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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Lag from dead stop



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      06-18-2013, 04:00 PM   #23
Jeff@TopGearSolutions
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The so called lag is just the drive by wire system. It's sort of a safety and comfort mechanism. If the throttle is too abrupt at the onset of depressing it would make the car jumpy and jerky.

Tunes can help a little but it's just the nature of a car with a drive by wire.

Last edited by Jeff@TopGearSolutions; 06-18-2013 at 04:07 PM.
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      06-18-2013, 05:54 PM   #24
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I find pushing the pedal in gradually instead of stomping it is much better personally
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      06-18-2013, 10:35 PM   #25
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I get that there's a long path to get there, but I've driven plenty of turbo cars w/ electronic throttle and they don't have the same issue. Plus it's not that it takes a long time for the air to move, it's that nothing happens and then it hits. Turbos aren't spooling so it shouldn't respond like that. And my previous IS350 was DI and it didn't have the same lag. There was a tiny lag in throttle, but after the ECU adapted, it was gone. Nothing like the 335. You'd think that with it being electronic, they could compensate for the lag.

Oh well, nothing to be done anyways. Just something to live with.

Quote:
Originally Posted by E90Company View Post
Numerous factors. Bigggest factor of your specific comparison would be turbo vs NA. Taking turbo lag out of the equation for a moment, on the N54 air needs to get sucked in through small inlet tubes (2), pass through the compressor wheel, join the seperate air channels in through an intercooler biggest restriction right here), then up through a charge pipe that have diverter valves open at idle/until the TB opens and creates pressure in the intake manifold for the DV's to close. All of this signifigantly reduces throttle response as you would be used to in your comparo. All the NA motor has to do is open the TB and air goes straight into the combustion chamber. Adding turbo lag back into the equation, it makes it even worse.

Also, head design (N54's head flows very poor in comparison to say the E46 M3's S54), intake manifold design, and obviously electronic throttle tuning plays an important roll in throttle response.

This car is a DI motor (I don't think that Infinity motor is) so carbon caked on top of the intake valves will add to the delay you feel, among gearing differences as you mentioned (That's more how fast power can be put to the ground however)
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      06-18-2013, 11:52 PM   #26
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Quote:
Originally Posted by DuDai View Post
Pretty sure the lag these posters are referring to is just the DriveBYWire system. They're known for having a lag. Although i find it tends to make for extremely smooth take off if you don't romp on the gas. I've driven several Drive By Wire systems, a bunch of BMW's, Cadillac CTS, and my work truck 2010 GMC 2500HD, and they all experience this slight lag upon take off. It goes away if you really step on it, but if you just do a normal take off its a noticeable lag but makes for extremely smooth and gentle take off.

Call me crazy, but i thought i once read that was the purpose of this lag, for a smooth gradual take off. The computer for some reason puts the throttle on gradual. I know that some tunes remove this "feature" so its back to the normal way.

I've had my car a about 6 weeks and had trouble on take off - thought I just had to get use to the car. In the last week or so, the car got use to me. Pulling away from a stop sign is much smoother. My old 330 had drive-by-wire that adapted to your driving style and got slower and slower, but you could reset it by having the key in accessory start (not turning over the engine) and then turning the key off and turning the car back on. Does a 335 have a procedure like that for wiping the "adapts to your driving style" memory? I'm thinking not - I sure haven't found anything on it here. There are times when a smooth start is good but I want it only when I want it.

edit> This is on an auto but it shouldn't make a difference if it is a throttle issue.

Last edited by Colo M/Sport; 06-19-2013 at 11:18 AM.
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      06-19-2013, 09:46 AM   #27
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I don't notice much if any drive-by-wire lag as I notice what I think is torque management when I floor it in 1st gear (6AT). It's as if I'm getting 60% throttle in first with gas pedal floored. Then 2nd gear and thereafter feels like WOT.

Anyone else know what I'm referring to? Does a tune fix this (1st gear "torque management?")

DTC fully off btw.
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      06-27-2013, 01:02 PM   #28
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Throttle lag fix kinda

Well once the JB4 adapted, the lag came back but if I reset it back to learning, it improves for awhile. I did find one thing that has helped a tremendous amount and would indicate it is a control problem, not lag. When I come to a stop light, I flip the shift paddle back and it goes to M2. It virtually fixes the problem and makes getting into traffic much easier with virtually no lag and you can use as much throttle as you like. You can use M1 but it is more abrupt than M2.

My SL600 was the same way because it starts from a stop between 1st and 2nd gears (huh?). If you selected first or second manually it was much better.

Please post your experience with this. TIA

Last edited by lconn; 06-27-2013 at 01:03 PM. Reason: additional info
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      06-27-2013, 02:35 PM   #29
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Quote:
Originally Posted by e90inAZ View Post
I don't notice much if any drive-by-wire lag as I notice what I think is torque management when I floor it in 1st gear (6AT). It's as if I'm getting 60% throttle in first with gas pedal floored. Then 2nd gear and thereafter feels like WOT.

Anyone else know what I'm referring to? Does a tune fix this (1st gear "torque management?")

DTC fully off btw.
Is this stock? Some tunes provide torque management kind of feature and lets you limit boost in lower gears. Is it maybe not building enough load request in first to fully spin up the turbos?
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      06-27-2013, 05:56 PM   #30
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Quote:
Originally Posted by deathbunny View Post
Is this stock? Some tunes provide torque management kind of feature and lets you limit boost in lower gears. Is it maybe not building enough load request in first to fully spin up the turbos?
Yes 100% stock.

Is this normal?

I've felt it on other newer cars. They tune the ecu from the factory to limit WOT in 1st gear to a) not let you break the tires lose for safety reasons and b) save the drivetrain so they don't pay out large sums of money for warranty repairs.
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      06-27-2013, 07:23 PM   #31
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Not sure I haven't heard of stock cars doing that but defiantly not saying they don't. I did experience the same thing you are describing on my Stage3 Audi 1.8T. First gear would never build as much boost as the other gears. I dont know if it was programed like that I just always assumed it was geared to low to need all of the boost based on the load targeting system.
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      07-29-2013, 01:02 PM   #32
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Maybe this thread can help you out http://www.e90post.com/forums/showthread.php?t=791297
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      07-29-2013, 10:02 PM   #33
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Had a new 535i loaner while the 335 was in the shop. It does NOT have the same lag as 335. Part of that may be the n54 vs n55 but it feels like the drive by wire.

I bought the car as a CPO with 35k on it and it has done it since day one. If it can do it properly in M2, it's software. The nice thing about putting it in M3 with the paddles (other than they finally have a use) is once you get going the tranny automatically goes back to regular drive.
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      07-29-2013, 10:11 PM   #34
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I've heard folks talk about turbo lag, but I can say I don't think I've ever noticed it. I have an MT, would that be why? ???
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