gearCutState values

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amdisthebest
Posts: 17
Joined: Thu Jan 10, 2019 8:14 pm

gearCutState values

Post by amdisthebest »

Hello all,

Can someone help me clear up what the following gearCutState values mean?

Masked
Clearing

My clearing state occurs for a longer time than I'd like (about 410ms) which is causing a delay in returning engTrqEstOutputTrans back to it's normal state which is causing my DCT to have clutch slip briefly between shifts.

During the clearing state, engTrqEstOutputTrans slowly ramps back up. Just after gearCutState returns to idle, trqOutput returns to full which gives the clutches full pressure.

I can’t find anything within the gearCut module that resembles masked or clearing. I actually can’t seem to find anything in the entire cal.

Any info on this would be awesome. I assume it might be something to do with the torque module instead.

Thank you in advance,
Nick
stevieturbo
Posts: 1321
Joined: Sun Dec 07, 2008 2:04 pm

Re: gearCutState values

Post by stevieturbo »

Masked is simply the delay from a gear cut action, where it will ignore any further requests because the current action is not yet complete. Perhaps more applicable to manual or sequential type boxes, than a fully automated DCT but I'm sure it still has a place. Time delay to be decided for each user.
To avoid multiple attempts of the same request type of thing that might have been an accident or something, say hitting lever too hard, or holding the lever on etc.

Clearing is I guess it just reverting back to a normal state after any controlling actions have expired.
amdisthebest
Posts: 17
Joined: Thu Jan 10, 2019 8:14 pm

Re: gearCutState values

Post by amdisthebest »

Thank you for your response. I need to figure out how to shorten the clearing time because during that time trqOutput to the trans is ramped back in too slow.

Here's a screenshot if it's helpful at all:
Annotation 2019-02-01 085008.jpg
Annotation 2019-02-01 085008.jpg (201.22 KiB) Viewed 10970 times
stevieturbo
Posts: 1321
Joined: Sun Dec 07, 2008 2:04 pm

Re: gearCutState values

Post by stevieturbo »

I think I would be more curious as to why there is still a gear cut request active, when you're indicating what should be the power coming back on.
amdisthebest
Posts: 17
Joined: Thu Jan 10, 2019 8:14 pm

Re: gearCutState values

Post by amdisthebest »

Upon further review, it's looking like there might be something wrong/flaky with the gearCut/blip request. I have a log earlier showing a gearCut request during a pull in 2nd gear.
gearCutIssues.jpg
gearCutIssues.jpg (100.82 KiB) Viewed 10952 times
Ryan.g
Syvecs Staff - Caretaker
Posts: 498
Joined: Fri May 30, 2008 4:05 pm

Re: gearCutState values

Post by Ryan.g »

The gear cut request is a flag that comes from a Message on the TCM (Trans control Module) with DCT plug and play kit for when Torque Reduction request is Active. If the TCM is wanting to reduce the Torque this will come active and the Engtrqlim will drop also which is the parameter from the TCM to telling the torque control on the Syvecs what amount of torque the tcm wants.

The Clearing state is when the gearcut time has gone past the amount set in Scal but request is still active.

The EngtrqOutput ramps in slowly as the syvecs is doing as the TCM wants based on the Engtrqlim. You need to either pull more torque to get the TCM happy and see no clutch slip or your cluch is not man enough for the actual Engine Torque you have.

If you are making more actual engine torque then what the OEM TCM was designed to see then you need to modify the torque reduction amounts or have custom tables to pull more to keep it happy.
nmerdan
Posts: 30
Joined: Mon Jan 27, 2020 7:40 am

Re: gearCutState values

Post by nmerdan »

I'm looking at a somewhat similar thing, but my issue is that my engTrqEstOutput is 358Nm and I get a reduction from the TCM to 392Nm (engTrqLim). At that point the trqFuelSev jumps to 21.5% with a GEAR CUT as a source (there is no gear shift happening). So the torque is already lower than what the TCM is asking for, but the ECU still cuts fuel. This lasts about 100ms (need to increase my logging freq) and after that the engTrqEstOutputTrans continues to rise to the 392Nm value and after it reaches it, the ign retard is applied to maintain that torque as expected.

If I increase the fuel consumption scaling (using the alternate torque estimation), then this doesn't happen, but rather the engTrqLim comes in a lot sooner (as expected, due to us reporting higher torque to the trans), but is dealt with purely using ignition retard. This is a S7 PNP kit for the 2012 TTRS, and increasing fuel consumption scaling negatively affects shifting.

syvecs_log.png
syvecs_log.png (58.19 KiB) Viewed 8541 times
nmerdan
Posts: 30
Joined: Mon Jan 27, 2020 7:40 am

Re: gearCutState values

Post by nmerdan »

OK, I figured this is happening due to Fuel Cut defined in the "Gear Cut -> Open Loop ... -> Fuel Cut Severity" section of the calibration. As far as I understand, this is to be used with sequential gearboxes, does it also apply to DCTs? Can I simply disable Gear Cut for all gears and let the Torque Estimation and Limitation part of the map take care of torque reductions based on TCM signals?
Westillo
Posts: 9
Joined: Tue Dec 29, 2020 11:45 am

Re: gearCutState values

Post by Westillo »

nick, did you figure this out? could it be the clutch is actually slipping? I have the same issue which goes away when I lower shift rpm point. as I increase shift rpm the clearing state takes along time and shift time increase, this issue increases with rpm with me.
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