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Discussion Starter #1
I know it is a design function of the diverter valve, but after driving N/A cars all my (albeit short) life, I don't think I like how long it takes the engine RPM to come down when I let off the throttle to shift.

It seems that if I accelerate fairly hard and beyond 4,000 RPM, there is about a second after I let off the throttle that the RPM "hangs" or even goes up a little more, and then slowly goes back down.

I have always driven a 5-spd to try and match engine speed to the transmission, and if I do this in my Passat, there are like three to four second delays between gears. If I do accelearte hard and just shift as fast as possible, the transmission has to grab hard and "slow down" the engine to match the next gear's speed.

I'm sorry if I am not saying this right, but is this what I should just expect with a turbocharged car? I feel like I could be putting all kinds of extra wear on my clutch if I just shift and not try to match engine/tranny speeds.

Thoughts? What are your driving/shifting styles?
 

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I notice my passat does this too.

My old 95 accord with a prelude vtec motor swap never did this, it would own my passat from acceleration to top speed.
 

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I just noticed this phenomenon after some recent maintenance work. Not sure why I didn't notice it before. Even if I give it light throttle and let off, say creeping up to a stop sign in traffic, it'll hang like you said for a couple seconds.

I initially thought it was because the engine was spinning more freely or something (new timing belt and everything associated with it).

For comparison, the V6 in my mom's Audi A6 spins very freely if you rev it and will hold RPMs for a hot second before slowly falling back down. This is in neutral or park, mind you. On the other hand, in my dad's Porsche 911 the tach needle drops like a stone in a pond when you let off the throttle.

I drive rather sedately but I use the transmission a lot for speed control, downshifting to brake and so forth. I always blip the throttle to match revs when doing so, but I'm working my clutch twice as much.
 

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It's not the turbochager that's causing this, but a function of the drive-by-wire. It's programmed for the revs to drop slowly when releasing the throttle for lower emissions. It also isn't just VWs that are like this. Most any car with DBW will behave like this.
 

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i believe, as AA said, that our heavy flywheels are the biggest contributors to this. i think they are somewhere in the hood of 30lbs. that is quite a lot of momentum. lightened flywheel :thumbup:
 

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This is 90% due to the weight of our flywheel. The other 10% is probably due to the relatively heavy pistons and other moving parts, compared to the fly-weight (low-torque) rev-happy Japanese engine philosophy.

It's definitely a little annoying...Out-of-gear wait wait wait wait wait Into-gear.
 

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Its a function of emissions. Do it when the engine is cold, and its 5 times worse. Although the heavy flywheel prolly doesn't help (yes, I hit 5 psi boost screwin' around in neutral :lol: ).
 

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Discussion Starter #12
So a new clutch/lightened flywheel would help aleviate the problem (but probably introduce other problems like chatter).

Thanks for the info everyone!
 

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I have a cable-throttle AEB 1.8t and I feel the lag like the rest of you. I doubt it's the computer doing it... unless it's doing it by some mechanism unknown...
 

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Why would it be a fuction of emissions?? There is no reason to keep the revvs higher (higher revs = higher mass flow through engine=higher emissions on a transient cycle). And it can't be a fuction of trying to "warm-up" the catalyst because at zero throttle the engine cuts fuel (one of the biggest reasons fuel injection gives better fuel economy than carburetors). As far as during an acceleration the additional mass requires additional fuel=worse emissions and fuel economy. The only other factor left is driveability, so the added flywheel mass must help the average driver (read not most of us!! :D ) feel more at home in the car, as it will lessen "jerk" (change in acceleration/unit time) and make a 1000-2000 rpm clutch engagement from a stop easier (flywheel rotation inertia gets transfered into foward inertia, so you are less likely to stall the engine or have jerky starts).
 

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The engine will run rich for a cycle or two before computer has a chance to change fuel map prolly on the dbw= slow(er) rev drop built in, mine drops pretty fast w/o dbw.
 
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