Data Log Info

[Immortal1]

New to Data Logging but not computers...
Was able to do a quick data log using the InTune DCX. Above is a screen shot from a select time in the Data Log.
My question regards understanding the KNK ST Retard trace - is what I am seeing with the trace an indication of spark knock. If so, I assume this will have an effect on the overall spark advance?

For what it's worth, I likely am running 89 octain gas (just don't remember what went into the tank last) and currently using the 91 octain DS tune.

Any feedback would be appreciated.

Edit: little hard to read values in pic.
Throttle Blade Position = 76.22 (interesting, was at WOT)
Vehicle Speed = 98.00 (closed course, professional drivers only)
Engine Speed = 5,078.0
Base Spark = 15.00
KNK ST RETARD = 3.00 (lightest colored trace)
Actual Spark = 14.50

Edit #2 - picked this up off another post on this forum.
"Knock Retard, this the amount of timing removed (in degrees) due to knock (detonation/ping). The knock sensors can in rare cases pick up other harsh engine noises as well, if this is the case it is recommended to fix the cause of the noise before proceeding.
You basically always want the knock retard to read zero under wide open throttle conditions, it is normal for it to show some KR when stomping on the throttle and also during the shift.
Monitor the spark and the knock retard pids under wide open throttle and see if you have any knock retard, anything higher than 1 should be adjusted in the respective timing range in the Predator , if the knock is severe, 5 deg plus, try lowering spark by 10%, if less than 5 deg, try 5%. Make another wide open pass and monitor the same pids and basically keep doing this until you seen no knock retard."

Now the basic question is if the above applies to the KNK ST RETARD or the KNK LT RETARD? The long term retard PID was basically zero if I remember correctly.

[nuke]

It would still apply if it were not for the unpredictable quality of our ethanol-laden gasoline…in my humble opinion.

All other things being equal, you may see all manner of short/long knock retard one day and none the next, depending on where you got the gas you were burning.

And I don’t mean Shell vs. Chevron vs. the typical Mom & Pop Shop (though that will certainly factor into the quality issue sometimes); I mean some places will not sell the higher octane very fast, and how long it has been sitting in the underground storage tanks is definitely a factor in its quality as seen from our particular perspective.

Throw in other mitigating factors such as oil vapors from the CCV system lowering the effective octane of fuel in air/fuel mixture, and you get a very unpredictable environment in which to try to operate our vehicles.

Thankfully, we have the ability to monitor our engines’ behavior in real-time to keep an eye on what is going on. And if we observe something unexpected or undesired, e.g. excessive detonation, we can then make adjustments as necessary.

For me, those adjustments usually aren’t anything as invasive as modifying the spark timing of my tune and reloading it. If I see a bunch of LT/ST Knock Retard where there was none previously, I go on the hunt for better quality gasoline and/or add some fuel additive such as ethanol treatment, etc.

Anyway, didn’t mean to get all preachy on you, just wanted someone out there to benefit from all the frustration, tears, hair-pulling, etc. I have gone through dealing with this very issue…and I am still nowhere near getting it all figured out, that’s for sure. But as a great American hero once said: “You just gotta keep on keepin’ on.”

I think those are words we can all live by…thank you Joe Dirt!

Nuke

[Immortal1]

Thanks Nuke for the info! Kinda figured it had more to do with the gas quality than anything else. Now that I understand the data logging process and how to look at it I will likely create a few different logs just to get a better idea of which stations I should avoid

[nuke]

Yeah, I would definitely advise data logging every chance you get. You can never have enough!

I create and catalog mine according to which tune was installed, then by location/brand of the gasoline seller within that. From there, I can get a general idea of which places around town are likely to have acceptable gas and when they usually will have it.

I wish the quality was more consistent between individual stations and/or brands, but I have found that is just not going to be the case. Sticking with the name brand stuff is good, but once it gets old (or whatever it is that effectively lowers its octane below its stated level) the name on the sign isn't going to keep the Knock Retard from showing up in droves.

Here's a couple of screen shots from recent log files which should illustrate the madness we have to deal with around here...

This log file was taken while running a name brand 93 octane gasoline with the 91 tune (the red and pink lines are the LT/ST Knock Retard values; the other two are vehicle speed and RPM):

DataViewer_KR.JPG

This log file was taken while running the same brand 93 octane gasoline but from different location, also with the 91 tune (the red and pink lines are the LT/ST Knock Retard values; the other two are vehicle speed and RPM):

DataViewer_KRx.JPG

Both were typical driving sessions, nothing out of the ordinary. But the first one clearly shows non-stop KR even though the octane rating of the gas should have been more than enough for the tune. I noticed all the detonation and quickly ran the gas out so I could go find some good stuff. Ended up finding some, and data logged again. As the second log shows, that batch was much better.

It's maddening trying to keep it straight sometimes...maddening I tell ya!!

Luckily, a quick trip down the road and back in my Challenger is all it takes to calm me down...which works out good, cause I'm always able to drive out any bad gas pretty quick if I run across some. HA! Take that, gas companies!!

Nuke, OUT!