laptop from a friend.


I should reiterate that my DAM will go to 1, then down to 0.3 then back to 1. It presently is at 0 :mad::spin:


iNVAR, I'll try to get some logs tomorrow. I did a quick run around the street here and it was recording knock at -12° correction and then -12° detection ~20mph 3rd or 4th gear / 1500-2100 rpm.


WOT seems to have no issue with knock.


Hopefully Infamous will chime in. New plugs in tomorrow.

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Watch it be something dumb...like a burnt valve :(


I'm in the garage changing the plugs now. I'm going to pull off my freshly installed IPR intercooler and check the seating of the knock sensor, as I read someone on the forum said theirs was loose.


I'll double check my entire intake for leaks again.


I have the driver's side front plug out and it is the original plug I think (NGK SILFR6A). I'm hoping I find something really wrong with one of the plugs (plugs and coil packs are my car jinx - my car issues typically revolve around them :lol:).


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Yeah so they are all out. Taking a couple mins of break for my back and then going back to put them all in.


Above photo is an example of all four. Similar browning on the porcelain. I saw some silvery material on two of them on the cylinder face (the circle part that sits inside cylinder head) and my heart sunk for a second... until I realized that it was just anti-seize :).


Do the plugs look indicative of anything?

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You're putting the same plugs back in? With 80K miles on them?? Why would you do that?!? Replace them!!


edit: Oh wait, you *are* putting in new ones. Phew. The plug looks okay to me... but I'm hardly an expert or even an amateur when it comes to reading plugs. Besides, your picture is blurry. :p

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Noooo I have replacements on my kitchen table!!! LOL


Yeah I'll upload a new pic after I get the plugs in. I hate my back. It make engine work a real pain (pun intended) :(


6:40PM: Plugs in. Coil packs 2/4. Other two are happier off than on :p


7:40: done, but I found a bolt that I dropped in a previous install and managed to dislodge it further into the engine... Good 20 minutes of attempting to get it out lol. Soon to attempt again.

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After changing the plugs, I took it for a drive around and had zero knock. I got the DAM to 1.0 and everything was good. I was almost home when I went over a rather deep bump in the road and then proceeded to notice more knock. I think it was coincidental.


3rd gear pull was uneventful, DAM was still 0.7 at that time though (became 1.0 shortly thereafter).


Posting logs in a few minutes.


e: upon review of the logs I found some knock in the first log, but most minimal, however. the last log shows the -12° crap again.


Needless to say, this is pretty frustrating. I really want to think it's the Cobb OTS tune plus the gas acting up.





Logs posted to google docs for your convenience:


datalog46.csv: reversing out of the garage, then driving around the local streets for a few minutes. Notice minimal knock

datalog47.csv: row 1237 starts 3rd gear pull

datalog48.csv: after DAM to 1.0, and the return of the terribly annoying -12° knock detection

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At this point I'm almost positive it's the tune (right now I have a realtime map flashed on a basemap of same name). When DAM gets to 0.9 and the knock correction is minimal (like -1.5°) zero knock.


Will post logs later.


At this point I'm willing to bite the bullet and get the infamous tune. Anyone second that?

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My car knocked quite a lot of the cobb OTS tune. I even put 93 in it and ran the 91 tune and it was still pulling timing. A proper pro-tune solved all the problems. I wouldn't ever run a cobb OTS map again, my logs looked like hell, almost like mechanical problems were going on.
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Yeah SCGT, I think you are right. Winter gas + COBB tune officially sucks.


I am now debating on going to IAG for a protune/give car a good once over for sanity or getting Infamous to etune me.


Latest log from tonight: reset ecu when car was fully warmed and been driving, continued to drive gingerly at only partial throttle and no quick acceleration. I had about 1/2 tank fuel - maybe I had some bad gas mixing in there? I don't know where the fuel pump pulls from or the density and mixing variations between gas.


datalog59.csv on google docs

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