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Old 10-17-2019, 10:58 AM   #1
currancchs
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Join Date: Jul 2018
Location: Brookline, NH
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2006 WRX TR
World Rally Blue

Default Need advice on Timing

Purchased the car as a project a while back and have finally sorted the mechanical issues, now looking into the tune (done by previous owner). Would appreciate any input or tips on the best way to go about this.

Some background - The vehicle is a 2006 WRX TR with a Walbro 255 fuel pump, one step colder plugs, an AEM cold air intake (in fenderwell), and a TD05-20G (saving up for a new intercooler, I am pretty sure the stocker is inadequate for my current turbo, especially once I turn things up a bit). I do have larger injectors (750cc) on hand, but am currently running low boost (~16psi peak around 3500RPM, very slight taper to redline) on stock injectors (565cc) until I have a chance to better scale the MAF.

Of most interest to me currently is the timing. I have plugged stock and current values into Airboy's spreadsheet (thanks for sharing!) and got the following:

Stock:
https://i.imgur.com/Syoe6fj.png

Current:
https://i.imgur.com/PTW0AuJ.png

The engine is not knocking under any significant load, but I do see some knock at very low loads/steady state cruising (e.g. around 2k RPM, 40mph, barely on the throttle) (using a G4 Knock Light, nothing on the logger), even though timing is lower in this region compared to the stock map (although my AVCS map is different in this region - the high factory values have been replaced with values close to those in surrounding cells).

I had originally considered lowering timing a few degrees in this region, but wasn't sure that I should being that it is already lower than stock (didn't want to raise EGTs and don't have an EGT gauge, yet, for monitoring - I do have an AFR gauge, a boost gauge, and an oil temp/pressure gauge).

Also, looks to me like timing should be raised quite a bit at high RPM/high load, a bit at high load/mid-RPM, and smoothed quite a bit.

Would appreciate any feedback on the map/my thoughts on it. Thanks for reading!
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Old 10-18-2019, 02:08 PM   #2
JSR84
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I wouldn't worry about it too much as long as its not above -2.8. the knock sensor is notoriously inaccurate at low RPM/load. If you want, try removing some timing in those areas and see if it goes away.
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Old 10-18-2019, 03:11 PM   #3
currancchs
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World Rally Blue

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Quote:
Originally Posted by JSR84 View Post
I wouldn't worry about it too much as long as its not above -2.8. the knock sensor is notoriously inaccurate at low RPM/load. If you want, try removing some timing in those areas and see if it goes away.
Thanks for taking the time to respond. Interesting thing is that I am only seeing knock on my G4 knock light, no timing is being pulled by the ECU and nothing audible. I also found it interesting that the stock timing values in this region are somewhat higher than my current timing, which is why I was hesitant to lower it any further (don't want to melt something and don't know what my EGTs are since I don't have a probe/gauge at the moment).

Anyways, just ordered an EGT gauge so that I will know if I am running timing that is too retarded while tuning; that should take the guesswork out of adjusting timing and give me some peace of mind that my changes are for the better. I'll post an update once I resolve this, but that may not be for a bit, as I haven't had as much time to to wrench on the vehicle as I would like lately...
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Old 10-19-2019, 04:42 PM   #4
NSFW
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05 Stage Free LGT
ATP 3076, 6MT, AVO FMIC

Default

I agree with no worrying about "knock" at low load, it's probably noise. At low load, the actual knock threshold is higher than best-torque.

Another way to look at it: if the dynamic-advance timing table has zero in that area, that's because Subaru's tuners decided that it's safe to run full advance there even with crap fuel.

I tried reducing timing around 2000 RPM at low load to see if it made any difference, and the "knock" signals never stopped. However after I pulled enough timing, the car ran like crap in that area, with lots of lurching and surging.

That said, I found that l limiting advance to 38 degrees above 3500 RPM or so got rid of some "knock" signals that I had in that area when shifting gears. I still wonder whether it was really knock or just noise, but the fact that it went away with less timing makes me think it might not be completely false. And I don't spend much time driving in that area anyway.
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Old 10-21-2019, 10:05 AM   #5
StarkWRX
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As everyone said, you will usually see knock either shifting or cruising. I typically cruise about 2500-3000 rpm in 5th and I see -4 to -7 sporadically. The engine has 170k miles and still runs great (besides a head gasket issue).

The FSM says 17*/700 rpm of advance. That should be a good guide to compare your tables with.

Also consider that your car (and mine) are 13 years old and might benefit from a fresh knock sensor. I’m not sure how long they’re supposed to last but I’m changing mine very soon when I install my new engine.
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Old 10-21-2019, 10:19 AM   #6
currancchs
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World Rally Blue

Default Thanks for responding!

StarkWRX and NSFW - Thank you for sharing your experiences and thoughts, I appreciate you both taking the time to do so! This information will definitely be helpful when I start making adjustments after seeing what EGTs look like.
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Old 10-22-2019, 04:48 PM   #7
86Dreams
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'19 Giulia Q4

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could be knock prevention or it could be that they were trying to spool the turbo faster by generating more egt from the lower timing.
how different are the fuel maps?
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Old 10-22-2019, 05:03 PM   #8
currancchs
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Quote:
Originally Posted by 86Dreams View Post
could be knock prevention or it could be that they were trying to spool the turbo faster by generating more egt from the lower timing.
how different are the fuel maps?
Thanks for taking a look! Fuel maps are pretty similar. No difference at low RPM/low load, a bit more fuel in the midrange, and less fuel up top (10.75 AFR targeted at max load/RPM). I've included screenshots of my modified fuel map, a stock fuel map, and a stock map showing stock values compared to my modified map, below, for reference.

https://i.imgur.com/GlNvTS9.png
https://i.imgur.com/a7tcQiL.png
https://i.imgur.com/ZSPMYF7.png
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Old 10-22-2019, 05:14 PM   #9
86Dreams
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V7 S204
'19 Giulia Q4

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the differences are realy not that drastic.

Timing wise that crease around 1.7g/s is probably because of the leaner afr. You could try grading that transition. The wide open throttle timing in the modified map is actually slightly higher, the stock load axis stops at 2.5 g/s, at 6k rpm is about 17.5*, in the modified map its a little higher and raises to about 19* past 6k for 2.5 g/s
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Old 10-22-2019, 06:13 PM   #10
currancchs
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2006 WRX TR
World Rally Blue

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Quote:
Originally Posted by 86Dreams View Post
the differences are realy not that drastic.

Timing wise that crease around 1.7g/s is probably because of the leaner afr. You could try grading that transition. The wide open throttle timing in the modified map is actually slightly higher, the stock load axis stops at 2.5 g/s, at 6k rpm is about 17.5*, in the modified map its a little higher and raises to about 19* past 6k for 2.5 g/s
Thanks for the tips! Also, just to clarify, I see no knock at high RPM/Load using this map, just the (possibly phantom) low RPM/load "knock" (wasn't sure if your mentioning that I'm running higher timing past 6k RPM for 2.5 g/rev was in response to my mentioning, in an earlier post, that timing on my modified map was lower than stock - this was intended to refer to timing in the low load/RPM regions of the map).

Last edited by currancchs; 10-22-2019 at 06:19 PM. Reason: Added clarifying information
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Old 10-23-2019, 10:29 AM   #11
86Dreams
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'19 Giulia Q4

Default

Quote:
Originally Posted by currancchs View Post
Thanks for the tips! Also, just to clarify, I see no knock at high RPM/Load using this map, just the (possibly phantom) low RPM/load "knock" (wasn't sure if your mentioning that I'm running higher timing past 6k RPM for 2.5 g/rev was in response to my mentioning, in an earlier post, that timing on my modified map was lower than stock - this was intended to refer to timing in the low load/RPM regions of the map).
Ah, I thought you meant the high portions. As has already been said, knock happens at low load and its sort of just a statistical probability that you cant 100% avoid. Cruising Knock and noise show up under fine knock learning. Feedback knock correction can pick up knock but will also observe knock related to transient conditions such as incorrect tip in enrichment, or may even pull timing when load rises rapidly(even when no actual knock is observed). Some others may be able to comment on that last bit more.
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