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Turbo Lag is not a buzz word - Tip Lag is not Turbo Lag: Even more tiresome thoughts... =)

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Old 10-09-2002, 10:52 AM
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Default Turbo Lag is not a buzz word - Tip Lag is not Turbo Lag: Even more tiresome thoughts... =)

Turbo Lag -- By the laws of this universe, pressure in the intake manifold must be built up over time, and can not be instantaneously raised to a fix point above ambient air pressure. This time delay, between no boost and max boost, is Turbo Lag. For the period to elapse, engine RPMs must build, exhaust gasses generated, and the turbos spooled.

Tip Lag -- I've heard several different things referred to as "Tip Lag".

a) Car at stop, brakes applied. Brake lifted and Gas quickly applied. Car doesn't go. --> This seems to be software related. Accellerator pedal position does not immediately correlate to fuel delivered. The earliest of allroad reviews claimed the throttle was too touchy from a stop in offroad situations. Audi has apparently addressed that, to an extreme.

b) Car rolling slowly. Gas applied. Car takes time to build rpms, boost, etc... --> This isn't an inherant design problem with either the transmission or the turbos. Any car will bog if it's accellerating from too high a gear, and too low a position on the Tach. Just use that tip button.

c) Car doesn't accellerate as fast as a 6-spd. --> That's the torque converter, which necessarily loses some torque as heat - while introducing a delay in the torque delivery... can't do anything about that, short of buying a manual. ;-)
Old 10-09-2002, 11:17 AM
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Default your a) is what I notice, and I believe it's intentionally programmed into the chip(s).

...and p.s., my 1999 Saab 9-5 V-6 with asymmetrical light turbo had NO discernible turbo lag. Of course there must have been a lag (see physics lessons above and below) but all those steps took place within the envelope of perception.
Old 10-09-2002, 11:37 AM
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Default Big Question - if throttle has been intentionally "desensitized"...

then how can we change that? Would it be a mechanical change or can we do it via software? For if your (a)is really true, we should be able to correct it!
Old 10-09-2002, 12:12 PM
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Is buying a manual the only answer? Why did my previous Turbo Volvo show no lag?? Just asking.
Old 10-09-2002, 01:37 PM
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Default I find turbo lag quite short, and not really a problem...

It's TIP lag that's the problem, mostly under full or nearly full throttle, from a standstill or slowly moving. The dealer says my ar has the latest TCM.
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