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10-17-2019, 09:58 AM | #1 |
Scooby Newbie
Member#: 488200
Join Date: Jul 2018
Location: Brookline, NH
Vehicle:2006 WRX TR World Rally Blue |
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: Current: 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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10-18-2019, 01:08 PM | #2 |
Scooby Specialist
Member#: 469585
Join Date: Jun 2017
Chapter/Region:
W. Canada
Vehicle:2009 STi White |
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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10-18-2019, 02:11 PM | #3 | |
Scooby Newbie
Member#: 488200
Join Date: Jul 2018
Location: Brookline, NH
Vehicle:2006 WRX TR World Rally Blue |
Quote:
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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10-19-2019, 03:42 PM | #4 |
Scooby Guru
Member#: 140444
Join Date: Feb 2007
Chapter/Region:
NWIC
Location: Near Seattle, WA
Vehicle:05 Stage Free LGT ATP 3076, 6MT, AVO FMIC |
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. |
10-21-2019, 09:05 AM | #5 |
Scooby Newbie
Member#: 473969
Join Date: Sep 2017
Location: Pittsburgh, PA
Vehicle:2006 WRX World Rally Blue |
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. |
10-21-2019, 09:19 AM | #6 |
Scooby Newbie
Member#: 488200
Join Date: Jul 2018
Location: Brookline, NH
Vehicle:2006 WRX TR World Rally Blue |
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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10-22-2019, 03:48 PM | #7 |
Scooby Specialist
Member#: 385256
Join Date: Mar 2014
Chapter/Region:
NESIC
Vehicle:'18 Giulia QV '21 Giulia Q4 |
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? |
10-22-2019, 04:03 PM | #8 | |
Scooby Newbie
Member#: 488200
Join Date: Jul 2018
Location: Brookline, NH
Vehicle:2006 WRX TR World Rally Blue |
Quote:
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10-22-2019, 04:14 PM | #9 |
Scooby Specialist
Member#: 385256
Join Date: Mar 2014
Chapter/Region:
NESIC
Vehicle:'18 Giulia QV '21 Giulia Q4 |
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 |
10-22-2019, 05:13 PM | #10 | |
Scooby Newbie
Member#: 488200
Join Date: Jul 2018
Location: Brookline, NH
Vehicle:2006 WRX TR World Rally Blue |
Quote:
Last edited by currancchs; 10-22-2019 at 05:19 PM. Reason: Added clarifying information |
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10-23-2019, 09:29 AM | #11 | |
Scooby Specialist
Member#: 385256
Join Date: Mar 2014
Chapter/Region:
NESIC
Vehicle:'18 Giulia QV '21 Giulia Q4 |
Quote:
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04-29-2020, 12:22 PM | #12 |
Scooby Newbie
Member#: 488200
Join Date: Jul 2018
Location: Brookline, NH
Vehicle:2006 WRX TR World Rally Blue |
Update
Bit of a late update, but there was a bolt (it was the intercooler hold-down bolt, dropped by previous owner) wedged in the driver's side motor mount and rattling around that seems to be the cause of most of my low load knock. Found it randomly inspecting the motor mount for other reasons! Some additional knock was tip-in, MAF scaling, and load-compensation related (high AF corrections in certain ranges while A/F learning was good seemed to cause some issues).
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