What causes these 10-12 degree down spikes in cruise timing on my scan.

[Doug Doty]

How can I figure out what causes these down spikes in the actual logged timing. On this log the last minute or so was cruising through a small town on cruise control at 44 ish mph and I keep seeing the timing drop to high teens of degrees when the top flat area it spends the most of the time is 33-34 degrees. I would like to get to the source of this. What parameter could I consider logging to find the driver of this down spiking. I will have to come back and edit: posted wrong fill and cannot find the right one

ddd.hpl

[TCSS07]

Do you have ac on?

[Doug Doty]

I realized I had posted the wrong scan log. Just went out and duplicated it and and edited my original post. I double checked the AC question and this one is without.. I got a feeling this is not unusual for some reason but just feel the burn to get to the bottom and understand and or fix this...

[TCSS07]

post tune file
also why your iac reading max?

[Doug Doty]

Here it is. I am too green to understand you comment about IAC. My channels are copied from the tuning school web site downloads to get me started until I figure out what all to monitor so there is admittedly a couple I do not actually understand.

1500hd tuneup 2nd try.hpt

[TCSS07]

you still have torque management on - disable spark retard and torque loss % - zero them out - raise max torque vs rpm to max - raise the values under tip in torque to max - disable abuse mode and re check
you said you didn't have ac on? or at least defrost because defrost will use the compressor because if so disable ac bump torque spark - under spark advance at the top and re check

[Doug Doty]

Thanks for the direction, I removed 3/4 of the TQ Mgmt in the trans section for now and a first step. No hvac at all on during that scan log. I was not sure about that 9 digit # in those cells in the Engine TQ Mgmt. section.

[TCSS07]

Yeah those numbers are pretty redick lol if you dont want to put them to max thats fine you just put them high enough so the ecm wont pull any torque

[Jason B]

It has an electronic throttle so the IAC counts aren't actually anything. It's a dead channel.

It's not a/c bump torque spark either. Not torque management at those speeds and rpm, although I'd delete it 100%.

[Doug Doty]

I really appreciate the help and advice. I done the 75% TQ reduction and raised the 1-2 and 2-3 shift points 3 mph through the low to mid range and it feels a lot better to drive. I have went back now and killed the TQ Mgmt. in the Eng and trans parameters and added a half tank of 93 to start on the next step of optimizing timing. Engine developed torque is up to 315 -320 now. When I get done I will swap all the way back to stock tune and do a comparison but is was closer to 290 295 at first.

[TCSS07]

is it still dropping timing

[Doug Doty]

Yes no change, sorry should of said... Runs along on CC ar 55 mph on the flat and just random drops from 30 to 17 approx on both ends. no change from the 75% reduction in TQ Mgmt. Total TQ elim. in the morning and another test drive I got a 70 mile trip...

[TCSS07]

post current file with changes made
try one more chart because like i said i ran into this problem before and it was the ac table / under t/m - engine - max retard (bottom left column) even though you don't have it on im wondering if its still playing a roll because it seem to be some sorta of t/m reduction - just zero it out before your next drive and recheck

[Doug Doty]

It is gone now that i wiped out all tq mgmt. not sure what was driving it. I am working my way towards a small turbo to boost towing torque and having 20? swings in timing was not gonna work. Thanks for you help !! I am heading to Milwaukee this weekend to the real tuners tuning class that James Short and Scott Clark Are putting on at Endless performance so hope to get a little better informed there too.

1500hd tuneup pe on Tq mgmt gone.hpt
gggnoac.hpl

[TCSS07]

awesome glad to hear and yeah i wouldn't like random timing swings either, stupid ecm lol

[5FDP]

The timing swings weren't hurting anything though, so it's not like that was some sort of bottle neck. It's just part of the calibration. Just more of an annoying thing if you care about it.

[Doug Doty]

I am used to tuning outlaw style drag cars so to me it is unacceptable to ignore it. Since this is a stockish application for now and I am just learning I kinda figured it was no big deal but just could not figure out why it would do something so silly or accept it. I can live w/o torque Mgmt if it is going to do silly things like that at steady state speeds. I am used to looking at Speed Pro and BS3 that seems less twitchy.

[scoob8000]

If your still curious, in the scanner go to add pids to log and search for timing. There's a handful that will show you what is adding or removing timing.