Rx8 Dave

In addition to what ken-x8 wrote, my 2 (or more) ¢ :
......You should NEVER disconnect the positive without DISCONNECTING the NEGATIVE on a battery FIRST. Otherwise you could short the battery and even the ECU. RECONNECT the battery terminals POSITIVE FIRST, then negative, ALWAYS in that order.
......Replacement: AGM is the kind without the vents on it. They take high voltage and do better on the RX8s but are usually more expensive because they are sealed. Personally I recommend going with a "low resistance" battery because it will increase your starting power on the 8. This can be noted by high cranking amps. Get the highest you can. Do not buy/use Optima battery.
......NOTE: Disconnecting the battery clears your fuel trims, and can mean idle instability as a result. It might be not really noticeable (I never noticed it on mine). Drive alot, and they will reset themselves eventually. If you need to reset the ECU / NVRAM (Clearing the eccentric shaft plate profile) for 2004-08: Engine off, key position to ignition ON. Do 20 pumps of the brake petal within 8 seconds after the ignition switch is turned ON [you will see the oil pressure gauge needle will move to right of center slightly (nearer H)(some older models, like some '04, the needle does not move)] confirming the operation has been completed. After this, turn the key to the off position, wait at least 30 seconds, then you can start the car.

Chrishoky

iTrader: (9)

Thank you thank you thank you. I knew about most of these notes but its always nice to have the reassurance. I know to always disconnect negative first the positive, and install in reverse order. The battery available closest to me with the best cranking amps is an optima red top with 720 cca, but its close to $220. Im thinking of just sticking with OEM one, its 620 cca, but its $120. Thoughts?

Littutor

A note to add. . .my husband replaced my battery and my car died at every stop on the way to and back from town. Apparently the car had to "relearn" the fuel injection mixture. Once learned, it hasn't happened since. Littutor

RIWWP

iTrader: (2)

^ Correct. That's common. You can bypass most of that issue by letting the car idle for 10 minutes before driving it the first time after a disconnect. It will re-learn the idle trims much more accurately, and reduce the risk of stalling while trying to return to idle from higher rpm driving.

Chrishoky

iTrader: (9)

I have experienced this issue before when I have disconnected the battery for other maintenance. Thanks everyone for the advice!

Rx8 Dave

You're most welcome. I would avoid the Optima and go with the OEM @ $120. If you keep your ignition maintained (coils, plugs, wires) 620 cca should be fine unless you move nearer to the Artic Circle.

Rx8 Dave

I'd certainly would get proof it's the ECU, not coils, plugs, wires, etc., etc. I've seen RX8 ECU's NEW from $400 - $1000 US (£252 - £629) depending on the unit (plus the refundable core charge). Search around starting with Engine Control Module/Control Modules for 2004 Mazda RX-8 (those are for an '04, but you can put in your model) make sure you have the unit's correct serial # and search around the Internet. Cheers and Good Luck

Rx8 Dave

Aston - even if it's a light knock, check under MIAC threads including https://www.rx8club.com/rx-8-discuss...-miac-181950/:)

Rx8 Dave

Jazzmeson - I'd try adjusting the clutch first. There are threads debating adjusting the PPF - from if it's fitting over the bolts it's OK, to needs to be to specs (52mm). In any event, it's safer, of course, to put it back to spec, but some wouldn't think your 2 tenths will ruin the drivetrain until you fix it. Personally, I'd bring it to spec ASAP.

Jazzmeson

iTrader: (5)

Thanks for the help. I slightly raised the transmission and re-torqued the front power plant frame bolts today to spec of barely past 2". I noticed just slightly less NVH, not significant but the difference is there for sure.

As for the clutch pedal... I pumped it for a brief amount of time and it has gotten better in terms of firmness and the engagement point raised as well. There really might be air in the master cylinder after all, but I'm going to attempt to inspect the pedal and adjust it anyway just in case it's out of spec as well.

Thanks a lot for your input.

badinfluence

Does anyone know what the Mazda OEM Alternator is supposed to produce voltage wise? In my speed it was more like 14 volts rather than just 13.5. (Taking battery load out of it)

Also does any one know what the ECU's limits are for it's DC to DC converter? (Max Voltage it can tolerate?)

I want to up the battery voltage a bit and see if it makes a difference on the starter or a voltage drop I seem to be having with the OEM HIDs. They seem to draw way to much power.

kallenthe8

Hey guys ... I have just enough money on hand 2 pick 1 of the 2 .... A BHR ignition kit ... Or a Cobb accesport and a tune ... Wich would u get and y... I can't decide on my own need convincing

BigCajun

iTrader: (1)

BHR ignition.
Just installed mine along with plugs, air filter, MAF & ESS cleaning and runs noticeably better.
Plug & play, forget about tuneups for awhile.
Can't say that about the Cobb.

badinfluence

I asked my question because I want to go with a BHR myself, and exchange the battery for a Maxwell Supercap and relocate the battery to the trunk. Higher Voltage = better ignition. Lower voltage = more amperage = parts wear out quicker.

I think if we can just increase the voltage a bit on our cars, it might prolong ignition coils and give us a bit of a boost at the pump.

Rx8 Dave

Glad to help and that you're on your way to resolving the problem.

Rx8 Dave

badinfluence: [Quote]Does anyone know what the Mazda OEM Alternator is supposed to produce voltage wise? In my speed it was more like 14 volts rather than just 13.5. (Taking battery load out of it)

Also does any one know what the ECU's limits are for it's DC to DC converter? (Max Voltage it can tolerate?)[quote/]

I don't know the ECU limits, but would think under 15 volts would be it.
For the alternator, the shop manual says 13 to 15 volts UNDER LOAD is OK, but I think 13.7 to 14.5 volts is a better range, 13 volts seems a bit low to me. Some say the voltage should be 14.4. I think if you're at or above 15 volts you'll overcharge the battery and will eventually kill it. If you can't check under load, leave all the headlights on for about 20 minutes then check the battery. Your problem may be the battery, a bad cell, etc.

badinfluence

[QUOTE=Rx8 Dave;4635931]badinfluence: It isn't really a problem, I just don't want to cook the ECU when I remove the battery. Our cars MUST have some kind of load on them or the Alternator will kill itself, so any battery store that removes the positive terminal while the car is running could blow up your ECU and alternator. I had a professional alternator builder tell me that.

My supercap would allow the voltage to get higher without damaging anything is my idea. 12.7 is normal for a AGM battery, and it takes 13.5 volts to properly charge a 12v battery. A 12 volt battery is dead at 12 volts technically. Mazdas run higher voltages so I was thinking if I could get that up to 15 it might save some ignition coils.

badinfluence

Anyone got an advise on the R3 tire pressure? I am running Mayrun 500 tires (I didn't pick them ugg), and they go up to 59 psi for some reason. I was wondering what you R3 guys keep your tire pressures are in the front and the rear and maybe elaborate on the differences between lower on the rear and higher.

I am running 40 in the front and 42 in the back, and the car drags less. The shop that replaced 2 of my rims put everything at 29psi for some reason and it makes the car bumpy, feel like ****, and slip when you DON'T want it to.

gwilliams6

Most RX8 tires are right at 32 psi for street use. Dont know these Mayrun tires, so i suggest you go online and track down the recommended pressure. There is no street tire I know that runs ANYTHING near 59psi, ever.

Signal 2

Not an authority on tires, but 59 psi is probably max pressure cold. NOT a suggestion for optimal pressure. That's going to based on factors like weight/load, conditions, tire structure, compound etc.
I'm guessing those are all seasons. So if you don't like them or intend to replace them with something more performance oriented, while keeping it safe, I think I'd just go where they feel the best given the conditions and your driving habits, even if wear is accelerated or uneven. Know that mileage may suffer too.

RIWWP

iTrader: (2)

59psi is probably just the maximum possible PSI before it will explode from the pressure. You never want to get anywhere near the max, because hitting something hard like a pothole will temporarily spike the pressure much higher.

The RX-8 does best between 29psi and 34psi. You can go higher for better gas mileage (and lower grip), but it really isn't recommended. My 2005 would pop the TPMS light if the pressures got below 28, or above 35.

ken-x8

The reason they did that is because shops never set tire pressures correctly. The most common problem with new tires is after they inflate to 40 or 50 psi to seat the bead they don't bleed off the excess. The most common problem overall is that when they do try to set the right pressure it's the lowest guy on the totem pole, who doesn't give a s*** about what he sets them to.

I check tire pressure every few weeks, after the car sits overnight. Very frustrating when I need to re-do that after every oil change.

Ken

gwilliams6

Did a quick online check and yes these tires are all-season tires. Correct Tire pressure will vary from car to car (even with the same tire) due to suspension loading and handling requirements of each car . But as a rule all RX8 tires for street use should be around 32 psi. You could change this for track use or when you are carrying a different than normal load and road conditions warrant more or less pressure.

poacherinthezoo

59 psi is very high for an all season tire, to the point that it makes me suspicious of the measurement. Are you measuring the pressure with one of those $0.99 crack-pipe (pen) style pressure gauges? I don't trust those things, and have gotten wildly inconsistent readings with them. I would suggest comparing the cold pressures between your current tire pressure gauge and another one.

The driver's side door jam has the recommended pressure. For the R3 it's 32 psi (cold) all around.

Other things to consider are if the tires are not the same size as stock (225/40R19), and if they have they accumulated enough miles to show any uneven wear patterns?


In my R3 I keep the tires at 32 psi front and rear for street use.

Aston177

Page was not found. I'm starting to think it's not a knock. It's not as loud as MIAC. I'm guessing it's the SSV rattling under load. My SSV ticks at idle when the RPM drops.