Hi,
I can’t find topic talking about the following issue.
After installing the last version of the FBW A320nx, taxiing goes crazy.
Just after release parking brake, the plane start to taxiing by itself whereas throttle is on idlle position.
If I don’t use my break to decelerate, the plane reach easily 30 kts…
Does someone have an idea to fix that issue ?
Make sure you’re on modern flight model, not legacy.
In real live the a320 works like this! The idle engine can move aircraft easy.
He talks about it here…it’s a real thing.
Yes, use the brakes and/or reverse thrust 
I’m glad you posted this because I also experienced the same issue and everyone jumped onto me about how this is “normal.”
Technically speaking, it is normal and it’s not really a bug or issue. IRL, aircraft have a tendency to begin rolling a little once the brakes are released without requiring any thrust input. Watch any video or simply take noticed the next time you fly. However, notice how I said “a little.” To keep the momentum going, a little bit of thrust is required, especially if taxiing upslope, or when making turns. Also, if you’re on a long taxi, you might want to taxi a bit faster than normal, thus requiring some degree of thrust input.
Now, I had used the default A320 since launch until it broke in the USA update (AP bug). I did think that the default A320 was a little underpowered on the ground and it felt almost like it was stuck in “quicksand.” So, I gave the FBW mod a try and the first thing I noticed was the taxiing issue you pointed out. With brakes released and taxiing at idle on a flat surface, I quickly reached about 30-40 knots which is way too fast for taxiing. I kept having to hit the brakes and I always felt like a “runaway train.”
So in conclusion, I think the FBW mod tries to simulate real life more than the default in terms of taxiing. However, the mod seems to simulate this a bit more aggressively than IRL. I wasn’t really a fan of it and it took away from the mods realism personally.
A tip someone suggested to me was to taxi with higher payload or with one engine, but neither of those seemed to make any difference for me.
the HOLD function works fine now? do you know?
I should add that it may help to have a better system for braking. Having brake pedals might make it feel more realistic as you can add different amounts of brake pressure/input. As for me with my joystick and brake “trigger” I only have two braking abilities, all or none, so this doesn’t help.
No. Once a jet starts accelerating during taxiing, it usually continues to accelerate on its own.
That’s correct. Same IRL and on many jets you have to watch the brake temps closely during taxiing to avoid arriving at the departure runway with hot brakes!
I haven’t tried the modded A320, but if there’s no difference between two engine and single engine taxi, then there’s something wrong.
This is a normal thing in the real plane. They fixed the issue where the plane would decelerate and take tons of thrust to get moving.
A320 Sim Pilot on YouTube said the behavior is realistic and that you generally keep accelerating without engine power (and need to brake).
See 14:45 of the video someone posted above ^
True, but typically if it’s taxiing downslope. Trust me, I’ve flown a lot and I watch tons of YouTube videos, and I’ve heard thrust increases quite a bit.
Good point and exactly why I didn’t like it. I should’nt be fainting that much speed quickly taxiing with engines idle. It felt to me like the opposite of the default, too much power.
We have been around the forums long enough to benefit from many of your posts this past year. I suggest you take a look at the A320NX mod. Simply stunning the amount of systems that have been improved. We look forward to reading your comments.
So I watched the video and I realize it’s a normal thing in aircraft, but something about it in the mod just seems a bit off. Way back after launch, I brought up how I wished it taxied without requiring so much power. I was reaching almost 30-40 knots at idle if I didn’t repeatedly keep hitting the brakes the whole time. It felt like I had way too much momentum, where as the default was the complete opposites. Also, I shouldn’t be accelerating when I’m taxiing upslope, so explain that one.
I think I remember somewhere that the FBW team couldn’t increase the idle thrust level to make the aircraft rolling.
So instead, they reduce the “friction” coming from the wheels on the tarmac and make it slightly negative. That way, even on idle thrust level, the game “simulates” a negative friction on the wheels and make it start rolling.
Of course, with negative friction means the plane will keep on rolling indefinitely until you apply some brakes.
However technically, physics dictate that even when the aircraft is on idle thrust and enough to keep it rolling. There has to be a point of equilibrium where the drag from the air resistance plus the friction from the tarmac will be equal to the idle thrust given by the engines. Thus making the aircraft reach a stable ground speed without accelerating nor decelerating.
I need to test this theory though, on a long runway, and let the aircraft rolls itself see how fast it can reach.
No downslope required.
I’m not judging by watching youtube videos, only from my own RW experience.
If there’s a thrust increase, it’s just to reach the ‘target’ taxi speed faster.
Thanx for you kind words 
, but I haven’t used a single mod since its release and until MSFS is in a more finished state, I’d like to keep it that way.
I think it depends on your take-off and/or landing weight. If you start light (25% or less) for a short trip you will definately start to roll when releasing the brakes, even more so after landing.
Depending on your gross weight I’d consider it normal for the bus to start rolling with idle thrust. Or do you mean it follows the actual taxi route by itself?
To me, that’s definitely what it seems like they did. I think on the default, the friction is set too high, just the opposite. That’s probably why the plane continues to gain speed until it’s too high, which is unrealistic.
I Think of it like the good ole fidget spinners. Some had too much friction and would stop spinning quickly while the better ones wold keep spinning for a while. Similar enough concept here with the mod.
But I tested this solution and put nearly max payload on and it still rolled, no difference.
Also, I should add that it’s less than ideal to weigh down my plane to max payload if I’m indeed flying a short haul flight. Yes, I know that I can remove the weight in the top menu bar in flight so that I’m not overweight landing, but then I have the same taxiing problem on the ground at the destination when I’m back down to near empty payload.