Sorry for to make a problem/complainer thread but curious if anyone (RS5) has noticed

[CeepeRS]

a hesitation in the top gear during steady low RPM highway cruising? I randomly experience a gentle cutout of throttle in 8th gear. Steady light throttle below 2k RPM. Having nothing to do with a throttle delay upon requesting more or max power. This is specifically with gentle uniform throttle. For example, maintaining speed on a slight incline, or accelerating at say 1mph increments when the throttle/power cuts out and the car slows, and a few seconds later regains power. It happens when the engine is cold and warm. Can't say I have ever felt a cut out of power like this. No other issues with how the car performs outside of this gentle throttle hiccup. Anyone else?

[underboss24]

Does it almost feel like the car totally lost power for a split second? I had that happen once on the highway. I remember previously accelerating and than let go of the gas. I was cruising again and felt a jerk with the gas pedal down.m again. That jerk was short pause then acceleration kick. One of my car buddies thinks it’s the turbo boast building up.

[CeepeRS]

Does it almost feel like the car totally lost power for a split second? I had that happen once on the highway. I remember previously accelerating and than let go of the gas. I was cruising again and felt a jerk with the gas pedal down.m again. That jerk was short pause then acceleration kick. One of my car buddies thinks it’s the turbo boast building up.

Yes, what feels like a complete cut of throttle. It lasts for more than a split second for me. Maybe 2 seconds or more. Long enough where I can add slight throttle (without enabling a downshift, which happens normally) and notice nothing is happening until it comes back. It's can't be boost building because the amount of throttle shows no boost, and it's happening when holding steady, not accelerating. At least not acceleration in a manner which requires much if any boost. To me it's something like a throttle position sensor glitch since it's happening in the most subtle light throttle situations in the top gear only. If not that, it might have something to do with an error of the efficiency mode. I have that setting turned off.

[Omychron]

Sounds like the engine switching to Miller cycle. Feels like it cuts power for a fraction of a second.

What you are describing about the 2 second+ delay isn't normal, however. I had something similar accelerating from standstill. Damn dangerous on junctions. Tranny software update fixed that for me.

[CeepeRS]

Yes, it very much feels like a malfunction in relation to something like a miller cycle, if that is even confirmed to be on the 2.9 engine. If it was a more systemic problem it would happen under load at higher RPM's. I can only induce it with the most gentle steady throttle. However I did just get it to happen in manual mode in 6th gear slightly above 2k RPM, super light steady throttle and then cut out and loss of momentum for well over 2 seconds. I think it's happening more frequently now, which is a good thing for diagnosing. It's likely still too subtle and infrequent for a dealer to find. The standstill delay on hard throttle is a different issue, i think. That's found widely across VAG cars. The 2018 Golf R DSG for example has a rather long delay if flooring it from a stop. Widely reported and seemingly how it's designed or implemented. Not to doubt that they were able to improve that with a software update on your car.

[wwhan]

It appears that the Porsche derived Audi 2.9L engine also has Miller cycle: Brief Analysis: The 2017 Porsche Panamera’s 2.9L Turbo V6 Engine (http://youwheel.com/home/2016/07/05/brief-analysis-the-2017-porsche-panameras-2-9l-turbo-v6-engine/)

On the single turbo B9 3.0T, the Miller cycle AVS has a short intake valve duration of 130deg crank angle & limited lift of only 6mm for partial loads. Once the partial load is exceeded the lift increases.

[Omychron]

Both the 2.9 and 3.0 have a Miller cycle. They're the same engine.

[chi_marketing]

Both the 2.9 and 3.0 have a Miller cycle. They're the same engine.

There not the same engine...

[wwhan]

The B9 2.9L engine has a 86mm stroke, the 3.0L engine has 89mm stroke. The 2.9L engine "directly derives from the 3.0 TFSI"

https://audi-encounter.com/en/2Turbo-V6

"The 2.9 TFSI is derived from the likewise new 3.0 TFSI. Due to the higher internal forces, its stroke has been shortened by 3.0 millimeters to 86.0 millimeters. With the bore remaining unchanged, the displacement is now 2,894 cm3. The crankcase incorporates thin-wall cylinder liners made from grey cast iron, while the diameter of the crankshaft main bearings has been enlarged by two millimeters."

https://www.audi-mediacenter.com/en/techday-on-combustion-engine-technology-8738/efficiency-and-driving-pleasure-innovative-v-engines-at-audi-8748

[Omychron]

There not the same engine...Yes, they are. Slightly lower stroke on the 2.9, upgraded intercooler and biturbo upgrade. That's it. So yes, they both have a Miller cycle.

Edit: Didn't know about the crankshaft upgrade. Interesting! Thanks for the info.

[heymoe]

I don't think you understand what the word "same" means. If you say: "They are the same except for ...." then they are not the same. :) hehe

The 2.9 is similar to / based off of the 3.0 would be more accurate. I know I know, it's being nitpicky.

[Omychron]

I don't think you understand what the word "same" means. If you say: "They are the same except for ...." then they are not the same. :) hehe

The 2.9 is similar to / based off of the 3.0 would be more accurate. I know I know, it's being nitpicky.So when I upgrade my turbo or intercooler I have a different engine? They are "the same".
Audi gives both engine the same basic engine type (EA839), but different engine codes to distinguish between the accessories attached.

Makes sense too, why develop completely new engines if you can use one type to power multiple models?

[heymoe]

So when I upgrade my turbo or intercooler I have a different engine? They are "the same".
Audi gives both engine the same basic engine type (EA839), but different engine codes to distinguish between the accessories attached.

Makes sense too, why develop completely new engines if you can use one type to power multiple models?

The core of the both engines have slight changes such as you can't use the crankshaft / bearing from the 3.0 in the 2.9 or vise versa for example without modifications. It's a slight change yes but a change none the less thus not the same. Sure you can change things bolted to the core such as turbos and ICs to get different performances out of the same core engine but the core is the core unless you start modifying the core like boring out the cylinders and changing out pistons for the larger size at which point all cards are off the table as things being the same.

Once again. "Same" is defined as: identical; not different.

Both engine cores can share 99% of the parts, technology, etc.. to make them but that still doesn't make them the "same", just very very very similar.

Audi even calls the 2.9 a variant which means a form or version of something that differs in some respect from other forms of the same thing or from a standard. (same != variant)

Look, I get what you mean / are saying and like I said I'm just being nitpicky about the terms being use.

[c99]

So when I upgrade my turbo or intercooler I have a different engine? They are "the same".
Audi gives both engine the same basic engine type (EA839), but different engine codes to distinguish between the accessories attached.

Makes sense too, why develop completely new engines if you can use one type to power multiple models?

When You upgrade your turbo and intercooler you will have a different engine, but not 2.9TFSI DECA with 331 kW [;)]

The engine block is slightly different, different cooling, camshafts, pistons, crankshafts, connecting rods, exhaust, ECU, etc., they are brothers, but not twins.

So many people thinks, that RSx is just small upgrade of Sx, but truth is, Sx is just small upgrade of Ax Sline. I had had A5 and S5 too, so I know what I am talking about. [:)]

[wwhan]

The short block is different between the 2.9L and 3.0L (2mm larger main bearing size and different crankshaft). There may be other differences.

Another example where the engines are similar and not same is the C7 4.0T short block, which is different between the S6/S7 and the RS6/RS7 (2mm larger main bearing size, different crankshaft, different pistons, additional T6 heat treated block & different cams).

[mnotae]

a hesitation in the top gear during steady low RPM highway cruising?

Getting back to the original discussion before the hijack, Did you ever find a solution to the inconsistent throttle? I'm having the same issue...same car.

[303 Spartan]

Oh weird, one more thread derailed thanks to an S5 owner making bogus statements in yet another futile attempt to downplay the differences between the S5 and RS5. The purchase justification cycle is endless in this sub-forum... [rolleyes]

[activeseven]

Oh weird, one more thread derailed thanks to an S5 owner making bogus statements in yet another futile attempt to downplay the differences between the S5 and RS5. The purchase justification cycle is endless in this sub-forum... [rolleyes]

This x 1000

[mnotae]

Getting back to the original discussion before the hijack, Did you ever find a solution to the inconsistent throttle? I'm having the same issue...same car.

SUCCESS!!! After a lot of sleuthing, I figured out that the throttle issue was actually a brake pump issue caused by the Adaptive Cruise Control System. If you leave it on (stalk not pushed Fully towards the dash), it somehow engages the brakes, etc....I mostly felt it in city driving. Seems like they still have a glitch in the system as that shouldn’t happen when a speed isn’t set, etc., but good to have finally figured out what has been going on.

[SixShifter]

I notice what the OP describes, but only in low gears about a mile from home. Momentary cut-out, but happens only once and lasts for maybe 1-2 seconds. 2019 RS5 coupe.

[hilltop804]

SUCCESS!!! After a lot of sleuthing, I figured out that the throttle issue was actually a brake pump issue caused by the Adaptive Cruise Control System. If you leave it on (stalk not pushed Fully towards the dash), it somehow engages the brakes, etc....I mostly felt it in city driving. Seems like they still have a glitch in the system as that shouldn’t happen when a speed isn’t set, etc., but good to have finally figured out what has been going on.

This is so obscure, how did you figure it out?

I guess the solution is to cut the adaptive cruise completely off when not using it. My car does the power cut out as well.

[wwhan]

This is so obscure, how did you figure it out?

I guess the solution is to cut the adaptive cruise completely off when not using it. My car does the power cut out as well.

I have not noticed it yet, but I use the adaptive cruise control a lot on expressways and in school zones to limit my speed (closer to the speed limit).

[Bagy]

Hi everyone :)
I have the same issue on my car. The only difference is that i don't have adaptive cruise control.

Did somebody find anything else what could cause the issue?

Thanks

[dal59]

SUCCESS!!! After a lot of sleuthing, I figured out that the throttle issue was actually a brake pump issue caused by the Adaptive Cruise Control System. If you leave it on (stalk not pushed Fully towards the dash), it somehow engages the brakes, etc....I mostly felt it in city driving. Seems like they still have a glitch in the system as that shouldn’t happen when a speed isn’t set, etc., but good to have finally figured out what has been going on.

Interesting. I hope that "fix" works for everyone. I always keep my cruise control in the off position (fully forward) as I never use it. However, if that were not the cause and it was a throttle sensor, would you think that would throw a code the tech would be able to see?

[Dan99]

a hesitation in the top gear during steady low RPM highway cruising? I randomly experience a gentle cutout of throttle in 8th gear. Steady light throttle below 2k RPM. Having nothing to do with a throttle delay upon requesting more or max power. This is specifically with gentle uniform throttle. For example, maintaining speed on a slight incline, or accelerating at say 1mph increments when the throttle/power cuts out and the car slows, and a few seconds later regains power. It happens when the engine is cold and warm. Can't say I have ever felt a cut out of power like this. No other issues with how the car performs outside of this gentle throttle hiccup. Anyone else?

If you are below 2k rpm, put it in Sport so you are in 7th. It won't hurt your mileage if you don't change how you drive.

[MAIDANG]

SUCCESS!!! After a lot of sleuthing, I figured out that the throttle issue was actually a brake pump issue caused by the Adaptive Cruise Control System. If you leave it on (stalk not pushed Fully towards the dash), it somehow engages the brakes, etc....I mostly felt it in city driving. Seems like they still have a glitch in the system as that shouldn’t happen when a speed isn’t set, etc., but good to have finally figured out what has been going on.

I experienced this exact power loss while under cruise control. I was going 100km/h. Speedo drops 1km/h and go back in a second. This happens every a few minutes. I bought my car for 2 weeks second handed, and I'm going to the dealer to see if they have encountered this issue before or if they want to fix this.

[ywang98]

This was more apparent in my 2018 S4. It annoyed me a lot.
In my RS5, I've recently noticed it as well, but only very slightly.
Will try the cruise control stalk to totally off.

[RUNSGR8]

I have this issue as well with my 2018 RS5 coupe. I don't have adaptive cruise control but I have noticed that it only tends to happen in wet or windy conditions. It's very subtle and easy-ish to miss if you're not paying attention. I'll be cruising at 75-80 mph in 8th gear and the car will feel like it started to coast; 2-3 seconds later it will gently kick the power back in and continue along as if nothing happened. I only have this happening at highway speeds and never at low speeds.

I haven't experienced any major issues with this weird behavior, but it might be related to the sport diff or traction control system since it only seems to happen in wet/windy conditions.

[Dan99]

I have this issue as well with my 2018 RS5 coupe. I don't have adaptive cruise control but I have noticed that it only tends to happen in wet or windy conditions. It's very subtle and easy-ish to miss if you're not paying attention. I'll be cruising at 75-80 mph in 8th gear and the car will feel like it started to coast; 2-3 seconds later it will gently kick the power back in and continue along as if nothing happened. I only have this happening at highway speeds and never at low speeds.

I haven't experienced any major issues with this weird behavior, but it might be related to the sport diff or traction control system since it only seems to happen in wet/windy conditions.

I'm on my 3rd Audi with the Sport Differential and have not experienced this. You will get some coasting in cruise if you are on a slight downgrade, perhaps this is what you are feeling...?

[MikeRS5]

Hi all, I had to change the front pads (carbon ceramics) on my MY18 B9 RS5 and right after I started to have this issue. Anyone were doing something with the brakes before your issue started? Maybe reset in the settings after new pad install might have triggered something ..

However I'm on the stage1 ECU tune (TCU not tuned). I got adaptive CC. I switched to dynamic mode and I was still able to reproduce the issue in low rpm (1500-3000 + slow acceleration). Boost creep/leak or sensors (ACC / Audi Pre-sense) stepping in..

PS: I was little worried that turbos bearing or some other component might worn out as I had high pressure pump failure about 1500 km before and a little amount of gasoline was mixing with the oil (I caught it prematurely but it still might be enough to cause damage to other components by not lubing them properly). I will be more than glad to hear that its just some tranny TCU or ACC glitch.

Anyone had luck with their car yet?

Thanks,
Michal