I have Turbo Lag...
I know a little about forced induction in general, but am not too familiar with modern Audi turbos (last one I learned on was an 87 5kcs qt). Nevertheless, I'll offer everything I can think of.
Is there anything in particular that makes you certain it's actually turbo lag? Modern factory turbos don't tend to have much turbo lag. When it feels like it's in "lag", does your boost guage confirm that not enough pressure is being built up? If that's the case, then my next question would be does the boost guage ever reflect that correct maximum pressure is being attained (most likely at wide open throttle and very high rpms)? If you are getting true turbo lag and the boost is not peaking at the correct value, then I suppose in theory the turbo itself could be at fault; however, that seems unlikely to me (Audi = bulletproof turbos). A little more likely would be an issue with the blow off valve, as it's directly responsible for controlling the amount of pressure that is allowed to build up in the intake manifold. I don't know how sophisticated the blow off valve is on your car, but if it's anything like our old 5000cs, it's just a spring-loaded valve. Could just be sticking a little bit or damaged so that it can't close fully. If that valve is letting pressure bleed off when it shouldn't, then it's bye-bye boost. The valve may be electronically controlled nowadays, though - I think that would help the ECU to cut back the boost to create certain fail-safe conditions. That brings me to...
Given these infernal, modern, computerized cars, though, I'd say the most likely cause for poor boost would be that the ECU is doing it on purpose. Too lean a mixture will melt aluminum engine internals, and turbocharging is just force-feeding air into the motor. If, for some reason, it can't deliver the fuel necessary to maintain a stoichiometric fuel/air ratio, then it would be in the engine's best interest for the ECU to cut down on the boost to keep the mixture at a safe level.
Even if your check engine light is not on, it would still be worth firing up VAG-COM to hook up to the car and check for any stored DTCs (I've found that some DTCs don't cause the check engine light to come on) and make sure the readiness codes are all high (set), and even run some diagnostics if necessary. It's some pretty useful software.
Yeah it may not be turbo lag. It I bet it is intentional on Audi's part. Also the car is an automatic.
Basically when I mash my foot on the accelerator, it feels like it takes forever for the car to even move, and then wham! Im off.
It's a real disconcerting feeling when you are pulling out into fast traffic from a stop.
Haha, it's mostly that I'm just good at making a little bit of information fill up lots of space so that it looks like I know more than I actually do. :-)
Has the car always had this behavior, or is it something that has recently developed? Also, is your check engine light on?
tested this out... If I go to pullout into traffic and slowly go and
then hit it to get going I too feel the drag... But when I sit at a
stop and and just floor it, I just get going with no drag???
Interesting....
Ah, I'm guessing it's not the 20 valve 1.8 turbo then? Perhaps it's the 2.7 liter bi-turbo? The 1.8 turbo is famous for it's lack of turbo lag.
Either way, I would be more inclined to chalk it up to the automatic transmission rather than the turbo. Time to upgrade to a manual. :-)
This is pure conjecture, but as far as what kre8ivea4 mentions, that may be due to taking off from a stop with wheels straight versus the wheels being cut at an angle. I believe you'll tend to find the same behavior in any front-wheel drive car that has a limited slip differential as well as some all-wheel drive vehicles which have some limited slip effect in the front diffs (like Audi Quattros).
Less differential slip means the tires fighting against each other more when the wheel is cut in one direction.
Ah, I'm guessing it's not the 20 valve 1.8 turbo then? Perhaps it's the 2.7 liter bi-turbo? The 1.8 turbo is famous for it's lack of turbo lag.
Either way, I would be more inclined to chalk it up to the automatic transmission rather than the turbo. Time to upgrade to a manual. :-)
Hehe, his wife Alyx can't drive a stick ;-)
Ah, that makes a little more sense now. You didn't strike me as an automatic transmission kind of guy. Haha.
So any idea what the next car is going to be? Another Audi? A3 with a 6 speed perhaps? S3 (are they even going to have those over here)? S4? S4 Avant is pretty damn hot (I like the wagons for some reason), and seems worth the extra cabbage.
Ah, I'm guessing it's not the 20 valve 1.8 turbo then? Perhaps it's the 2.7 liter bi-turbo? The 1.8 turbo is famous for it's lack of turbo lag.
Either way, I would be more inclined to chalk it up to the automatic transmission rather than the turbo. Time to upgrade to a manual. :-)
Hehe, his wife Alyx can't drive a stick ;-)
My wife is British - I guess I take her gear-stirring prowess for granted sometimes.
