Mazda car radios getting stuck on NPR - Page 1
Forum section: electronics / general

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 12, 2022, 02:56:04 am
content: https://arstechnica.com/cars/2022/02/radio-station-snafu-in-seattle-bricks-some-mazda-infotainment-systems/

author: Kim Christensen
author_rank: Super Contributor
timestamp: February 12, 2022, 03:30:32 am
content: Well, that's just crap coding at it's finest.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: February 12, 2022, 03:43:54 am
content: And what happens if something like this happens again after the car warranty runs out?edit. I mean much later on. When nobody at mazda remembers how this stuff works.

author: MrMobodies
author_rank: Super Contributor
timestamp: February 12, 2022, 04:12:19 am
content: QuoteQuoteHow can they allow radio stations and broadcasts to interrupt their system at a firmware level.I don't remember this ever happening with car radios or consoles whatever they are called.

author: AVGresponding
author_rank: Super Contributor
timestamp: February 12, 2022, 09:02:41 am
content: Quote from: Ed.Kloonk on February 12, 2022, 03:43:54 amI doubt anyone at Mazda knows how this stuff works, it'll be designed and manufactured by some third party like Matsushita or Samsung, or as it's North American market maybe Motorola or someone?

author: sleemanj
author_rank: Super Contributor
timestamp: February 12, 2022, 09:40:50 am
content: I hate how cars have gone to all these fully integrated systems, my $20 Aliexpress MP3 playing DIN slot headunit does me just fine.

author: BrokenYugo
author_rank: Super Contributor
timestamp: February 12, 2022, 06:12:04 pm
content: Quote from: AVGresponding on February 12, 2022, 09:02:41 amDoesn't seem to matter who or where it comes from, automotive is just sloppy like that. I'm reminded of the Toyota "unintended acceleration" fiasco, when it came out that the ECU was full of spaghetti code and single random bit flips could make it pin the throttle, among other horrors. If Toyota was screwing up that badly I'd assume their generally lower quality (IMO) competition is worse.

author: MrMobodies
author_rank: Super Contributor
timestamp: February 13, 2022, 04:09:17 am
content: Quote from: BrokenYugo on February 12, 2022, 06:12:04 pmI remember that, they blamed driver error, floor mats and I read the authorities started to take more notice and investigate when some highway officer and his family got killed in one of them.I last read they got fined for it.https://www.latimes.com/archives/la-xpm-2010-mar-03-la-fi-toyota-saylor3-2010mar03-story.htmlQuote

author: Haenk
author_rank: Super Contributor
timestamp: February 13, 2022, 09:37:09 pm
content: Quote from: MrMobodies on February 13, 2022, 04:09:17 am"pedal stuck" is not a software thing, still that should never ever be possible

author: Cerebus
author_rank: Super Contributor
timestamp: February 13, 2022, 11:20:17 pm
content: Quote from: Haenk on February 13, 2022, 09:37:09 pmI think the only people who have thesang-froidto be precise and say "The accelerator system has become unresponsive to control inputs" when in a vehicle heading at top speed down a road that ends in half a milealsonormally have Martin-Baker ejector seats to get them out of trouble and a brand new necktie in their near future. For the rest of us I suspect screaming "The ******** pedal's stuck!" is the nearest we're going to get to terminological exactitude under those circumstances. So there's no reason to believe that the description does not fit a "software induced failure in the acceleration system" any less well than it describes a simple mechanical failure.

author: AVGresponding
author_rank: Super Contributor
timestamp: February 14, 2022, 07:16:03 am
content: If you've time to make a phone call (even as a passenger), I'm surprised there wasn't time to try things like force it into a lower gear, or reverse (you might break the gearbox, but at least you're no longer accelerating), or even just turn the engine off (without completely removing the keys obviously, don't know if that model is keyless though).

author: SeanB
author_rank: Super Contributor
timestamp: February 14, 2022, 09:36:21 am
content: Lexus has been keyless for a while, top end model range almost always are these days. Probably also locked out shifting down a gear to protect the gearbox, and thus the shift does nothing, as it is also just a set of logic inputs to the drivetrain controller, with no actual linkages any more. Might have reset if you held in start stop button for 30 seconds, but kind of hard to read the manual while being in a semi guided missile.

author: voltsandjolts
author_rank: Unknown
timestamp: February 14, 2022, 11:13:34 am
content: Click it into neutral?I guess panic had set in.

author: WatchfulEye
author_rank: Regular Contributor
timestamp: February 14, 2022, 11:40:08 am
content: Certainly at the time Toyota was under fire for unintended acceleration, there were significant usability issues with the keyless system.I had a lexus at the time and given the fuss, I thought it would be sensible to check functionality so that I had a plan. So I found an empty road and drove at 10mph while I tested mitigation strategies.Pressing the start/stop button was my first thought. This did nothing at all.Repeatedly mashing the button also did nothing.I had to hold the button for what was a very disconcerting period of time, even at 10mph, although it was probably only 5 seconds.Pushing the transmission lever into neutral worked perfectly and this was the obvious best choice out of the solutions tested.It was fortunate that I had done this, as about 1 year later the car suddenly accelerated uncontrollably as I pulled out of a junction. I popped it onto neutral and coasted to a stop with the engine bouncing off the limiter.The cause in this case was easily identified. The pedal had become Mechanically caught by the floor mat, when I had floored it to make a quick getaway from the junction.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 14, 2022, 01:20:38 pm
content: Quote from: WatchfulEye on February 14, 2022, 11:40:08 amThe floor mat in some cars (I've seen it in Fords) has a small hole that a hook engages (from the floor), to prevent the mat sliding forward. Should really be mandatory...

author: AVGresponding
author_rank: Super Contributor
timestamp: February 14, 2022, 08:18:25 pm
content: Quote from: SeanB on February 14, 2022, 09:36:21 amIt's quite troubling to realise that, especially with the ubiquity of electronic controls over physical ones nowadays, manufacturers seem to be happy to ignore the concept of fail+safe.

author: BrokenYugo
author_rank: Super Contributor
timestamp: February 15, 2022, 12:43:43 am
content: Quote from: AVGresponding on February 14, 2022, 07:16:03 amFor the record, the correct action is to stand on the brake pedal until the car stops. Assuming the brakes aren't half functioning worn out junk, this will stop the car.

author: Cerebus
author_rank: Super Contributor
timestamp: February 15, 2022, 01:02:35 am
content: Quote from: BrokenYugo on February 15, 2022, 12:43:43 amTFTFY

author: SilverSolder
author_rank: Super Contributor
timestamp: February 15, 2022, 03:30:49 am
content: It matters what kind of car the throttle sticks on... if it is a Toyota Corolla, the brakes can probably win over the engine. If it happens in your supercharged hot-rod, you may have a problem!

author: Monkeh
author_rank: Super Contributor
timestamp: February 15, 2022, 04:48:32 am
content: Brakes are sized according to vehicle mass more than anything else. They are not, as I understand them, intended to stop a vehicle at wide open throttle, especially if you already have significant momentum.If you find yourself on an empty stretch of road suitable for trying it, please, feel free. Myself, I value my brake components and would prefer not to ruin them testing this, when I can simply take the vehicle out of gear.Quote from: WatchfulEye on February 14, 2022, 11:40:08 amA classic case of 'driving like a twat'..

author: Cerebus
author_rank: Super Contributor
timestamp: February 15, 2022, 05:13:14 am
content: Quote from: Monkeh on February 15, 2022, 04:48:32 amAs my mother would say: "Takes one to know one!".

author: Someone
author_rank: Super Contributor
timestamp: February 15, 2022, 06:15:42 am
content: Quote from: SilverSolder on February 15, 2022, 03:30:49 amBrakes are going to overcome the engine of pretty much any road going (combustion engine) car. Stalling a runaway diesel in 1st gear? no problem, and thats close to corner case worst possible situation.

author: Cerebus
author_rank: Super Contributor
timestamp: February 15, 2022, 03:38:17 pm
content: Quote from: Someone on February 15, 2022, 06:15:42 amTry it. You're in Aus, and if there is anywhere in the world you can find a long, straight, unoccupied road it's in Aus. You might be surprised.Fullthrottle remember,notidle.Alternatively you can work it out mathematically. My car produces 174 Nm at the engine shaft, 559 Nm at the rear shaft in 5th gear, 2314 Nm in 1st. That's a lot of torque to overcome. The brake force calculations versus engine torque are left as an exercise for the student but I've just done them on the back of an envelope and it's surprising. The engine wins.Also the 143 BHP (107 kW) my car's engine produces is a lot of heat to get rid of from the brake discs. A brake disc is cast iron and weighs 4.5kg or thereabouts each, they have a specific heat capacity of 460 j/kgK and a melting point of around 1150 C, so need 9.35 MJ to raise the temperature of 4 x 4.5 kg = 18 kg discs to melting point from 20 C, which is just 87 seconds at 107kW ignoring any cooling (which wouldn't be very much). Anyone who has done any racing will tell you how quickly brakes fade once they get too hot.

author: jmelson
author_rank: Super Contributor
timestamp: February 15, 2022, 06:48:01 pm
content: Quote from: AVGresponding on February 14, 2022, 07:16:03 amThe Toyota Prius does not have a traditional transmission, it has a fixed planetary gear set between 2 motors and the IC engine. Reverse is accomplished by running the electric motors backward and the IC engine stopped.Their drivetrain control had something like 46 tasks, and the LOWEST priority task was monitoring the BRAKE pedal! YIKES! When overloaded, the real time manager would drop lower priority tasks. Supposedly, holding the "power" button for 4 seconds provides a hardware shutdown of all electronics that can't be overridden by software, and would have caused the car to coast to a stop. The gear shift on the dash is obviously just a set of switches that are read by the drivetrain computer. The Prius has no "ignition key/ignition switch" it just has a "power" button. The key fob has to be somewhere near the dash for the immobilizer to detect it.Jon

author: Someone
author_rank: Super Contributor
timestamp: February 15, 2022, 11:46:26 pm
content: Quote from: Cerebus on February 15, 2022, 03:38:17 pmI said runaway, not idle. So something in the order of 4000Nm at the wheels, in first gear, engine stopped no problem. You jump to maths to try and justify your imagined truth but there are some basics which immediately point to it being wrong:Combustion engine cars decelerate faster than they can accelerate, even if you take a car that can freely spin the wheels under power, when stopping hard ABS pulls down peak stopping force on the brakes to maintain traction.Cars dont have brake fade from a single pull to stop from cruising speed, its something thats actually physically tested for Australian design rules compliance (15 back to back partial declarations).So these things have been tested, it might be that the brakes on my vehicles are wildly high performance but being stock from the factory I dont think they are anything special (they do have highly non-linear servo assist for emergency force, but that should be fairly commonplace, again its something tested by the ADR compliance). Depending on region in Australia you are looking at 0.4 to 0.6g as the minimum braking force to meet roadworthy testing, which is more than enough to arrest regular engines, oddly enough high power vehicles have higher performing braking systems...

author: Cerebus
author_rank: Super Contributor
timestamp: February 16, 2022, 12:27:08 am
content: Quote from: Someone on February 15, 2022, 11:46:26 pm"You jump to maths to try and justify your imagined truth" - Well, put some cold hard numbers on what you're saying then. On an engineering forum numbers are facts, everything else is opinion or hot air.

author: Someone
author_rank: Super Contributor
timestamp: February 16, 2022, 12:43:24 am
content: Quote from: Cerebus on February 16, 2022, 12:27:08 amSo you can throw up misleading and incomplete models and claim you are more correct? No. Especially when your claims are directly contradicted by actual testing. You think the engine wins, I have done that specific test (in close to worst case) and found the opposite.You put up some maths for some tiny fraction of the problem, and couldnt be bothered to check real world figures/sources. But ask me to justify?... Oh wait, I did:https://www.infrastructure.gov.au/infrastructure-transport-vehicles/vehicles/vehicle-design-regulation/australian-design-rulesEntirely yours to peruse, the mandatory testing that road going motor vehicles must meet to be registered in Australia. That proves brakes are capable of pulling up, repeatedly, without failure. Energy dissipation is not the problem, clamping force/friction is likely the limiting factor (if it wasn't then brakes would be ripped from their mountings in emergency braking), yet all realistic road going cars with combustion engines decelerate faster than they can accelerate, energy in vs energy out, such a simple physics principle. Therefore they can easily shed speed even if the engine is running full tilt.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 16, 2022, 01:01:08 am
content: Quote from: WatchfulEye on February 14, 2022, 11:40:08 amWeird stuff happened, even prior to the widespread use of microprocessors in cars.My 1983 Holden Camira (a "beefed up" version of GM's "J" series "world car") had a nasty little trick, in that, if you intended to accelerate briskly from a standstill, the car would, instead, trickle away at a "snails pace", so you could find yourself part-way across an intersection with a large truck bearing down on you.At the beginning, it sometimes wouldn't do this, so when I "took it back", the verdict was NFF.As we were moving to a country town for work, & it was only really a problem if you needed to "take off" relatively fast in a few traffic situations, we didn't have the time to chase Holden about it, so, perforce, we developed a technique for these situations, where you floored the pedal, let it up, then immediately pushed it again, when it would operate normally.This was not often needed in the country town, as, if you were joining a main road, you could usually see the "ginormous" wheat truck coming a fair distance away, & decide your options.As being carless in a Wheatbelt town while I was at work wasn't a preferred option for SWMBO, we went back to Perth, & picked up a old "roughie" for me to drive-------a V8 Leyland P76!The tyres weren't the best, so another trip to Perth to equip the old beast became necessary.All good, so far, until I was stationary at traffic lights.The lights went green, & momentarily, I forgot which car I was driving, & floored the throttle.The results were impressive, to say the least!It was just as well that I was replacing the tyres, as the old "P seventy-thing" probably left most of the remaining rubber on the rear ones behind!Epilogue: I found out later that the Camira's "vacuum logic" "Engine Management Module" had two hoses transposed.Connecting them correctly fixed the fault.

author: Cerebus
author_rank: Super Contributor
timestamp: February 16, 2022, 03:07:09 am
content: Quote from: Someone on February 16, 2022, 12:43:24 amNo, you haven't justified or proven anything, just engaged in handwaving and vaguely alluded to "testing it" without providing any details. Let me be clear, I'm happy to be proved wrong by someone that puts the work in, even tells a convincing anecdote of when it happened to them, or how they tested it, but someone who just gainsays, and insultingly at that isn't adding anything useful to the conversation.If you want to cite what I expect is hundreds of pages of Australian Design Rules, you could at least quote the paragraph that proves your point, possibly with a little extra explanation if it doesn'tdirectlyprove your point, but you don't. Failure to do so smacks of rhetorical tactic rather than an attempt to impart actual information - "Here, here's a 500 page document that proves I'm right, read it. Then when you have you're fit to discuss this". No, thank you."That proves brakes are capable of pulling up, repeatedly, without failure." undernormalconditions of repeated braking I'm sure they do and I'm sure the ADR makes sure they do. Brakingcontinuouslyagainst an engine locked on full throttle isn'tnormalconditions. But I must assume you know that, yet you still cite it as "justification". Again, rhetoric, not a useful factual contribution. You''ll have to forgive me at this point if I come to the conclusion that that you're more interested in bolstering your opinion than arriving at some objective proof.So, will a modern car's brakes stop it if the engine has run away at full throttle?I'd like to see a complete, calculated example from someone who knows what they are talking about rather than all the opinions and conjecture. "someone" clearly can't provide it, I'm pretty certain I can't (the reason for leaving my back of the envelope calculations to one side is (1) there's one point I don't completely trust, (2) I was rather hoping someone better than me would stick their oar in).So, instead of bluster, handwaving and insults would anyone care to try for areasonedsolution like grown up engineers?For completeness here's the back of the envelope calculations I did earlier. I actually put them to one side to have a think later, then got interrupted by someone who thought that the route to wisdom is pathed with handwaving and gainsaying.=======================================My car will produce 174 Nm at the engine shaft, 559 Nm at the rear shaft in 5th gear, 2314 Nm in 1st. I have "10 inch" brake discs the pads are about 2" across so let's take off 1" to find the centre of the pad's contact area. That gives a radius of 102 mm. Calculating back, assuming perfect brake pads and discs with a coefficient of friction of 1, you need to provide 559Nm at 0.102 m = 5480 N force at the brake pad to overcome 5th gear, and 2314Nm at 0.102m = 22686 N to overcome 1st gear. That's crudely 559 kgf and 2314 kgf.Can I produce forces between 559 kgf and 2314 kgf on the brake pedal? No. Can I do it with the help of a vacuum servo? The biggest vacuum servos normally fitted are 11" and those have a force multiplier of around 2.4. So the question becomes can I produce between 233 kgf and 964 kgf at the brake pedal? The answers are respectively "No" and "No.".But, the brake pedal provides mechanical advantage. How much? If it was 2:1 you can halve those figures. So I might be able to beat the engine at full throttle in 5th, I wouldn't stand a chance in 1st. If it was 5:1 then in 1st I'm down to 192 kgf, a bit more than twice my body weight - I might just manage that to save my life. In 5th we're at 46 kgf, a bit more than standing from a squat, definitely doable. So, we're down to the questions (1) what mechanical advantage is available, (2) what gear is the car stuck in before we can get to a plausible answer.Note that we have completely ignored the momentum of the vehicle, just the force required to overcome the engine. If we want to do momentum too we'll have to get into differential equations, and nobody wants that do they? And then there's brake fade, that assumed perfect coefficient of friction is (1) false, (2) will rapidly become less as the brakes heat up, which is a fair assumption in this scenario.=======================================My sticking point is that I'm uncertain how much to account for mechanical advantage at the brake pedal. That's simply because I couldn't find any figures, whereas oddly I could find figures for the effects of servo assist for different size servos (I assumed the biggest available, I wasn't going out in the rain to check). Go figure.Now, if anyone sensible can find fault with that please do and correct it. Perhaps we can work towards facts rather than conjecture and opinion.What I can say from anecdote, is that in olden days it was a reasonable test of a handbrake to see if the car stalled trying to pull away with the handbrake on. Much to my embarrassment, I have to confess to having driven off with the handbrake on in the car cited above and got up to 30-40 mph (turning right from traffic lights from a Sainsbury's car park onto the North Circular Road, the embarrassment is sufficient that I rememberexactlywhere I was), wondering why the car wasn't pulling properly, before I realised that I still had the handbrakeon. And no, that's with a fully operational and MoT tested set of brakes (which requires that each wheel produces at least 100 kgf braking force on a rolling road, so 200 kgf minimum at the tyre for the two rear wheels operated by the handbrake, 575 Nm minimum if converted to torque terms).

author: Someone
author_rank: Super Contributor
timestamp: February 16, 2022, 07:03:50 am
content: Quote from: Cerebus on February 16, 2022, 03:07:09 amYou really are a masochist arent you?https://roads-waterways.transport.nsw.gov.au/documents/roads/registration/brake-assessment-manual.pdfBoring car, 8000N of stopping force at the wheel/road interface from the front wheels.... pedal force 547N. So you're still out by an order of magnitude. Regular cars are no challenge to stop with their braking system, modern disc brakes are astonishing in their power.

author: Haenk
author_rank: Super Contributor
timestamp: February 16, 2022, 08:19:29 am
content: I think this is more a matter of "how to brake". If you are apply too little force over a longer period, you will destroy the pads and discs due to overheating, the brakes will hardly brake any more (this is a common failure on the combination of heavy vehicle, mountain and inexperienced driver). If you instead floor the brakes, your vehicle *will* stop. Of course you should not try that for fun for safety reasons...

author: Cerebus
author_rank: Super Contributor
timestamp: February 16, 2022, 12:58:40 pm
content: Quote from: Someone on February 16, 2022, 07:03:50 amAgain, pointing at some document off in the distance is not making your case, it's just ducking having to prove it. Still if that's the way:The MOT Inspection Manual.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 16, 2022, 05:21:45 pm
content: I know someone that experienced a stuck wide-open-throttle in a powerful V8 sports car on a downhill section of road. He stood on the brakes, which were just about able to slow the car enough to make the final crash merely "expensive" rather than "fatal"...I lost control of a car myself once, flooring it in a turn... the throttle stuck and the car spun out at the exit of the turn, despite turning the key off very fast (I was young, with good reactions, which didn't make up for the poor decision making on this occasion!).

author: mc172
author_rank: Frequent Contributor
timestamp: February 16, 2022, 10:47:33 pm
content: Quote from: Cerebus on February 15, 2022, 03:38:17 pmCuriosity got the better of me on the way home from work tonight so I gave it a go in a 1.6 litre supercharged R53, 168 BHP, 220 Nm, 6 speed manual. The power and torque figures are peaks, but it's apples to apples from your example. They're measured at 6k RPM and 4k RPM respectively for peak figures if you're interested, or so some website says.I floored it and applied the brakes in third, then second gear, at 30 MPH. Engine speed was 2200 RPM in third and 3100 RPM in second at 30. In third I was surprised at how quickly the car slowed down and couldn't get to the clutch quick enough to stop stalling it as I was watching the revs and speed, and the road, so there I was in the middle of a clear road with nothing in front of me, no reason to have stopped, restarting the car...I tried the same in second and only went down to about 15 MPH. It was noticeably more difficult to slow the car down but it at no point felt like it wasn't ever going to happen, or run away. It was still slowing down at a decent rate. I was of course left-foot braking which itself is a strange experience, coupled with flooring it as well it felt like there was quite a lot going on, especially judging how hard to press the brakes with my left foot as usually that's going straight to the floor.I didn't try first gear as the roads weren't exactly deserted and I didn't want to look like a total nutcase, driving around slamming the brakes on for no reason other than to conduct stupid experiments.In most cases I'd be driving around in 4th at 30 MPH, somewhere between 1500 and 2k RPM, coupled with the less advantageous torque multiplier from the gearbox and diff.

author: Monkeh
author_rank: Super Contributor
timestamp: February 17, 2022, 12:06:46 am
content: I remain curious as to how this would go at motorway speeds in a two tonne American compensation-mobile which has begun to accelerate madly by itself.

author: WatchfulEye
author_rank: Regular Contributor
timestamp: February 17, 2022, 01:32:22 am
content: Quote from: Monkeh on February 17, 2022, 12:06:46 amThis experiment has been done by several car magazines, for example:https://www.motortrend.com/features/unintended-acceleration-test/https://www.caranddriver.com/features/a16576573/how-to-deal-with-unintended-acceleration/The results of these tests are that most cars stop almost as quickly as if the accelerator was not depressed. The only exception was a muscle car tested at 100 mph where stopping distance was extended by a couple of hundred meters.There are, however, some problems with these tests - as they did not test the worst case (i.e. the maximal brake pedal effort achievable by a physically weak driver, rather than an average driver or an athletic driver), nor do they take account of the fact that brake assistance will be rapidly lost if the pedal is pumped. Without brake assistance, the results are likely to be significantly different.

author: AVGresponding
author_rank: Super Contributor
timestamp: February 17, 2022, 06:40:04 am
content: Given that the case in point was a serving police officer, it's unlikely he was unable to provide enough pedal effort. One wonders at this point just how much separation happens between the brake pedal and the braking system on this vehicle; I'm not specifically aware of any braking-by-wire systems, but of course that doesn't mean they don't exist.If these cars have an "intelligent" cruise control system, ie one that can brake as well as accelerate, I wonder if the car had already been braking slightly to compensate for the engine gradually throttling up, and when the driver tried to apply full braking the brakes were already hot and didn't have enough retardation available?

author: Haenk
author_rank: Super Contributor
timestamp: February 17, 2022, 08:30:35 am
content: Caranddriver states an interesting fact: When going at high speed (that Lexus should be able to reach 120mph easily), the brakes were not enough to actually stop the car, just to slow it down to a lighter crash.

author: mikerj
author_rank: Super Contributor
timestamp: March 01, 2022, 10:46:38 am
content: Quote from: Cerebus on February 15, 2022, 03:38:17 pm559Nm is a trivial amount of torque for brakes to overcome, a hard stop even from low speed generates far more than that. The problem is if the car is already travelling at significant speed then there is already lot of energy for the brakes to absorb, and having the engine working against them at the same time could push them over the edge if they were marginally sized to start with.

author: BrokenYugo
author_rank: Super Contributor
timestamp: March 01, 2022, 08:05:50 pm
content: Quote from: AVGresponding on February 17, 2022, 06:40:04 amI know Prius (at least gen 3) is brake by wire in the rear, it pumps them up for the parking brake (no pawl in the transmission), you have to put into a service mode to do any work on them. The fronts that do most of the work still have a direct hydraulic path for safety though.