Timing pulled on 2nd to 3rd shift!?!? Have tune and log available - LS1TECH - Camaro and Firebird Forum Discussion

Go Back  LS1TECH - Camaro and Firebird Forum Discussion > LS1-LS2-LS3-LS6-LS7 PERFORMANCE > PCM Diagnostics & Tuning
Reload this Page >

Timing pulled on 2nd to 3rd shift!?!? Have tune and log available

Notices
PCM Diagnostics & Tuning HP Tuners | Diablo | Pantera EFI
Sponsored by:
Sponsored by:

Timing pulled on 2nd to 3rd shift!?!? Have tune and log available

Old 11-01-2018, 04:28 PM
  #1  
On The Tree
Thread Starter
 
neblackshirts's Avatar
 
Join Date: Apr 2016
Location: Lincoln, NE
Posts: 191
Default Timing pulled on 2nd to 3rd shift!?!? Have tune and log available

As title says not sure why timing is being pulled on shift. Car pulls good from 1st to 2nd but falls flat into 3rd. I will post Tune and full throttle log where you can see the timing being pulled. This is a 3.73, Built 4L60E, & 3600 stall Yank converter behind a LQ9 408.

Maybe someone can find where my mistake is at.
neblackshirts is offline  
Old 12-07-2018, 11:33 AM
  #2  
Launching!
 
Join Date: Jan 2018
Posts: 237
Default

its falling flat on its face because all your spark is being ripped out as it goes into 3rd. I would suspect this is the PCM over riding your maximum knock retard table edits to 0 and using an alternative retard to protect the engine from what the knock sensors are reporting. to confirm this you'd have to log more spark retard PIDs. I personally have had to switch the sensors off, zero max retard, max the sensor gains and also zero the general knock retard tables to stop the knock sensors influencing timing. just one of those steps im my experience still lets the knock retard strategy influence timing corrections.

I would suggest turning that all back on and seeing what happens.

your log clearly shows the flare/slip in 2nd gear when the TCC applies. a big flare like that will cook the clutch pretty quickly.
Luke19901 is offline  
Old 12-07-2018, 12:08 PM
  #3  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 7,967
Default

I didn't open the files but do you have torque management on? Typically that will happen on the 2-3 shift unless you zero it out. It should be pretty easy to tell if its from knock or from torque management.
ddnspider is offline  
Old 12-07-2018, 12:31 PM
  #4  
On The Tree
Thread Starter
 
neblackshirts's Avatar
 
Join Date: Apr 2016
Location: Lincoln, NE
Posts: 191
Default

Yeah Torque Management is disabled, transmission has about 600 miles on rebuild due to breaking a reverse sprag coming off a Dyno run. Had a local shop go through it but it was a Finish Line Transmission lvl 5 with a Yank 3600. Luke19901 mentioned flare/slip and might make some sense because last couple times driving car it felt funny and had a burnt clutch smell after a wot 1st through top of 2nd pull.

This falling on it's face problem has been an issue for a long time now. Some said it was a fuel issue and some a torque management issue. I've kind of ruled out the fuel issue due to it never gets lean at wot.

Dumb question but from looking at the log how can you tell it's flaring or slipping?
neblackshirts is offline  
Old 12-07-2018, 12:54 PM
  #5  
Launching!
 
Join Date: Jan 2018
Posts: 237
Default

look at the RPM and VSS in the log as it goes to second gear. the RPM drops and begins to pick up again and VSS continually increases right after the 1-2 shift. shortly after that you can see the RPM basically hump... it increases then flattens out then decreases. the VSS follows the same curve but more aggressively. the flat area is where the clutch is slipping before pulling the RPM back down upon applications where the RPM and VSS begin to become linear to one and other.

that means you're asking the TCC to lock too soon. there is too bigger difference between engine RPM and trans input RPM. picture sitting in a manual car stationary and selecting 3rd gear, revving the engine to 2500RPM and slowly taking your foot off the clutch until it moves. that's more or less what you're doing to the TCC in your car. if you wish to engage the TCC at WOT you need to do it at a point where converter slip is as close to 0rpm as possible. if that point doesn't present itself anywhere in a WOT pull then you're converter is junk and slips far too much.

as for falling on its face, look at your log. immediately at the 2-3 shift the timing is reduced to -1.3 degrees from the 24 it had at the end of 2nd. at a guess that would be around 200rwhp your log shows you loosing in an instant
Luke19901 is offline  
Old 12-07-2018, 01:25 PM
  #6  
On The Tree
Thread Starter
 
neblackshirts's Avatar
 
Join Date: Apr 2016
Location: Lincoln, NE
Posts: 191
Default

Yeah I seen the timing being pulled on the 2nd to 3rd shift and then slowly added back in. I was assuming that this was happening due to something in the torque management somewhere engine? or transmission? but why does this only happen on 2nd to 3rd and not on the 1st to 2nd wot pull?

Isn't the VSS basically an input for tire gearing? I was having an issue with a no shift issue bouncing off limited going from 2nd to 3rd. So I lowered my commanded MPH and seemed to fix that issue but could this have screwed with the VSS?
neblackshirts is offline  
Old 12-09-2018, 02:12 PM
  #7  
On The Tree
Thread Starter
 
neblackshirts's Avatar
 
Join Date: Apr 2016
Location: Lincoln, NE
Posts: 191
Default

Originally Posted by ddnspider View Post
I didn't open the files but do you have torque management on? Typically that will happen on the 2-3 shift unless you zero it out. It should be pretty easy to tell if its from knock or from torque management.

Iím not sure but think knock is turned off. I would think more of a torque management issue if itís not happening in the 1st to 2nd shift but I could be wrong on that.
neblackshirts is offline  
Old Yesterday, 01:17 PM
  #8  
Launching!
 
Join Date: Jan 2018
Posts: 237
Default

I would suspect its the trans torque management. you're asking for 25% torque reduction on the 2>3 shift at the estimated torque the PCM has calculated. 24 commanded minus the 26 from 25% of torque lost in spark retard vs torque % lost table is damn near what's logged. in the scanner.
disable trans torque management by populating the 2 torque reduction tables with zero.

in the engine torque management set the spark retard vs. torque reduction % table to zero also.

that will stop it falling on its face after the 2>3 shift. you man need to use shift time and pressures to soften the shift with no torque reduction depending on personal preference.
Luke19901 is offline  


Thread Tools
Search this Thread

Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: