Pulling timing in first gear before the shift.
Thread Starter
Burning Brakes
Joined: Apr 2010
Posts: 1,001
Likes: 37
From: Farmington Missouri
Pulling timing in first gear before the shift.
Basic stats: 416, YSI, Fuel System, Circle D, 8l90. My car has always pulled 10* + timing (through torque management) when it hits 5500rpm in first gear, causing the car and RPM's to lower/slow down. It will also do it sometimes in 2nd and 4th. Attached is a log showing what I mean. Any info on what it could be? I don't want to turn torque management completely off and grenade the trans.
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
Perhaps your torque demand tables do not reflect your mods. I've seen LS/LT motors go so far as closing the throttle blades. It's not torque management to save the trans, it's torque modeling for the calibration. If not updated, the engine will be able to produce more torque than planned and will actually reduce torque output (by timing and then throttle) in order to compensate.
Let's say your motor in stock form made 450 lb-ft of torque at 5500. Now all of a sudden due to your mods it's making 550. It knows this and will try to scrub off 100lb-ft to get back to the torque target.
Just a hunch until a knowledgeable tuner comes along to chime in!
Let's say your motor in stock form made 450 lb-ft of torque at 5500. Now all of a sudden due to your mods it's making 550. It knows this and will try to scrub off 100lb-ft to get back to the torque target.
Just a hunch until a knowledgeable tuner comes along to chime in!
Last edited by davepl; Oct 16, 2017 at 12:25 PM.
Thread Starter
Burning Brakes
Joined: Apr 2010
Posts: 1,001
Likes: 37
From: Farmington Missouri
I appreciate the feedback. I tried to log every predicted and actual torque I could find in the scanner. My predicted and actual torque seems to be nearly dead on, which is why I don't understand the huge timing pull. Would that be in the Virtual Torque/Coefficient tables? I tried to adjust the virtual torque at 800mg airmass (which it always sees well more than that) and it was still doing the same.
Drifting
Joined: Apr 2015
Posts: 1,276
Likes: 317
Are you logging pedal position and actual Throttle position as well? If so, do you have any discrepancies there? Again, that would be a function of driver demand and commanded torque. I would post logs and the tune, hopefully T/A Kid and/or Higgs will take a look and chime in 
Thread Starter
Burning Brakes
Joined: Apr 2010
Posts: 1,001
Likes: 37
From: Farmington Missouri
Are you logging pedal position and actual Throttle position as well? If so, do you have any discrepancies there? Again, that would be a function of driver demand and commanded torque. I would post logs and the tune, hopefully T/A Kid and/or Higgs will take a look and chime in
Last edited by Dave01GT; Oct 16, 2017 at 12:55 PM.
Racer
Joined: Oct 2016
Posts: 396
Likes: 72
Timing drop is coming during shifts. Looks like you are spinning also. Immediate Engine torque source is Trans S. I am not an expert though... still learning this stuff. Shifts look a little long also.. but I have TM dialed out on mine.. so hard to compare.
Thread Starter
Burning Brakes
Joined: Apr 2010
Posts: 1,001
Likes: 37
From: Farmington Missouri
With TM dialed out, will it still pull timing on the shift to help the trans out?
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Racer
Joined: Oct 2016
Posts: 396
Likes: 72
To me, it looks like it starts pulling timing down to 4* @ 5350 in this log, then timing comes back for a split second at the shift, then pulls timing again for the shift. It then comes back full in 2nd then does it again slightly after 2nd.
With TM dialed out, will it still pull timing on the shift to help the trans out?
With TM dialed out, will it still pull timing on the shift to help the trans out?
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
Back in the Gen 2 LT1 days I had to fix/workaround a bug in that ancient ECM where it'd fail to upshift the trans if the wheel speed sensor value was changing too quickly (ie: accelerating faster than they expected possible). Seems similar, though that was a "bug" and this is a "feature".
Racer
Joined: Jan 2017
Posts: 315
Likes: 67
Basic stats: 416, YSI, Fuel System, Circle D, 8l90. My car has always pulled 10* + timing (through torque management) when it hits 5500rpm in first gear, causing the car and RPM's to lower/slow down. It will also do it sometimes in 2nd and 4th. Attached is a log showing what I mean. Any info on what it could be? I don't want to turn torque management completely off and grenade the trans.
Thread Starter
Burning Brakes
Joined: Apr 2010
Posts: 1,001
Likes: 37
From: Farmington Missouri
Thread Starter
Burning Brakes
Joined: Apr 2010
Posts: 1,001
Likes: 37
From: Farmington Missouri
Racer
Joined: Jan 2017
Posts: 315
Likes: 67
Race Director
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