Your engine shouldn't die in that (stupid or not ) situation; you should have it checked at the dealer. Can you duplicate it by revving the car when standing still - hold the revs at 4K or 4.5K for a while (30 sec), then lift off the gas and see if it dies? I know the ECU is too smart and has speed inputs and so on, but it's one test to help diagnose the problem.

A couple of other comments - re slowing down, and engine braking vs. coasting. There's a difference between just letting off the gas in gear vs. downshifting to engine brake, which is what part of those discussions was about. I'd bet that most people will coast IN GEAR, vs. downshifting (bad plan) vs. coasting. Ie, if you're driving in 6th gear at 3000 rpm and you see a stop light ahead, you just let off the gas in 6th gear until the revs drop to 1500 or so, then downshift or neutral.

FWIW, you won't save gas by going to neutral to coast - the engine requires fuel to idle. When you are in gear (above 1500 rpm) and completely remove your foot from the accelerator, the fuel injectors actually are shut off, the engine is not burning ANY fuel when you coast IN GEAR. It is burning fuel if you're in neutral and the engine is idling. If you want to save fuel on those downhill grades, leave the car in gear.

Regards,
Gordon

 

I don't know whether anyone anwered the original question as I blew through the four pages of responses rather quickly.

Does the Renesis employ a Mass Air Flow (MAF) sensor as part of the intake system?

If so, and the intake of air by the engine is suddenly reduced (shifting into neutral) while fresh air is still being delivered to the MAF at the rate associated with 90mph (ram air effect), this results in an extreme change in air flow and causes the MAF to trigger a corresponding change in fuel delivery to the injectors which usually results in a stall.

Just my $0.02 worth... Art

 

What is this? An engineering answer to an engineering question? Say it ain't so! Thanks for trying to take the emotion out of it, Gordon.

 

Well, I too have coasted sometimes in N on a long mile downhill stretch but my car has never stalled. I wasn't going that 80+ mph though.

Didn't know that this was citable.

It's also good to know what to do if that situation would ever occur to me!

Regarding crashunit's car - I'd definitely bring it to the dealer. It's a bug, not a feature.

-Peter

 

Thank you for finally answering my question, and concerns everyone. I figured it was not normal and something I should get checked out. I did a search on this topic before I posted of course, and because the car has less then 2 k on it still, I just wanted to bring this to the forums attention incase it ever happens to someone else. I didnt post about it to ask if coasting in neutral was bad or not. But, apparently some people have almost a serious religion problem with the tabbo of coasting in neutral. So sorry to offend you guys with the way I drive "My Car." Anyways, hopefully like I said before, its just an iscolated incident and not a ecu bug or something. Cause its already throwing up enough ECLs, TPMs, Oil Warnings, and stealing more then enough feul to make me happy with it. I will take it to the dealer and see what they say, and post with the results.

 

Maybe not a religion, but a cult. That's why I took a poll a few months back. When this topic comes up, one camp will dominate saying "Use the brakes to brake, not the engine." Next time, a competing cult will dominate, saying "Save your breaks; keep it in gear down to 1500 rpms." This particular go-round was a bit bloodier than those in the past, but in the end no more definitive. As you say, it is your car; drive it as you damn well please. You certainly got more flack for this valid question than the punks who are sharing tips how to take off from red lights to show that Z in the next lane who's badder. On balance, I would feel much safer having you drive in my neighborhood than the punks, yet I didn't see any moralizing on their thread (other than myself, and I left when no one else jumped to my defense.)

Good luck. Your new "handle" is Coaster!

 

Haha, thanks, I was meaning to actually reply to you, but I was caught up having to defend my own post to keep it on topic. Luckily it did, and I actually got a PM thanking me about bringing it to the forums attention believe it or not. Apparently its some what a concern your car shuts off by itself. This just happened to me a second time last night, so I thought I would post about it in the morning to get some replies,which was a rally bad Idea. Since, I am then welcomed to "nuetral ****'s" who I have to spend 4 pages of irrelevance with, till I got some decent replies. But whatevers, you learn something everyday, and for me, its never to post in the morning again .

 

Ok, straight to the source:

"Mountain Driving

21662. The driver of a motor vehicle traveling through defiles or canyons or upon mountain highways shall hold the motor vehicle under control at all times and shall do the following when applicable:

(a) If the roadway has no marked centerline, the driver shall drive as near the right-hand edge of the roadway as is reasonably possible.

(b) If the roadway has insufficient width to permit a motor vehicle to be driven entirely to the right of the center of the roadway, the driver shall give audible warning with the horn of the motor vehicle upon approaching any curve where the view is obstructed within a distance of 200 feet along the highway. "

So first of all, a downgrade on an interstate is not "mountain driving", so the rule isn't applicable in this case. Secondly, define "under control." Coaster met the reqts of paras (a) and (b) which really aren't relevant in the instant case, besides which he was under control. What if you're coasting in gear but your foot off the pedal. ARe you any less "in control?" Would this be punitive under 21662? Get real.

Referece for the above, from
Cal DMV web site. Sorry, matt, the officer was just giving you a line so he could get you off the phone and back to his donuts. Next time, do a little authoritative research.

 

Yeah, Im sorry, I dont have the slightest clue where you got coasting in neutral meant you are completely out of control. If that ever happened to me, I would never have done it! I only did it cause it was convenient to do so imo. Maybe if you ever try it, you will see it is not all that bad, and I am not jeopardizing my life in doing so. But thanks for your concern I guess.

 

Well done 8_wannabe! When I asked matt for some proof, he just refered me back to his original claim, and I was too busy to look it up myself, and frankly, didn't care about some asinine law on the books that has no practical implications.

In anycase, its funny that matt stopped posted after his asshatted-ness has been confirmed

but..i do disagree with this: "You certainly got more flack for this valid question than the punks who are sharing tips how to take off from red lights to show that Z in the next lane who's badder. On balance, I would feel much safer having you drive in my neighborhood than the punks, yet I didn't see any moralizing on their thread (other than myself, and I left when no one else jumped to my defense.)"

The question was about launches and starting at higher speeds. Lets be practical, what does launching very rarely have to do with morality. This is a sports car, and obviously noahprtlnd's is equpied w/ a manual tranmission, meaning he has the *ability* to launch at 6000-7000 rpm.

Don't tell me that majority of people here don't get the urge to drive their car hard. For me, the funnest part of driving hard is actually when there isn't anyone ANYWHERE around. For noahprtlnd's post, I gathered that he wanted to autocross, and wanted to know *before* trying it what the car would do, so he would be ready, and therefore *NOT* risk harming himself or others. Knowledge is power, as TV tells you.

You're reflecting some image you have of the modified honda kiddies running around your neighborhood + the fast and the furious sect that you seem to think was the impetus of noahprtlnd posting. As a matter of fact, that Punk holds an M.D.

Life isn't binary. And, rightly so, aren't morals.

 

Have you ever been blasted with a gust of wind while driving? If that happened at 90 mph in neutral and you countersteered, what do you suppose the chances are of the rear end continuing downhill while you are correcting right. Bad situation. If you never have to turn while coasting, then you will be fine, but is it worth the chance? These cars do not have 4 wheel steering. When you turn the wheel, only the front turns - not the rears. Depending on the road surface, rate of turn, etc., you could put yourself into a spin - especially with no GO available to help correct any oversteer.
In any case, the car should not stop running in neutral - ever.

 

Hi Crashunit,
First let me address your question, your problem with the engine shutting off by itself could be related to Fuel Starvation. There were some cases here where people reported their engine unexpectedly shuts off when they are running low and they think it could be Fuel Starvation. Do you remember how much fuel you got in your tank when your engine died on you ?

In any case please take your car to the dealers as this quite seriously I think. On the note of saving gas. I would suggest maybe just putting your car in 6th gear, you will probably get the same result. This is because the 6th is actually a Over drive gear, meaning per engine revolution, the wheel spins one revolution and a little bit ( 1.19 wheel revolution per engine rev to be exact). So therefore when going down a slope, the amount of engine "braking" with your foot off the gas should be minimal.

Give it a try and see which way feels smoother for you.

 

Wow! :p
Harsh, illogical and gratuitous - all in one post. Good job Matt. Like some fries with that?

Engine braking will not improve your breaking ability at all. If you are talking about the vacuum assist, it will hold vacuum for HOURS without additional help.
CrashUnit's behaviour is neither adolescent not does he seem to be a "know-it-all" anymore than you do by this post.

That said, most states do have a law specifically against coasting more than 500 feet in neutral. It is mostly about culpability in an accident than actual safety.

Moreover - fuel consumption is about pedal position. If you leave the motor in gear and your foot off of the gas, you will consume LESS gas during that period because your motor consumes a small amount of fuel as it idles, but consumes NONE during engine braking because the fuel delivery is cut as part of the "anti-bucking" routine written in the ECU code during zero TPS output at elevated RPMS (over 1700).
In short, if you are moving:
neutral + foot off gas = idle fuel consumption
in gear + foot off gas = no fuel consumption

Your choice, but it isn't adolescent.
Adolescent is pulling the e-brake at those speeds.:p

 

I tried for the hat trick!

Fries are bad for you. Too much fat

 

Ugh. Everyone calm down, take a deep breath, and type in a polite manner.

 

This is one of the funniest threads I've read in a while. I really wouldn't care if driving down a hill in neutral is illegal or not, or if it saves gas or not, I wouldn't do it because it's bad for the motor. While a vehicle is running at idle the oil pressure is at it's lowest, mechanics will tell you not to let your car idle for long periods of time. If you're coasting downhill in neutral often I'd be a bit worried about the longevity of your motor.

 

So after all this bickering did the question get answered? lol. I read the first page and it was just UN-NEED bitchin i didnt even read the next couple pages. gez.

well I dontknow much about rx8s I have a secdon gen 7 but what i do know is when you put it back in gear while doing 80 and the car starts back up . Thats basically like rolling your car and poping the clutch to get the engine started. THats normal especialy if you have the key in the ON position. but for the car to die out like that... hmmm. I duno. thats just not good.

Justin -

 

Coasting down hill in neutral isnt going to hurt your motor AT ALL. your in neutral..the engine isnt turning the tranny. OR i should say the tranny isnt turnning the engine. Oil pressure would be low cause the rpm is probubly down near 800rpm. The engine dones't even know your coasting. all it knows is that its idling as if it was idling in your driveway.

Justin

 

hi everybody!! how have you been? anyway i just thought i would speak up on this. i noticed a few people suggested going to a dealer. this will not work. the reason is the speed. no dealer will test drive your car at that speed. no matter what. i would be very surprised if you found a dealer wiling to drive that fast. and since it does not happen at lower speeds. i think you are sol with this one. but please post if you do a find a dealer that wil test drive a vehicle over the posted speed limit. and before flaming this rememeber the mechanic has to follow the laws of the road if he wants to work, besides i really dont think any dealer wil allowan employee to drive that fast because it could also cause an accident. i work at a mazda/mits dealer and yes we do have some customer teling us things happen at high speeds and no we do not test the vehicles, we go the posted soeed limit and if it hapens it happens. so i just recomend to stop putting it in nuetral at that speed and just take your foot of the gas pedal. it would be safer for everybody!!

 

I dont know why mazda dealers dont have a dyno.. Theyould figure our so many problems if theyhad one. Its stupid. But I dont want to turn this thread into a fighting war like it was earlier.. oooff

Justin

 

Okay, I'm sorry to continue the animosity in this thread and other similar ones, and am sorry that ibfubar is an example here - but I am sooooooo tired of the f*cking policing going on in this SPORTS CAR forum! This is not the Buick Park Avenue forum...and I know ibfubar was just giving a view of someone that works at a dealership, but its just an example of the kind of crap people are posting on this forum in response to simple questions regarding their car. Guess what? some of us bought a $30000+ SPORTScar and want to drive it as such. I don't know if some of you lost people close to you in accidents and so are sensitive about the subject, or what. But get over it. People will drive however they want - if they get a ticket, that's their problem and it was their decision to speed/drop the clutch/put it in neutral or whatever else they choose to do with the car they bought. Please spare us the Nader taking someone innocent routine. Start a Road Safety forum if that's what you want to talk about.

 

Listen amigos. First off:

Why isnt the governor at 70mph? WTF. The dealer MUST acknowledge the problem with the car, regardless of the *law* on public streets. You can drive as fast as you like on your own property/track if you are so lucky to have one, and the dealer cannot claim that the reason s/he won't fix your problem is because to find it would be going too fast. The point of reporting it is so it goes to mazda, and if they've had this problem in other cars, and have a solution, crash can get the problem solved :P

Good luck crash old boy.

And why would a dealer have a dyno. What good would it serve, and what problems would it solve?

And to noahprtlnd: I'll decide soon whether you're an asshat. But you make a great point.

 

S'cuze me while I hitch up my hipwaders.... it a-gettin' deep in here.

 

Actually, the shop procedures often call for a dyno for some of the diagnostics to be done correctly.
Most dealers opt for a portable WDC (i.e. - laptop) and datalog instead a chassis dyno. Somewhat cheaper and takes up less floor space that could be filled with other vehicles getting improper service and making obscenely big bucks.

 

The dealer is closed tomorrow, since it is Thanksgiving, so I will probably bring in the car on Friday. I have a really good relationship with the Alhambra Mazda dealership cause of my 3rd gen FD, and everyone at the service and parts department know me. I am sure they will get to the bottom of this for me, and help me fix it or find out why. If they do take the RX-8 up to that type of speed or not, shouldn’t matter, if its a problem they should just call higher up till someone at headquarters or engineering knows why it is doing this. And if it is really a problem where a lot of people are complaining about it, I’m sure they could just take one of the company's RX-8 out to the Mazda proving grounds where they can test it in a closed and safe track facility.

Besides this, however, I just spoke to one of my friend who has a G35, and oddly enough owners are having the exact same problem with the G35 as well. Plus, to make it even more bizarre, the thread on it started out just like mine . With people bickering, people being stupid, and not answering the question or keeping it on topic. Supposedly though, the G35 owner's car would die between a slow shift when he was in neutral. I guess in our cars, the tach takes quite awhile to drop and rise thru RPM's, while the G35 drops a lot faster and just dies out, till he pops the car back into gear.

As stated before, " No car should just turn off by itself, no matter what the circumstances are." Its just too dangerous, and impossible to be safety feature on a car. And even if it was, dealers and companies should defiantly warn its customers the car is capable of turning off by itself while in motion. Even if it doesn’t do anything really to cause an accident initially, just seeing the car die, is quite a shock, and freaking out and doing something stupid could really hurt someone unfamiliar with a car. Luckily for me (or unluckily), I have had a car die on me while in motion before, so it wasn’t too big of a shock that I didn’t know how to react to it. But I guess, since I have brought it to everyone’s attention already and I don’t want people to panic if it happens to them, just remember to pop it back into gear. The car will still be running, and brakes will still work like normal, so don’t freak out. The only thing you wont be able to do unless you get back into gear to turn the car on again, is you will not get any power from the motor to speed up. Your DCS will also be turned off while this happens, but steering feel and brake feel, will remain the same as if it didn’t turn off. Hope that helps. I really want to get to the bottom of this, so I will post again soon if I find out anything else.

- Marvin