05 RX-8 weird issue with redlining
 

Hello all!

I purchased this car because it said it needs a new engine and doesn't start... well I had it started in less than 5 minutes of it being parked in my garage... Kind of mad because I really wanted to tear down this engine and rebuild it. The car off the tow truck had a battery light on the dash when running, showing 13v... The battery was barley a year old, so that's not it. I replaced the alternator, and started it up and the battery light went away. Mine you, I test drove the car before I changed the alternator. But I did replace the spark plug wires, spark plugs and oil because the car has 119k miles on it and figured I'd do a 120k mile tune up. On the test drive, I did redline it and it drove fine. Noticed it needed new engine mounts. But other than that car is f'n mint.

Replaced the alternator with a random non branded alternator from eBay. Hahhahahah..... yeah..... well, the battery light went away. So at first I was happy. But when I redlined it in park the traction control light, abs light, brake light and power steering light all came on (The redline beep did not make a sound with this alternator). I broke out the multimeter and checked what was going on. And found that the "new" alternators voltage regulator was clearly not doing it's job, it was allowing the voltage to jump to 17v at redline...Returned that one and got another one from Amazon. This time it didn't have the lights freak out while in park. But when driving and you redlined it, those lights would pop on. Is this car that picky when it comes to what alternator it has in it? I have a genuine used 40k mile alternator on the way, so I'm hoping that remedies this annoying issue. Only other thing I can think of that would cause this, would be the grounds to the engine should be refreshed. Or that the first replacement alternator that jumped to 17v fucked up the ecu. Just doesn't make any sense because the alternator that I got the car with didn't do this. It's now gone through two new alternators either being trash on arrival or the first one caused more problems. I'm hoping this genuine alternator stops this weird problem.

Does anyone have a diagram of where all the grounds are for the 05 RX-8? I can't seem to find anything on this vehicle when it comes to this.


Thanks!!

No real common issues with alternators... OEM is best, but voltage regulation isn't rocket science. Are you replacing the voltage regulator with the alternator?

Have a read at rx8help.com to avoid other issues. You did the spark plugs and wires, you'll want to do coils, they're the biggest risk on any rx8.

FWIW I have had zero luck with auto parts from Amazon with an unknown name brand. 2 dead starters and an alternator that would dead short as soon as battery connected. No more for me, even on a low usage low value vehicle.

Also I heard a surprising story from a good friend on a 09 or so 4Runner. Bad alternator after over 300k miles. Alternator replacement threw all kinds of codes, tried 2 different brands of good ones known to shop. Fixed with OEM Toyota. This was just this year. There’s probably some bad electronics running around right now, like the Chinese capacitor thing 20 years ago.Everything from Dell computers to GE fridges was affected.
Killed Mitsubishi as a TV manufacturer also. Class action, etc.

I mainly work on Toyota's and their known to be picky with certain genuine OEM parts. Especially their older trucks, they hate non OEM starters and will tear right through any other brand, reason I asked about this car because it's looking to being the same way with this car. You'd think brand new alternators would have working voltage regulators lol... Guess not. What is the OE alternator brand for this car?

Our voltage is regulated by the PCM instead of the voltage regulator.
The ISO 16750-2 test will supply 24v to a 12v electrical system for 60s to simulate a double jump start situation, 17v should be fine, but not recommend to continue driving.

Genuine used alternator fixed the issue with the electrical system shutting down while driving. Problem solved and created a new issue with the car randomly dying at idle when hot. Hopefully the idle relearn procedure cures this. Other then that, car runs and shifts normally.

Great. Is the intake stock? Any OBD codes? If it doesn't learn to not stall, look for vacuum leaks. You can check fuel trims on a warm idle to see if it's getting unmetered air. I take it restarts easily?

Everything is stock on this car except for the shocks, they upgraded to KYB struts. Other than that, it's stock. As soon as I started on it I removed the intake and found that there was oil on the filter and all over the MAF. Cleaned/replaced those, changed the ice tray looking cab filters. Cleaned the throttle body from all the buildup. Replaced the wires and spark plugs and changed the oil and got a wix oil filter for it since the oil literally looked like diesel. Who ever had this car before me didn't take care of this car or knew about needing to change the oil frequently. Surprisingly enough the trans fluid is clean. Rear diff probably needs a drain and fill.

The car starts no problem when it's cold. But when it's hot, it takes about 2-3 seconds to start. So it's safe to say these apex seals need replacing. I think the procedure is the ticket, because when I first got it and I never removed the battery. It idled just fine even when hot. So I don't believe there are any vacuum leaks on this car. I stole this thing for $1,300 because they couldn't get it to start so they assumed the entire engine was trash.

When I was dealing with the stupid china alternators. I was getting an intermittent CEL with the secondary air pump that would come and go. I took the connector off and cleaned the little rods, never had the code come back. So far no codes at all since I replaced with a genuine alternator.

https://cimg0.ibsrv.net/gimg/www.rx8...2704299a93.jpg
(05 Mazda RX-8 AT) Picture taken right after I detailed it.

Wow... after the procedure right after killing it after waiting the 20 minutes of idling. It started up in about a second or less. Whereas before it took 2-3 seconds before. We'll see if this continues to be the case when I get back from driving it when I have more time to mess around with this car. Still curious to see what the compression numbers are, sucks I can't just use my standard compression tool on this to get an accurate read. Called Mazda and they want $160 to do a compression test... Might as well just buy the f'n tool and have unlimited tests lololol..