This has happened to me a few times now. I've been running 10-lap races against the AI at Aston Historic, and although I'm not 100% sure, it seems that every time I get into a bit of body action with the AI (nothing too violent), and perhaps run off course once or twice (hey I'm still learning), after a few laps -- sometimes more, sometimes less -- what happens is that suddenly when I go to downshift and slow down for a turn, the engine goes all funny sounding down to low revs, and the car doesn't want to turn right or left. Once I slow it right down to a near stop, then it may work again, or I may have to baby the car into the pits. In the latter case, I can't put too much throttle on, or else it will redline even if 5th gear is selected! After the pitstop, everything works properly again. It seems to me that either my gearbox and/or engine is damaged in the sim itself (is there gearbox/engine damage in LFS, and can it produce the behaviour I'm describing?), or my DFP steering wheel is acting up. Any ideas?

i really doubt its an issue with lfs as ive never heard of it or experienced it by myself.
but i dont use a wheel so lets wait for more opinions.

Tried turning on Tyre view (F9) and damage view (F10) to see what might be wrong? Or perhaps post a replay. I can't really see how it would be the wheel if the problem fixed itself after a pitstop.

As said i would doubt it is the wheel as it fixes itself in the pits. As it does fix itself in the pits it would suggest damage to the car in which case it is more likely to be susension damage ([ress F10 to see) as there is no real damage model for the engine or gearbox.

maybe you ran out of petrol? or you press I to turn engine of?

that surely wouldnt cause such things...

Quote from [RCG]Boosted :

that surely wouldnt cause such things...

Sorry im an idiot
You could try reinstall lfs

Thanks guys for advice and ideas. I'll test it out again tomorrow when I finish work, and come back here with some feedback.

If its a rear wheel drive car you may be locking the rear brakes, this would cause the engine to drop revs and reduce steering, try taking your foot off the brake

Quote from SabersKunk :

If its a rear wheel drive car you may be locking the rear brakes, this would cause the engine to drop revs and reduce steering, try taking your foot off the brake

That's definitely not it. Or at least, putting on my scientist's hat, that the least likely suggestion in this thread. But thanks anyway, it good to consider all possibilities.

I worked out what it was: a tyre blowout. Seems I overheat the left front tyre too much. Any hints for how to avoid that? I'm using the Race_S setup.

Steer less? What car? race_s is usually fine.

XR GT Turbo

learn to drive it smoother, you must be over-driving it in every corner for this to happen. Drive slower into the bends, keep in control, you will exit corners faster and get better laptimes and avoid wrecking your tyres.

Front left? Either applying far too much steering lock, or too much brakes (possibly while steering, you need to ease off the pedal a lot to even use a little steering lock at speed), locking the inside wheel and roasting it.

Is it possible that going off-track can cause a puncture? What can cause a puncture in LFS? Is it random, does it depending on tire temperature, something else? Although my front-left tyre was hotter than the others, it didn't seem that hot (I can't recall the actual temperatures; I'll try again, and write down the temperatures).

tyre temperatures are the most frequent reason to blow tyres, it's less than likely to blow them by bursting from a leak in anything but the BF1.

OK, I just tried it, once again, tyre blowout on lap 5. I closely watched the tyre temperatures this time. The rear tyres were fine and stable, slowly reaching about 60 or so. The right front tire, was around 65 or 70, but fluctuating rapidly. The left front tyre was about 85, even more wildly fluctuating. I must be locking the front tyres, especially the left one, and as the wheel rotates the hot spots are showing up very, very briefly (so briefly that I can't read their temperatures, but they must be higher than 100).

My next experiment will be to race about 5 laps, and then slow down to a crawl, and see if I can capture the temperatures of those hot spots.

So my next question is, how do I avoid locking up the front tyres? I know you might say to drive more conservatively, or take corners more slowly, but I think I'm doing that, and if I go any more slower, I'm seriously going to be a road hazard, and my times will be way too slow.

Can someone please post a default race_s setup? There's a small possibility I may have inadvertently overwritten it, I'm not sure.

Wow, there were spots on my left front tyre as hot as 190, possibly even hotter. It seems I can't drive these cars like I used to drive the old GPL cars. But as I said earlier, if I change my style to much more conservative around the bends, and before the major turns, I can't see myself get decent times, especially with the crappy control these DFP pedals give me (but a good tradesman never blames his tools). Maybe I should play around with the setup, but I've never done that before in a rigorous manner; I guess there's always a first time.

Sorry to be so skeptical about the advice to drive smoothly and not overcook it going into turns, but it seems that all the previous sims I've tried have taught me the opposite, and it's a habit I can't easily break. I will try harder.

P.S. I was reading about the tyre model in LFS. Wow! That is one detailed modelling job.

Driving smoothly actually will give you QUICKER times, even though it feels so slow, an example of which, go watch the SO4R/XRT WR, it looks so slow, but it actually is very fast.

Please post a replay then, I'm getting the idea that you break hard into corners? Entry speed isn't nearly as important as exit speed, but I shouldn't make such assumptions about your driving style without seeing a replay.

Here is a replay, just 3 complete laps.

It's a combination of trailbraking too hard and generally way too strong brakes... race_s I believe? Anyway, by locking up the tires you keep missing apexes by understeering wide... Lower brake force, maybe shift bias a bit towards the rear and generally keep the car straight a tad longer and you should be fine... Just did a (very messy) 3:02 with my slightly edited race_s that way...

Thanks for your advice. I know now what to look for in my replays, so hopefully I can learn to drive more cleaner.