# spool vs at downshift



## Tomko (Jun 1, 2013)

Were you manually shifting the transmission or was it in drive?


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## bigluke (Aug 18, 2013)

On drive, usually it just kick in in the same time as it downshift's, it's like the at hesitated before shifting and it took forever to spool back...anyway just did it once so there's nothing bad just to see if someone else ever had this kind of at/spool lag.


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## diesel (Jun 8, 2013)

I have found that if you WOT in manual mode, you will not have much power if the RPMS are too low to be in the torque band. I was just playing with that yesterday. Nothing at around 1500 RPMS but over 2000 was good.


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## Scott M. (Apr 23, 2013)

happened to me once. Thought I was crazy but I guess it can happen. Feels weird but then it wakes up. Hope its just a hick up.


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## obermd (Mar 3, 2012)

The turbo spooling is dropped off during shifting to protect the transmission. It takes a couple of seconds for the turbo to respool after the shift.


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## diesel (Jun 8, 2013)

obermd said:


> The turbo spooling is dropped off during shifting to protect the transmission. It takes a couple of seconds for the turbo to respool after the shift.


Hmm, I am going to have to pay more attention to this. Off the top of my head, it does seem like there is a brief lag after each shift at WOT. It was never really obvious to me though. It doesn't really seem to affect the general flow of acceleration.


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## diesel (Jun 8, 2013)

OK I paid attention and it does seem like there's a slight boost reduction right after the shift, but just for about 1/2 sec


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## jblackburn (Apr 14, 2012)

If the turbo's not spooled in the first place (suddenly stomping the pedal from 1500 RPM for instance), the Diesel has a HUGE turbo that takes a little while to get going. I'm not sure if the lag off-the-line is turbo lag or pre-programmed throttle response to keep wheelspin from happening, though I suspect it's some of both.

Autos (in a gas engine) will try to hold on to the boost by not opening the wastegate entirely during a shift - dumping off all the boost. 

Aisin transmissions in general seem to back off power for a brief second for a smoother shift without a "thud" - my Camry and Volvo both did this, though I have never noticed this behavior in the GM automatics that just seem to slur shifts with the torque converter.


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## bigluke (Aug 18, 2013)

I think that if you drive slow for " x " miles there's some eco mode getting on from the driving habits, when you wot it couple of times I can see less lag on shifts and better turbo response.


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