mtourne

Hi All,

I've had some problem with my RX-8 stalling when coming to a full stop lately.
(Strangely everything started after the 60,000 miles service at Mazda...)

The spark plugs are new, I got the coils changed and I just changed the battery (group 26R it doesn't seem very powerfull)
The last thing that could be bad is the alternator. To test it I tried to start the car on the battery and remove one of the prongs.
The car stays idle and doesn't stall. But if I rev the engine and let it go back to idle it stalls.
Does that mean the alternator could be bad, should I try with a voltmeter ?
And how do you that with a voltmeter, it has to read 14v at the battery prongs when the engine is idling ?

Please help, I'm a complete noob and I've got only problems since I got this car a month ago

nycgps

iTrader: (1)

Group 26R? why ? Dealership sold it to you? if yes, bring it back and say you need Group 35R.

and your issue, it sound like either bad engine, or your TB is bad.

rx8cited

Group 35 (no R)

nycgps

iTrader: (1)

There are Group 35 battery with Terminals in the middle of the battery.

You need 35R, so the terminals will be at the "right spot"

rx8cited

Do you have one in you car or pictures or can find one on the internet? Two sites I checked say group 35 for an RX8.

Razz1

The car stays idle and doesn't stall. But if I rev the engine and let it go back to idle it stalls.

This is common when the battery is disconnected.

The ECU is relearning.

After a few drive cycles it will be fine.

Just look at your battery.

nycgps

iTrader: (1)

Most internet site would not tell you its a 35R, probably to avoid confusion.

Take SummitRacing for example. on the site it tells ya nothing about the 35R part. but when you get the battery, you will see it.

I did NOT get the 35R cuz my stock battery just died on me on a good morning and I need my car right away, so I ran for an Optima 35 with terminals in the middle. it doesnt fit so I have to buy another extension for the positive terminal. (negative will work, its long enough)

mtourne

I bought the battery from NAPA.
Apparently in the auto parts shops, if you tell them you have an 04 RX-8 they will give you a 26R (which was the stock I had).
For later model their database shows up with group 35 only.
I can't find any store that has the Optima 35 in the bay area, plus they will charge me a 15% restocking fee if I bring back the 26R.

nycgps

iTrader: (1)

Yes, its hard to find Optima 35R. most shops dont even know that they existed. when you tell them you want a Group 35R, they will give you the Group 35 and say "This is the only thing that Optima makes for Group 35".

well, if it the 26 fits perfectly fine, its all good.

Just make sure it has enough CCA. 650+ preferred.

mtourne

I think it's closer to 500 CCA, would I have better starts with a 650+ CCA battery ?

And what do you guys think about the DieHard 35 Platinum that SEARS sells ? Isn't 50lbs heavy ?

Charles R. Hill

iTrader: (7)

I agree with Jackson as Kevin (teknics) has written a bit lately about "idle air control" problems in the throttle body. This should be covered under warranty, IIRC(?).

mtourne

Hmm I'm quite a noob, what's a TB ?

mtourne

I've read teknics's thread about the IAC, in it they say that stalling might be the result of a pcm reset.
My PCM was upgraded at the same time they performed the service at Mazda, so the stalling might be normal.
I haven't experienced any stalling with the car so far with the battery replacement.
Still, how do you make sure the alternator really charges the battery ?

Charles R. Hill

iTrader: (7)

Place a voltage tester across the battery terminals and see what your voltage is. Start the car and see if the voltage goes up. Then, turn on your headlights and a bunch of other accessories and make sure the voltage stays the same.

nycgps

iTrader: (1)

500 is kinda under powered. it should be ok if your local climate is not that cold. but getting something above 600+ is ideal.

That one doesnt look that bad. Sears is everywhere and 4 yrs replacement is a + for our cars. but what are you going to do with your 26 ?

So you know what TB is by now.

Your car COULD stall if you just unplug your battery, it needs to re-learn. but my old motor used to stall after I unplug my battery. and now, I just unplug my battery couple days ago, car never stalled. So in my opinion, a "good" motor shouldn't stall under any circumstances. Thats just my opinion tho.

mtourne

I still don't know what TB stands for though
Is that part dealer only ?

Charles R. Hill

iTrader: (7)

TB= throttle body.

nycgps

iTrader: (1)

is the silver looking thing that sits between your plastic intake and your plastic intake manifold.

EDZRIDE

iTrader: (1)

There is no Group 35R battery. If the terminals are in the "middle" of the battery, then it's considered a Group 75/35. See the 2nd picture, post 33 in the link below:
https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/optima-red-top-batteries-151027/page2/

mtourne

I read a lot about TB / Air intake, and I'm considering mounting an oil catch can. That looks DIYable even for me

Is there a way to see if my TB is clogged with oil and how to cleaning it ? Do I need to remove it to do so ?
I haven't found any DIY forum thread about cleaning the Throttle Body.

Edit: typos

EDZRIDE

iTrader: (1)

Yes you need the higher amperage battery; the DieHard 35 Platinum is an excellent choice.

rled

Your car would only stall and die if both your battery and alternator aint doing their job. If your alternator is working correctly the car will run even if your battery is bad . It just won't start back if it dies or you turn it off. Also, if your battery is fully charged, the car will run even if the alternator is not charging until the battery voltage drops below approximately 12volts.

nycgps

iTrader: (1)

Thats my battery.

Maybe I got it wrong. blah.

Anyway to OP. Get something stronger.

and you cant really clean your TB. all you can do is replace it. couple hundred bux part.

rx8cited

So you got a back assward group 75/35 instead of a group 35 I think your confusion is that you wanted a reversed group 75/35, which would make it a group 35.

To remove any doubt out of our minds, here is the diagram for an Optima group 35 - no "terminals in the middle" like you eluded to.

nycgps

iTrader: (1)

if I remember correctly. Someone here did get the Group 35 but it still doesnt fit. the terminal is still a bit too far and need an extension.