Hi Guys. I just wanted to post my experiences with this same issue. I too had similar issues with my G920 wheel. It was hard to control the car, always seem to lose control around simplest corner, and lots of snaking and overcompensation etc.
My wife also plays Forza with me. We played through the whole of Forza Horizon 2 with the G920 and it was fine at default settings (except for dialling down max lock to 600 from 900).
We tried Forza 5 and the wheel was absolutely pants. Was better on Forza 6 and the Forza 7 demos but not bought those games as we prefer Horizon. We missed Horizon 3 as didn’t fancy Australia, prefer more green trees etc as in horizon 2 and 4.
Well after 10 mins in Forza Horizon 4 my wife was ready to chuck the whole wheel out of the window I think. I got the game on game pass so was a bit miffed when the wheel didn’t work properly but hey ho, I thought well it hasn’t cost me anything, maybe they’ll fix it for the next Horizon game…
I tried some of the settings that someone (thankyou) above mentioned as in messing with understeer/ oversteer, FFB and vibration. This made it a bit better, but still felt off. Was going to write if off.
But then I also saw somebody mentioned that there might be display lag on my TV causing an issue. I have changed our TV since Horizon 2. We used to have a 15 year old Pioneer plasma TV 720P, no smart features and all picture enhancements disabled.
My new TV is a Samsung 4K HDR TV. Its not a super expensive one, it was £400 used from Ebay. I had another look at this tonight and I did notice something in the in car view/ dash view. When I moved the steering wheel, there was a noticeable delay before the wheel on the TV moved. It was quite a delay and the car also would not move for a bit after steering wheel input. We didn’t notice on the outside car view which is the view my wife usually uses but I prefer the in car view.
Well I hunted through the TV settings and sure enough, there is a “game mode”. I have never used game mode for anything and we’ve played several other games (Gears 4, Titanfall 2 etc) since buying the TV with it turned off and not really noticed any problems.
BUT…this seems to have fixed all our problems. The wheel on the TV now turns almost instantly. You can also look for this by simply pressing the pause/map button. Before, there was a delay before the map came up. I thought this was normal. But it isn’t, the map should appear pretty much straight away. I went back to the default steering wheel settings (but still dialled down to 600 as in FH2). And it is SO MUCH BETTER. My wife is driving now, she picked up on the difference straight away so if she can notice it, it must be different.
I know this won’t fix everyone’s issue as we might be having different issues. My G920 is on the 2016 firmware and I’ve done the brake mod, its been like this since we played FH2 on it. This has totally fixed my issues though and I feel comfortable now playing on default steering wheel settings. We’re not the best drivers anyway so if you are pro you might be more sensitive to the wheel than we are but to just play through the single player game and have some fun, we can do this now without crashing at every corner or coming last in every race because we had to drive around at 30mph to stay on the road!!! I just drove around aimlessly for 30 mins and it was great, overtaking cars, getting between cars at over 100mph. Couldn’t even go round corners properly before and the snaking has all gone. I guess because we had lag, the game is constantly behind what we’re doing, leading to overcompensation and constant steering corrections because the car doesn’t react for a while.
Anyway, I’m not suggesting this is a fix or the cause but its worked for us.