throttle lift off lag

Pharmacist

i've noticed in my car ever since i got it that when i lift off the throttle, there is about half a second lag time during which the engine maintains current rpm before dropping off to idle. doesn't matter if the car is in gear or neutral or if srm is on or off. what causes this? is it the electric throttle being slow to respond?

DIGItonium

Try turning off SRM to see if it makes a difference. SRM holds revs in between shifts to anticipate gear changes.

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Pharmacist

like i said, i already tried that. its not srm. its not that the engine is held at a certain rpm, its more that there is around half a second lag time after i lift off the throttle before the engine revs down to idle.

AK370Z

Here's a great video that explains the upshift



BTW, this is NOT me . Some kid on youtube.

EDIT: I guess we posted at the same time. That's weird. Hopefully someone with the same issue will chime in.

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Daishi

lol neither of you 2 read what he said.. he already tried turning off SRM... mine doesnt have SRM and it does the same thing. Probably has to do partly with the extremely heavy stock flywheel

kenchan

or just a fuel map to burn off the last bit of fuel for emmissions control...

semtex

It's the heavy flywheel. More mass = more rotational inertia. That's why lightweight flywheels are a somewhat popular mod for Zs. The 350 was the same way. Nissan chose a heavy flywheel out of noise considerations.

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"There are no small accidents on this circuit." -- Ayrton Senna
316.8whp & 248 ft/lbs (Dyno Dynamics) | 319whp & 256 ft/lbs (DynoJet) (04/23/10)
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rufio11

Does Nissan use a DBW or is it a Cable? DBW lag sucks ballz

DIGItonium

Interesting... I never really recalled the 350Z holding revs in between shifts. Revs dropping slow wouldn't surprise me, but there has been some discussion in regards to the 370Z holding revs while shifting. It took awhile for me to get used to this behavior.

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vipor

sometimes, especially skipping a gear this leads to a "lurch"

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Pharmacist

wire. i agree it could be dbw lag. also the part about buring off the remaining fuel does seem to make sense. i highly doubt the heavy flywheel is the cause. a heavy flywheel would mean a slow rev down. what i notice is more that the engine rpm stays put without slowing down at all for about half a second or so, before beginning to slow down. the lag also seems to be independent of rpm. it's about the same duration whether at high or low rpm. if it was the flywheel, there would be more lag at high rpm and less at low rpm.

for those who say srm, no, actually the car doesn't even have to be in gear or even moving for this to happen. just try this. leave the car in neutral. push the throttle and hold the engine at a constant rpm, doesn't matter high or low. keep your eye on the tachometer needle, and immediately lift off completely. you should notice a small delay between the moment the throttle pedal is lifted and the moment the needle begins to drop.

also can someone with the automatic also try it just to see if it is indeed the flywheel or the electric throttle

Pharmacist

yeah, it's definitely noticeable if you upshift really quickly and immediately let out the clutch. the lag makes the engine maintain too many revs and can cause fast upshifts to be very harsh

semtex

Ooohhh....I think I misread your original post. You're not disengaging the clutch, are you? You're talking about a situation where you simply lift off the throttle but you're still in gear?

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"There are no small accidents on this circuit." -- Ayrton Senna
316.8whp & 248 ft/lbs (Dyno Dynamics) | 319whp & 256 ft/lbs (DynoJet) (04/23/10)
Stillen G3 CAI, CBE, Pulley / F.I. LTH / GTSpec Ladder Brace / Setrab Oil Cooler / UpRev-tuned by Forged Perf.

kdo2milger

circuitry lag

drive by wire

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semtex

That, and general lack of F-L-A-W-L-E-S-S-N-E-S-S.

__________________
"There are no small accidents on this circuit." -- Ayrton Senna
316.8whp & 248 ft/lbs (Dyno Dynamics) | 319whp & 256 ft/lbs (DynoJet) (04/23/10)
Stillen G3 CAI, CBE, Pulley / F.I. LTH / GTSpec Ladder Brace / Setrab Oil Cooler / UpRev-tuned by Forged Perf.