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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.
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.
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.
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?
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
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?
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.
I’m not sure but think knock is turned off. I would think more of a torque management issue if it’s not happening in the 1st to 2nd shift but I could be wrong on that.
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.
Thanks for the feedback, I enjoy trying to learn and understand this stuff. I was wondering if a lot of tire spin would make the TCC appear to be slipping? On that WOT log I did break the tires loose as the road wasn't the best surface. Talking nice weather 50s around me and I'm kind of dying to make some of the input changes suggested as I think the 408 has power and pulls hard out of the hole then as seen falls flat on its faces due to timing being pulled.
Torque Management most likely. If you just try to turn it off, do a Write Entire, not a write calibration only.
Its still a good idea to fix all of the tables. I've seen some weird stuff happen when the info was left in there.
A buddy of mine grenaded an engine when he thought he had TM disabled and timing was dropping to -14* (absolute) on the shift with 20 PSI of boost.
Transmission torque management doesn't act like that. If it was TM it would only be a quick timing retard, as soon as the shift was completed the timing would return to normal immediately (not gradually).
This is what TM does:
It’s probably your burst knock. Mine was doing the same thing the other day. I limited burst knock max retard to 5 degrees and took one level out the sensitivity and changed how fast it ramps back in if it doesn’t see knock. I don’t see any retard anymore. May blip .1 degree from time to time.
If I was having any type of KR wouldn't it show even if it was a quick knock?
read up on burst knock. It’s not actual knock. It’s predicted knock.
knock sensor level vs rpm vs cyl I added 1.5 to 3200 rpm and up. The cam causes false knock. I retarded the timing several degrees and it did not change until I decreased the sensitivity.
Burst knock retard vs ert vs ect From 194f to 285f I highlighted all those cells and hit negative on the keyboard once. To lower the value by just one.
Maximum knock retard vs rpm (in power enrich) I made it (4) from 2400 to 8000
knock retard recovery rate. I made 2400, 2800, 3200 (.031)
4000-8000 is (.026)
i only made these changes after retarding timing. When I get real knock (I can hear it, my car is pretty quiet) I’ll see knock retard.
Also theres two areas of tq management. Engine and transmission. Make sure you go to the transmission section. Click tq management. Then under torque reduction, click normal. And take note of what is in those cells. I have mine pulling some on the 1-2 and 2-3 shift because if i didn’t, the tq from this motor will eat my trans, for a snack. Lol.
OK so between work and family plus holidays rolling in finally did a little reading on burst knock. So if I'm understanding burst knock correctly it's not a bad thing problem wise, but the ecu is saying with the huge jumps in airflow knock is a strong possibility. Burst knock is basically anticipating knock even if it doesn't happen. I posted a small bit of my setup motor thinking maybe given cam spec that it could be producing these false conditions. So that would explain further my need to back off TQ management.
Heads - AFR Mongoose 230cc / 62cc
Intake - FAST 102MM
Throttle Body - NW 102MM
Cam - Comp 243/251, .624/.624, 111+1 LSA, 110 ISL
This is on a 408cu with 11.1 compression
torque management is up to you. some guys run none, some guy run factory. some guys run 50% less than factory.
personal preference really. if you have a stock driveline and big power/torque engine its advisable to use some. in stock or close to stock form they often last with no torque management.
torque management is up to you. some guys run none, some guy run factory. some guys run 50% less than factory.
personal preference really. if you have a stock driveline and big power/torque engine its advisable to use some. in stock or close to stock form they often last with no torque management.
Drivetrain wise I'm running a built 4l65e, yank 3600, mark williams driveshaft, and 12-bolt w/ 3.73. Kinda worried as it was mentioned by someone that converter is flaring or clutches are slipping with that log I posted. But it did have a bit of wheel spin so maybe that’s what looked like flare or slippage in the log to others?
what would trigger burst knock from on the 2nd to 3rd? Is it because of the heavy load by that point where as is moves through first into second quicker.
a built 65E and stall should be fine with 0 torque management. you just need to make sure you have the shift calibrations right so there is no slip or shift overlap etc.
you also need to be on point with your TCC lock up. you cant ask for lock up when the converter has big slip % or you'll wreck the TCC. especially with a heavy car.
personally I leave the TCC unlocked full time until the shift calibration is spot on. then I gather some WOT data to see where converter slip is low enough (if at any points under WOT, often there isn't any points with low slip at WOT) to apply the TCC. the I use that data to populate the points at WOT I want the TCC locked.
then I usually populate the points at cruise under light throttle I want the TCC locked for fuel economy.
I personally disable burst knock in all cars. I wouldn't worry about doing that. will save you guessing where your timing is going
Ok finally had a free minute to look at stuff. Going through my tune file had a couple questions on a few things I might have noticed.
First under the transmission - torque management - torque reduction- normal, should I have those all zeroed out?
Second I noticed under auto shift properties general and then my force motor current in the 100 column I have it set the same as 96 column which is set at 83, should I have those maxed out like I do for the zero column which is set at 1,069?
Third under the engine column torque management and general then at the spark retard versus torque reduction should I have those all zeroed out it currently starts at nine and goes up to 50?
just curious if this will help me out at all or if any of these raise red flags to you guys that know what the hell is going on lol
Last edited by neblackshirts; Jan 4, 2019 at 11:02 PM.
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Timing pulled on 2nd to 3rd shift!?!? Have tune and log available 
