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View Full Version : LS1B... Confused by Log vs Tune


Wheelz
May 10th, 2013, 10:33 AM
Took a road trip this week pulling a light cargo trailer. Figured I'd take a couple logs and try to get an idea of what my trucks doing. Now I'm more confused :eek:

(sorry for the long log file)
So if I make a custom Map in the scan tool to look at my commanded spark (gm.dyncylair vs rpm, plotting avg values), I don't understand why its commanding what it is. It seems reasonable on the left hand side of my data when looking at the map plotting avg cell values, but as air/cyl increases so does the discrepancy between logged and the tune; to the point that the 0.6 gram/cyl column has more timing than the high octane table commands, and I filled up with ethanol free 87 octane :ermm: I also had an incredible amount of knock detection in my opinion when I was cruising in O/D. Can someone point me in the right direction to help me understand how timing is calculated? I believe I was running in P/E mode based on MAP PSI, which is what I was blaming for the knock while I was driving, till I saw how high my timing was compared to the base tables.

I don't have my LC-1 installed yet to have any WB02 data :wallbash: Truck has 91k mi and is all stock.

My tune is 99.9% stock to my knowledge as far as fueling and spark goes. I've mainly been changing shift points, torque limiters, and added a little throttle at idle cause it was stumbling on occasion when I stopped in gear. Updated to the newest software and firmware the day before the trip.

Thanks in advance


1502515026
joecar
May 10th, 2013, 01:03 PM
Post screenshots of your maps (first, goto map properties, and on each of the Data/Col/Row tabs checkmark Show Units).
Wheelz
May 10th, 2013, 04:30 PM
Sorry, here it is

15033
Mikz86ta
May 11th, 2013, 05:30 AM
Not to confuse you...but is there any word on weather that motor has false knock or ghost knock? I remember earlier 4.3L's had a problem with balance shafts causing a false knock at certain RPMs. Tho my 2003 has internals developed by GM to reduce that chance, I still think mine has some.
Also consider MAP, IAT also have input as to timing adjustments.
Wheelz
May 11th, 2013, 07:57 AM
Not to confuse you...but is there any word on weather that motor has false knock or ghost knock? I remember earlier 4.3L's had a problem with balance shafts causing a false knock at certain RPMs. Tho my 2003 has internals developed by GM to reduce that chance, I still think mine has some.
Also consider MAP, IAT also have input as to timing adjustments.

It wouldn't surprise me if it had some ghost knock. In the back of my mind i was kinda hoping it was something like that and could maybe be tuned out. I feel like it takes spark too long to recover from a knock. Is that just me?

Yes, I'm trying to track that down, I just didn't expect it to make that much difference. I just logged some different PIDs today hoping to help me figure this out

Also I think I just figured out that every time the A/C compressor starts it cuts my timing almost in half. I'm getting ready to go through my tune again to see if that's adjustable.
Wheelz
May 11th, 2013, 06:38 PM
The ac pulling timing is fixed.
I guess now I just need to get my WB02 sensor hooked up to figure out what my fuel actually is doing. I added a couple degrees to my low octane spark and I believe I noticed more activity on the knock sensors, but ill have to sit down and compare the logs to be sure.
Mikz86ta
May 13th, 2013, 03:03 AM
Where did u fix AC timing pull?

WB02 is good idea :)
Wheelz
May 13th, 2013, 04:42 AM
Where did u fix AC timing pull?

WB02 is good idea :)

I'll get you a table number tonight, but it's in the idle folder and then A/C subfolder. I set max spark retard to 0*
Mikz86ta
May 13th, 2013, 05:05 AM
B4369 maybe?

Mine is 0 except from 30-80 kPa and 400-3600 RPM area of the column and rows. Starts at 20 and high as 50
Wheelz
May 15th, 2013, 02:40 AM
Sorry, I've been busy these last couple days. I haven't had a chance to look at anything, but that sounds like the right table. I just zeroed it.