Huge dip in timing questions

[Slowrc]

I was logging my truck at light throttle and felt a fishbite/miss a few times during the log. Upon review, there is no KR, but the timing dips from 30's to -10. It happens " at times" , so it is not all the time, but such an event under lots of boost and spraying meth could have been what took out my old engine. What would make the timing dip so drastically ? I will post the log later when I can. THANKS!

[Gregs]

I was logging my truck at light throttle and felt a fishbite/miss a few times during the log. Upon review, there is no KR, but the timing dips from 30's to -10. It happens " at times" , so it is not all the time, but such an event under lots of boost and spraying meth could have been what took out my old engine. What would make the timing dip so drastically ? I will post the log later when I can. THANKS!

you know I've had the same problems, I never figured it out. The only thing I found was my ac was taking a lot of spark away on the highway so I deleted that spark reduction and it runs fine. I tried logging the spark pids to see what was commanding the reduced timing but it never would act up when i was logging them.

[Slowrc]

14501

14502

log and tune for any that want to see.

[joecar]

To me it looks like those spark dips are caused when either of these happen ( I could be wrong ):
- increase in airflow (seen by increase in TP);
- engine spins down at closed throttle;



if you log DYNCYLAIR you can follow the spark tables (using scantool->tunetool cursor linking).

[Slowrc]

will you elaborate on this please...
if you log DYNCYLAIR you can follow the spark tables (using scantool->tunetool cursor linking).

Also, did you see the dip from 27.5 to -10.5 and back to 26 all in 3 fromes. What table has the power to pull 37.5 dgrees? The low timing table in the high air flow/idle rpm is the only place I can see that would pull that low. I am puzzled. I definitly need some timing logging and correction training!
THANKS!

[joecar]

Goto B5913 HO spark table... hover the cursor over the horizontal axis, a yellow box showing the link pids will appear...

if you log any of the link pids, then when viewing the log file in the scantool, open the tunetool and goto B5913...

then observe that the cursor position in the scantool links to a cell in the tunetool table...

[joecar]

More info on linking:


In tunetool go Edit->Properties->Scanner and checkmark both items under Pid Data Links.

Also, scantool units on Data tab must match the tunetool units...
- in scantool, on PIDs tab set pids to Metric (highlight, rightclick->Metric),
- in tunetool, go Edit->Configure Display Units and set tables to Metric.

...

[Slowrc]

Thanks joecar!

[Slowrc]

14511

Here is a log where I put the min timing at 5* and you will notice when it dips it goes straight to 5. There seems to be no cause. I can't find or figure why it would dip so drastically for no apparent reason.

ANYBODY ???

[joecar]

Hmmm, interesting...

are any of these activating:
- traction control..?
- torque reduction...?
- burst knock...?
- A/C timing...?

you can log the EST_*_DMA pids to see where timing is going.



edit: added (thx Slowrc).

[Slowrc]

Yes Sir, I will log those. I found the a/c timing reduction and there is some crazy reductions on certain parts of that map. Also, some of the traction control parameters were not zeroed out, probably overlooked when I swapped my tune over to a 4.8 recently . I am interested to diagnose this though because a few others on performancetrucks.net have had the same issue and I would like to resolve it for us all.
THANKS, Rodney

[HellKnightHicks]

Im having a very similar issue At high RPM. I have Disabled BTM and am going to try that and see if it helps.

[EagleMark]

Yes Sir, I will log those. I found the a/c timing reduction and there is some crazy reductions on certain parts of that map. Also, some of the traction control parameters were not zeroed out, probably overlooked when I swapped my tune over to a 4.8 recently . I am interested to diagnose this though because a few others on performancetrucks.net have had the same issue and I would like to resolve it for us all.
THANKS, RodneyDid you ever zero this and test? Although this table is under Idle and marked as AC, it does not mean it is correct.

What about Cat Protection? I can't find what it does, just temps for on off etc...

[ScarabEpic22]

Did you ever zero this and test? Although this table is under Idle and marked as AC, it does not mean it is correct.

What about Cat Protection? I can't find what it does, just temps for on off etc...

Cat Protection will dump fuel if the PCM/ECM thinks the cats are getting too hot. After a few back to back WOT passes, you'll see commanded AFR/EQ go WAY rich. If you dont have cats, turn it off.

[HellKnightHicks]

Why would the A/C require a retard in timing?

[EagleMark]

Thats a reason I find the table suspicious...

[joecar]

A/C is an increase in load, but this is only significant at low load.

[EagleMark]

With a load it would want to increase timing to compensate?

B4369 says "Maximum amount of timing that can be retarded due to A/C clutch turn on/off torque control."

So what does this table actually do? Can't see the amounts in cells ever being used? If they were that high the motor would stall, so the limits would have to be much lower then there! Just makes no sense?

[HellKnightHicks]

Thats a good ?

[HellKnightHicks]

Soo it looks like BTM is the reason that my timeing is getting pulled... but i alerady disabled it in the tune. Why is it still effecting my system?

[joecar]

Post some more logs.

Also post some screenshots of the BTM tables.