fighting negative KR

[_scorpion_]

hi all,
since some time I 've been trying to get rid of negative KR I get. This already appears only at cold start and before the engine (coolant?) warms up and it get down as low as -15 (even -20) at light throttle; after coolant is 85+C - it's almost clean, very few negatives no more that -2/-3.

i've already trying to increse VE, change spark, etc, no luck. i'm very much confused that it only happens at cold engine - suspect gains/additives, but cannot figure out which one(s). any help appriciated.

(it's about jeep gc 6.4 supercharged)

1.png

full log attached just in case.

cold_drive.hpl

[EM PERFORMANCE]

Log all your timing channels ECT advance, IAT advance, etc.
Log all your retard channels: short term knock, long term knock, total spark correction
everything all channels related to timing
Check torque management
If your VE is good and timing also then you can datalog with all the timing channels and observe all them youll find whats pulling timing
You can also slowly decrease short term knock on the Retard TAB but you have to make sure other stuff isnt taking timing away

[_scorpion_]

All timing possoble (on top of what I can do) is logged; it is knock retard that is pulling timing - again, only at cold engine, when at normal pperating temp - all's fine, or next to it.
Not sure on what you mean in terms of "check torque mgmt"

[SiriusC1024]

Knock is more prevalent at colder engine temps; however, I'm seeing -6 KR even when the engine is at 185F at time 04:24:46.

Spark is probably too hot entirely, and an ECT multiplier is making it worse. Hard to tell without the tune file.

[_scorpion_]

Hi SiriusC1024,
thanks for feedback.
The tunefile is no secret - I attach the current one here in case you can do me a favor and drop a glance on it.jgc2014_sc_v15.hpt

[SiriusC1024]

Yeah there's an ECT spark modifier. See how the cold spark is adding spark and hot is removing? Same with the IAT cold spark modifier.

So maybe try zeroing those cold corrections out. The hot spark is there for pre-ignition safety if the engine gets too hot.

[_scorpion_]

thanks; I shall try that out definitely.

[_scorpion_]

nope gents, that did not help. my ect and iat spark correction table are zeroed, but retard is still huge. totally lost.

below are two logs: same tune, same weather, same car, same rpm, inj duty, tps, ... nearly all!!! the ony diff I see - is ect and iat. in case of "cold car" - huge retard (knock retard short term), in case of warm car - all clean and clear. wtf? what and from where is timing being pulled???

cold.png

warm.png

[_scorpion_]

well, guys, since no other reply, I shall just sum up what I've figured out playing with different settings and reading the forum:
some people write here that the Mahle pistons rattle a lot at cold engine; as long as I have them installed in my engine, and given the fact that I have huge negative kr at cold while almost clean at warm engine - I desensitized the knock sensors bumping voltage up to ~2.5v at around 1800-2500rpm. This help a lot; it did not clear the problem totally (at cold I have knock sensors hitting 3.7v sometimes) but at last it decrease the kr so that it does impact drivability. again, with warm engine it is all ok.

sum this up just not to keep the thread "open-ended". cheers.

[drumnbasslvr]

Since no one else will say I'll help. Get into the throttle tab and make the whole feedback control proportional table a 1.0. You're supercharged. That's how it is gonna be. Also with this change you'll notice less jitter when you're cruising and you're right at below or above the 100kpa mark. Next engine diag>torque correlation. Raise torque delta and torque delta fault to 900. I see 1933 in there so someone has been diablo tuning this. Leave the others below it alone to stock. Lastly, raise the engine torque adapt values to -900 or 900 respectively depending on if it has a negative or positive number in there to begin with. Do the frictions and the transmission ones. Reenable spark of torque management, you'll kill your transmission without it there. Put your catalyst temps and overtemps back to stock. Don't melt a piston. You'll have joy with this change. I promise. There's plenty more wrong with your tune but this will help you learn to get in the right direction.

Jeez just give him the answer! It's not black magic! Evans, Tuning School, nor HP Academy give this advice.

[rays04gtx]

Been super busy myself, Mahle Pistons when installed properly will bang around a bit when cold, but not enough to pull 16* of timing,

attached is a copy and past over to your tune from a 2013 Jeep we did a few years back wasn't pulling timing like yours but the Shop that built it had excessive piston to wall clearance on the rebuild...also the SC on that Jeep was a Kenn Bell 4.7l

the Difference between Tune (1) and (2) is the PT timing table, I think some of your issues stem from the Timing curves, personally if it were me everything from .25 Aircharge and under out to 15-1800RPMs would be reduced another 20-30% and then smoothed out the whole table

[_scorpion_]

Wow, thanks a lot for that, I shall chase that out. Indeed, it used to be diablo tuned before.
Just one note that cat and overtemp were zeroed due to I have no cats , with long tubes instead. That's a lot again, I shall be trying thing and get back.

[_scorpion_]

Will study that's, thanks as well!

[PurpleRam]

Wow, thanks a lot for that, I shall chase that out. Indeed, it used to be diablo tuned before.
Just one note that cat and overtemp were zeroed due to I have no cats , with long tubes instead. That's a lot again, I shall be trying thing and get back.

When I pull cats off, I Max the temps , at 0 the ecu thinks the cats are getting too hot

[_scorpion_]

pardon if get you wrong, but this is what I have in temperature fields, it's maxed already; the what is zeroed - are enrichment tables only;
temp.png

as well, I do not get the idea about torque correlation; these are my values, it is nowhere 1933:
tqdelta.png
Unless it's a wrong place I look - I'd be very much surprised if we see different value in same fields.

For Spark TqMgt - already turned back to `enabled`, thanks for noting.

Will test the rest tomorrow or day after.

[_scorpion_]

interesting idea about the p/t spark table; and very nice one in the Aa1(2) file, comparing to the first one (which is the same I have now). I shall work on this, but not to mix all togather I shall go progressively - check the things drumnbasslvr advices, and then work on "nicing" the p/t spark. One question if I may - when/after changing the spark table - shall I nee to adjust the VE tables as well?