dillsrotary

Do you usually drive around with barely any fuel in the tank? I'm not saying that you ran out of gas, but fuel in the tank is what keeps the fuel pump from overheating. My guess is the fuel pump is dying.

klepto

So turn off DSC (pressing the DSC button 7 seconds while car is on) then reset the DSC (turn off car and restart car) and then drive to recreate the issue?

klepto

I usually don't let it go below 1/2 tank. But w/the rise in gas prices I have let it go till 1/4 and then fill up. Doesnt make sense but it does because it requires less visits to feed the 8. So the answer is no I don't ride around w/out gas.

I had a lil less than 1/3 of a tank left and almost arriving to my destination.

alz0rz

iTrader: (41)

Nah, after you turn off DSC with the car on (by holding it for 7-8 seconds or until both lights are on the dashboard) just drive it and try to recreate the problem. If you turn the car off and on the DSC will come back on.

klepto

OK...LOL...I havent driven my car w/the DSC off yet. And you want me to recreat an issue...LOL...I think I'll pass on that one for now. Considering I'd be doing 80+ on a highway. I don't that is a smart move bro but thanks.

alz0rz

iTrader: (41)

Wait, does this happen when you jam down on the brakes? or when you ease into the brakes like just to slow down..

Unless you are JAMMING down on the brakes enough for ABS to kick in (like foot all the way down)... it won't be a problem. I turn off my DSC every time I drive.. I hate my ECU correcting me when I take a turn too quick..

People drive RWD cars without DSC ya know.. In fact the RX8 base has no DSC to speak off!

maxxdamigz

iTrader: (1)

So the trans literally has a sensor feeding back what gear you are in? That seems highly redundant given that you can get all the info you need from the wheel speed sensors and rpm as well as the speedo and determining gear that way would not likely lead to a gear dependent failure. Meh. Engine load is generally read off the TPS. Anyway, this is getting off topic. I'll look into it more when I get my car back and have a set of maps at my disposal.

I would definitely have the abs system and ecu checked out.

elysium19

iTrader: (1)

I don't think there's a physical sensor; could be, but I don't know. But if the clutch is out, the car can easily know what gear you're in with just engine speed and vehicle/wheel speed. And there is a clutch sensor, so it knows that. And if the clutch is not engaged, then it assumes near zero engine load, and everything gets simple.

I'm not sure on the details, but I know the car knows what gear your in.....it wouldnt be able to create proper A/F ratios and spark timing without it.

maxxdamigz

iTrader: (1)

What gear you are in is entirely unrelated to your AFR. It's a simple matter of how much air you intake. You can run the same fuel table revving the engine in neutral, first gear, sixth, and reverse. Now, there are acceleration enrichment tables, cold enrichment tables, and other fuel tables for special fuel addition. These don't tie into what gear you are in. I don't think the engine usually cares what gear you are in for calculating fuel/timing under normal operation. The traction systems rely heavily on wheel speed input.

Hmmm. Anyone ever pull their ECU? It's pretty easy to get at. In an older car, I would suggest you just plug someone elses ECU in and see if that fixes it. Your car is under warrantee so I'd make a dealer fix it.

klepto

thanks guys

And Al I haven't driven the car w/DSC off yet. Remember i only have 6 solid months of driving stick. I mean I think I won't have issues but better safe than sorry until I have a lil more experiance under my belt in a $30k car...

CnnmnSchnpps

iTrader: (1)

dude the world isn't gonna explode if you drive the car with DSC off; esp going 80 in 6th you won't have enough torque to get into trouble. at this point that is the first thing i would try - can you reproduce the problem with the DSC off completely

to correct some of the other misinformation floating around:
- the car does not have a "what gear am i in" sensor; there are however three switches in the driveline that the ECU can see:
* clutch
* neutral
* reverse
(hence my earlier questions about does it happen when you are in/out of gear, or just clutched in etc)

- the ECU could theoretically calculate what gear you are in based off RPM and wheel speed; however i doubt it does this since this would cause issues with different tire circumf. (even just with normal wear), different diff ratios, etc

- on a MAF based system the engine load is a function of RPM and MAF reading

Some suggestions for further troubleshooting:
* turn off DSC and try to reproduce the problem
* if problem persists with DSC off, try to make it happen slowly, separating "lift off gas", "clutch in", "gear out", "clutch out", "brake" into discrete events and see what triggers it to stall

I have a hunch that this is related to DSC...

--edit--

oh and post a link to this thread in the issues and problems forum, you'll get lots more input.. some of it might even be good

klepto

thanks will have to try it all.

klepto

actually I did...I got way more constructive info here than in the Tech/problems section.

CnnmnSchnpps

iTrader: (1)

well, i did say "might" ... there was a small chance

klepto

you are right on that my friend...lol

alz0rz

iTrader: (41)

I should add Jeff that DSC is there only as a safety buffer. It only comes on when it needs too. If you don't feel it come on while your drivig normally or see the icon blink on the dashboard then turning it off should do nothing for your driving style, you won't even know its off.

alz0rz

iTrader: (41)

Regarding the ecu knowing what gear you're in, I say that because Ive seen/read certain OBDII diagnostic utilities display it. I'm sure there is no physical sensor but it could be extrapolated..

I'll know next week when I get my full CarPc up and running. Look for the thread I'll be running Hymee's Scanalyzer.

Ps: It sucks typing on the iPhone.

al

CnnmnSchnpps

iTrader: (1)

Some people have debated this point... Anyway, let's see what happens when Jeff tries it out

teknics

Ok first:
The rx8 PCM knows what gear you're in, it loads different maps for different gears. Story over, i can videotape the IDS system. So let's stop wasting this guys time debating if the car knows what gear its in.

Secondly, I need more info:
-Idle, shaky? no change since this began happening?
-What is NOT stock on the car? Even if you put a sticker on a window, believe me it matters (not the stickers, you know what i mean)
-This only happens in 5th and 6th gear? have you tried putting it in 5th at like 80, then just letting it roll down to like 40 and tapping the brake to see if it dies?

Now for my insight:
Off the top of my head I'm thinking vac leak, MAF sensor problem (wiring or maf itself), brake switch malfunction, etc etc.

What I would personally do first is recreate the problem, then I'd remove the brake switch from above the pedal and try to recreate the problem. If i cant recreate it with the brake switch out of the game then we know it's electrical, if it still stalls then we to the intake system for vac leaks and possible MAF malfunction.

The rx8 PCM is VERY intricate and things that you wouldnt ever imagine affecting anything will make the rx8 do backflips.

Anywho, get rid of your intake before bringing it to the dealer (once you remove the intake make sure you can still duplicate the problem), most likely whoever you bring it to is gonna call for one of mazda's regional techs to come and help figure it out, they will see your intake and drive the car outside park it and say bye bye.

and for those who are sitting there saying "oh man, the intakes dont affect the engines at all, you just work at the dealer and think just like they all do"

That's not true, it's just that i KNOW from firsthand experience how bitchy the PCM is on the rx8. If it doesnt like something it sees it bitches out instantly.

But all in all, you're probably looking at it being down for a while wherever you bring it.

I'm betting its something super simple/stupid such as the brake switch not sending the exact voltage the PCM wants to see or something.

edit: DSC is always active, as in "ready to go mode" it switches on as soon as it's combination of sensors goes barely out of preset safety specs. Is it always "on" no, in the same way that the ABS system isn't always "on" they're both just waiting for the PCM to request them and then the react as told. The car knows the exact angle of the body of the car the exact extension of each corner's suspension and more, all constantly updating, it knows when tire slippage occurs down to like the hundredth of a MPH.

You guys should learn about the cx-9 systems, as far as mazda is concerned, that truck knows EVERYTHING going on in, on and around it, at ALL times. I'm figuring the '09 rx8 will have similar abilities.

kevin.

klepto

hey kevin

Intake is out. But ihave had it on the 8 since about the 2nd week of owning the car. I now have it 6 months.

I had a catless midpipe. Took it out. tried to recreat the problem and it deffinately happened.

I swapped back the OEM air box now. Didnt get a chance to recreate the problem but my guess is that it is going to happen once again.

Basically here is the seneario. Im driving. i accelerate. I dump into 5th from 4th. Im cruising. A need to slow down for a second arises and I

- let go of gas
- press clutch
- press brake

As soon as I press the brakes the following happens

- gas shut off
- all warning lights come on

I try to

- press clutch
- put in nutral as it coasts
- holt clutch down
- attempt to restart as it is rolling

AND it does not start up it doesnt crank at all.

I coast to the shoulder come to a full stop and I restart the car and continue driving. but now I dont go past 4th gear and dont accelerate more than 65/70.

I tried to recreate the same problem in 4th gear and accomplished it around 85/90 mph. Hence why i keep it at 65/60 max mph.

I checked all the vacum hoses and everything is fine.

I check battery terminals and everything is OK.

I check the MAF and it is clean and no obstructions in the way.

I checked the fuses and they seem to be in tackt. They do not look or even smell burnt out.

I only use Super gas from reputable stations (Exxon, mobil, Amoco/BP, occationally I use Sunaco or Hess)

I never let the gas tank go below 1/4 tank of gas.

I have only 5000 miles on the car

I have done two oil changes. And I only use MAZDA oil filters.

As of right now only mods I have is Espelir Springs and a Carbing rear brace bar. I have Oil pressure and Temp & Water Temp gauges BUT THEY ARENT HOOKED UP YET. And the problem even before I mounted them on the dash. AGAIN THEY ARE NOT CONNECTED AND HAVE NO BEEN CONNECTED YET.

klepto

Also I have had the MSP 16 recall done to the car.

klepto

ALso about the oil my 1st oil chance was castrol gtx 5w20 (done @ 1500 miles)

the 2nd oil change i switched to castrol gtx 10w30 (done @ 4000 miles)

but both times has been w/ OEM spec MAZDA oil filters

klepto

Kevin

Idle is OK fine no issues. I have tried down shifting to reduce speed but it is the same out come....goes dead cant start have to come to a full stop then i can start up and go again.

What wasnt stock was my RE intake and RP midpipe (catles & resonated). I removed the mid pipe 1st. Was ABLE to recreat the issue. I just removed the intake and put back the OEM air box.

I have to pint out that I have had the RE intake in the 8 since about the 2nd week of owning the 8 and never once did I experiance any issues.

I also try to redline 1st-3rd to clear any carbon from the motor. I regularly check the oil and radiator fluids. The battery is pretty much new but now I have an Optima battery. I no longer have the OEM. But the optima is less than a month old (combined with previous owner (Chrism) and myself).

In terms of engine exhaust that is all I have done. Suspension is done but I HIGHLY DOUBT we can blame that for the issues.

Other than that i havent done any electrical work on the car or mechanical work onthe car. I do have gauges as stated befoe but they havent been wired yet. So we cant blame it onthat and besides the issues started before I even installed the pod w/the gauges on the dash.

Now if the dealer wants to be silly about a lil engine paint and a banner on my windshiled I'll gladly bend over and let them SUCK MY *** HOLE as I FART....cause lets be real we all know that is not the cause of whats going on. OH and I own a JDM badge from Japan that I waited 2 months for on the rear trunk....

CnnmnSchnpps

iTrader: (1)

Cool thanks for confirming that. I'd really like to know what it uses that information for..

You get the same issue if you try to downshift without hitting the brakes?

Revvittupp

He said it later... the ECU has different maps for each gear. I remember reading that in the Cobb AP discussion as well.