MS3/ATR: partial throttle knock

[Fobio]

A few of us have reported phantom knock @ cruising speeds in the higher gears....theories abound as to what causes it and how to solve it. From 2nd hand info, I heard that Christian @ Cobb can possibly "tune" this knock away, albeit at the expense of fuel economy. I may expand on that theory with more posts, here's a development and findings that can help you tune away the knock yourself:

http://www.mazdaspeedforums.org/forum/pt-performance/26996-why-does-your-motor-blow-10.html#post224792


FYI, like everyone i had knock (about 2.5cts) on light throttle after startup. Also had the 6th gear cruzing part throttle knock. Well NO knock anymore . I simply retarded timing at low loads between 2500 and 5000 rpm in the first 3 load columns in the part throttle knock maps. IMO factory maps are WAY too advanced and the ecu wants to hit almost 60 deg + under light load. Based on my experience with other cars i reduced timing in those areas to 45 - 47 deg and NO KNOCK. I have logged about 200 miles since that last change. My DH is set to flash at anything over 1.0. FYI mileage might have dropped but i willl only know when i do a full tank run on my next long drive.

Harry

[mleblond]

Nice find, at this point I don't really care about fuel economy when the engine knocks at low rpm's

[Fobio]

here's a pic of ztuner's table:

http://ztuner.com/atr.htm

http://ztuner.com/images/atr/timing.JPG


No disrespect to ptp but i think a simple catch can should solve the oiling issue if indeed it is as bad as he suggests. its not rocket science. Deleting EGR simplifys things. i do it on all my Z builds simply because it makes service easier and i am not as gas mileage concious on a 600 - 700 whp Z. Emissions can be passed anyway with tuning adjustments except the roadside CA scans. (****ing CA). I think pulling back timing is a big step and very easy. Here is a link to my timing map. Only the low load settings have been changed. Pull up your stock map and the differences will pop up immediatly.

Untitled Document (http://ztuner.com/atr.htm)

Harry

[Fobio]

from what I can tell, the values ztuner is using in the the top 3 - 4 rows pulls quite a bit of timing. you may feel the car is "sluggish". this to me is just proof that the phantom knock can be tuned out at the expense of emmission, spool time and fuel economy. keep an eye out on the difference between these values vs. stock values. you may want to adjust them from these settings to get the ideal tip-in/pick-up you desire.

[Fobio]

well...with the warming weather, and guys getting more enthusiastic and motivated to drive their cars, there's lotsa talk again of popped motors on MSF. Mainly, a StandBack tuned car blew on EECMM @ Tail of the Dragon...4300' elevation, up and down twisty mountain passes, lots of part-throttle driving...car went boom in the middle of a cruise/rally.

this caused a lot of concerns for guys...and what came out from the discussion is that tuning Part(ial) Throttle is paramount as most cars that went boom so far lost it @ PT, not WOT.

So, having gathered some info on what the car does in those situations and what improvements were made to the factory tune in the 08.5 and 09 cars, I would like to revisit tuning out PT Knock.

Where the OP has ztuner's sledgehamemr approach to tuning out partial knock (ie. pull lots of timing), here's jahman's fine chiesel approach to the PT Knock fix...please feel free to compare this to ztuner's figures, along with your current timing to get a sense of what is being done. You can EASILY see the changes graphically in ATR's Ignition Tables: Ign Table - Low Throttle/CL (No Knock):


37.50 37.50 46.70 51.10 53.50 54.60 58.10 62.90 63.10 60.00 50.80 52.20 44.80 49.00
24.50 31.90 39.70 39.00 40.80 40.90 40.80 40.80 40.70 41.00 42.00 42.00 38.00 40.50
26.00 32.00 39.00 39.00 39.00 39.00 39.00 38.00 34.40 34.00 39.00 35.00 37.00 39.50
23.00 31.00 38.00 38.00 38.00 37.00 35.50 31.50 28.10 29.00 34.00 32.00 28.00 32.00
15.90 20.50 26.50 29.00 30.80 31.50 30.00 25.00 25.60 24.00 27.00 25.00 25.00 25.00
7.50 11.50 20.50 24.50 26.50 28.00 24.40 23.70 24.60 20.50 23.50 21.50 21.50 21.50
4.00 5.00 10.40 19.80 22.10 24.50 22.50 22.10 21.00 18.50 22.50 20.50 20.50 20.50
3.50 0.50 5.70 13.20 17.40 21.50 19.50 20.30 18.00 15.00 21.50 19.50 19.00 19.00
3.20 -2.00 3.20 8.20 12.10 14.00 17.00 17.00 16.50 14.00 20.50 18.50 17.50 17.50
2.20 -3.00 0.80 5.60 11.00 13.00 15.00 15.00 15.50 13.00 19.50 17.50 16.00 15.00
1.20 -4.00 0.00 2.00 8.00 10.00 14.00 13.50 14.50 12.00 18.50 16.50 15.00 14.00
0.20 -5.00 0.00 -0.50 8.00 8.00 10.00 12.50 13.50 11.00 17.50 15.50 14.00 13.50
-0.80 -6.00 -1.00 -1.50 6.50 7.00 10.00 11.50 12.50 10.00 16.50 14.50 12.50 13.50
-1.80 -7.00 -2.00 -2.70 4.00 6.50 9.00 10.50 11.50 12.00 15.50 13.50 12.00 12.50
-2.80 -8.00 -3.00 -4.00 2.00 5.50 8.00 9.50 10.50 11.00 14.50 12.50 11.50 11.50
-3.80 -9.00 -4.00 -4.00 0.50 4.50 7.50 8.50 9.50 10.00 13.50 11.50 11.50 10.50
-4.80 -10.00 -5.00 -5.00 0.00 2.00 6.50 7.50 8.50 9.00 12.50 10.50 10.50 9.50
-5.80 -11.00 -6.00 -6.00 -1.00 -0.50 5.50 6.50 7.50 8.00 14.00 9.50 9.50 8.50
-6.80 -12.00 -7.00 -7.00 -2.00 -1.50 4.50 5.50 6.50 7.00 13.50 8.50 8.50 7.50
-7.80 -13.00 -8.00 -8.00 -3.00 -2.50 3.50 4.50 5.50 6.00 12.50 7.50 7.50 6.50
-8.80 -14.00 -9.00 -9.00 -4.00 -3.50 2.50 3.50 4.50 5.00 11.50 6.50 6.50 5.50
-9.80 -15.00 -10.00 -10.00 -5.00 -4.50 -1.50 -0.50 0.50 4.00 10.50 5.50 5.50 4.50
-10.80 -16.00 -11.00 -11.00 -6.00 -5.50 -2.50 -1.50 -0.50 3.00 9.50 4.50 4.50 3.50
-11.80 -17.00 -12.00 -12.00 -7.00 -6.50 -3.50 -2.50 -1.50 2.00 8.50 3.50 3.50 2.50
-12.80 -17.50 -13.00 -13.00 -8.00 -7.50 -4.50 -3.50 -2.50 1.00 7.50 2.50 2.50 1.50
-13.80 -17.50 -14.00 -14.00 -9.00 -8.50 -5.50 -4.50 -3.50 0.00 6.50 1.50 1.50 0.50
-14.00 -17.50 -15.00 -15.00 -10.00 -9.50 -6.50 -5.50 -4.50 -1.00 5.50 0.50 0.50 -0.50
-15.00 -17.50 -15.50 -16.00 -11.00 -10.50 -7.50 -6.50 -5.50 -2.00 4.50 -0.50 -0.50 -1.50


FWIW, both of these have been tried and tested. Either one works for some but not all. So of course, the CDN approach is a compromise between the two.

The theory behind this is that the factory tune runs "hot" @ PT with lots of timing to increase Exhaust Gas Temperature (EGT), thus increasing exhaust flow speed and improves throttle response by spooling up the turbo faster. As you remove intake and exhaust restrictions (ie. with intake and downpipe), you have already improved the spooling response of the turbo such that any timing advance from the factory tune may increase the knock counts seen. It is being theorized that as you imrpove WOT response with power mods, that it is a good idea to tone down a bit of the PT timing for the sake of longevity.

After some testing, another approach will be posted that reflects changes made to an 2008 CDN MS3. Things are looking good so far...:bana

[PSI Tuning]

If you remove the EGR and/or bypass it electrically or in a way the ECU doesn't know about then of course it will knock. The ECU has an EGR advance table so it starts operating the EGR solenoid and advancing the timing for better fuel economy. Contrary to popular belief, removing it brings few performance gains.

-Michael

[Fobio]

despite what ztuner is saying with his situation, the point of this thread is not to advocate for an EGR delete, but rather for the better understanding of why and where the car knocks and how to mitigate it thru tuning. no doubt certain cars out there have a mechanical source of knock...