CH 14

I have a new 2017 S4 which has awful acceleration lag especially noticeable when pulling away from a standing start when you need to accelerate reasonably fast into moving traffic on roundabouts, junctions etc. to the point I believe it could be dangerous, so in turn you have to wait for a larger than normal gap to pull out in, which then annoys those waiting behind you. I cannot make my mind up if it is throttle lag, gearbox lag or clutch lag or a combination.(I would not attribute the issue to turbo lag) It has been back to the dealer twice now re this The dealer acknowledges that there is a lag, but does not know what to do about it other than now saying this is normal, they suggested contact Audi customer service each time who in turn said take it back to the dealer.The dealer then said call Audi customer service again and now report it as gearbox lag which I tried to do but they are not responding to calls or emails. I have since been in a new S5 which has similar engines and gearbox's and also appears to have a similar lag issue.Before this car I owned a 2014 B8 S4 which was really good with no issues at all so I am totally disappointed with this car.
Has anyone else noticed this issue with B9 platform Audi's.

markcincinnati

There is no "B9" 2017 S4 in the US.

It is, of course, possible for there to be turbo lag in a turbo charged car -- unless the turbo is helped via an electric motor that is designed to keep the turbo at near full boil.

You say you have no turbo lag (apparently). If that is, indeed, the case, what is left that could contribute to lag?

Of course the answer would appear to be the automatic transmission. Not sure what or why you mention "clutch" lag. The DSG transmission is not offered in the S4, only the "conventional" 8-spd auto is used in the S4.

All of the above assumes that this post pertains to the North American (B9) 2018 S4.

If we eliminate the engine AND the transmission -- what remains?

Assuming you have no "hardware" pieces that can be identified as the culprit, what remains is software or human causation.

The human, if that is the case would be, of course, the driver. I find it somewhat to a lot difficult to imagine what the driver is doing that could cause lag, other than not pressing on the accelerator pedal sufficient to effectuate the acceleration you want.

Let's put human error on the shelf for now.

What remains? Software.

It is, of course, possible for any "computer" to need to have its "operating" system reloaded. We've all, probably, had our PC's develop "issues" that this, that and the other "fix" doesn't rectify.

So, what do we do? We reboot and then "remove and replace" Windows, Office and google and chrome. This approach has proven successful in SSD and spinning disk PC's.

There is a computer with millions of lines of code somewhere inside your S4. It can be overwritten with a "new" version of the S4's "operating" system -- the one that literally is the brain of the car.

This approach, once you eliminate hardware (even including tire pressure) and human error, is all that remains. Service departments are trained to plug a diagnostic computer program into the on board computer to read "fault codes" -- then after reading those codes, the remedy is to: Repair or replace or adjust. Rarely are there parts that can be repaired. Parts, currently, are typically simply replaced. Adjustments -- via software -- are also part of the remedies available, too.

So, if, indeed ALL hardware is rendering ZERO errors codes AND then the software is overwritten with a refreshed version of the Audi OS, all that remains is for you, the human, to submit yourself to a battery of tests to determine what fault codes you throw out. Then, either parts, your parts, will have to be trained, "repaired" or amputated and replaced with prosthetic limbs, etc.

I must say, and I am willing to apologize, if I am wrong, that this post seems suspicious to me. Too many "markers" such as calling the car a 2017 S4 -- considering that audiworld is dominated by North American participants and that we all know there is no North American 2017 S4 (B9).

superswiss

A turbo engine has lag. They've been getting better by putting in smaller turbos and the current generations put the turbos in the Vee to shorten the exhaust paths, but at the end of the day the turbo still has to spool up first before the engine develops full torque and power.

The transmission programming and throttle maps will introduce additional lag to minimize fuel consumption. Unfortunately, everything car manufacturers do now is about efficiency.

What you describe, does this happen with the transmission in D? What about putting the transmission in S?

plat27265

+1. If you are in Comfort or Automatic or Efficiency mode, the throttle and transmission response characteristics will be a bit slower compared to the quicker response when in Dynamic or Sport mode.

CH 14

The lag occurs in all modes, no matter which one you select and which options in the individual mode. This is a 3litre engine with 354 hp even if the turbo was not working it should still have enough power to pull off the line reasonably quick.

plat27265

Is the car broken in? What's the mileage on it?

Talbot

Accelerator pedal position sensor.

CH 14

Only 730 miles

jjsC6

The one I test drove did the same thing. I've owned a number of trubo cars and I understand the difference between turbo lags and other types of lag. What I felt was turbo lag ONLY from a dead stop. Turbos do not make boost if there is no load on the engine. As mentioned above, there are ways to diminish it. And sometimes today it's just so minor you don't even notice it. I had a twin turbo BMW 550. It truly amazed me that from a dead stop any lag was imperceptible.

The best way around it from a stop is to brake torque it a little to spool up the turbos under
load.

plat27265

+1. I agree that any turbo car except for twins where the smaller turbo is electric will always have a degree of lag. My dad used to own a 1996 Mitsubishi Eclipse Turbo and if you want to experience turbo lag that one had it and it was awful. But, once in boost, it is a hoot! Turbo technology nowadays have almost eliminated lag. My 2011 VW GTI had a teeny tiny bit of lag. It was there especially in certain conditions like if you are starting from a dead stop at an incline. But, not noticeable enough that you'd count 1001, 1002...

To the OP, I recommend test driving another B9 S4 and comparing the response of that car to your and see if they're the same. If not, then your car might need a visit to your Audi service center.