Outlawed Piper

First of all, I'm new to this forum so hi. I bought a mt 2004 RX-8 this June at 39,000 miles. I had a CEL P06-something that the cause was a faulty PCM, so eventually I got around to getting a new PCM from Flagship 1 for my car. I just had the PCM installed and the keys programmed to the new PCM at the Mazda dealer (as well as them breaking open my driver door lol) and I left the dealership, happy to see the CEL gone and Cruise finally working. I then revved it after my engine warmed up and a new light came on, but it flashed occasionally too, which obviously concerns me. I got the codes and they are P0300 and P0302, engine misfire codes. The thing is, a couple months ago I already got new BHR coils and wires and new NGK spark plugs, so I don't think it's caused by the usual problems? This is what I need help with. Is it the new PCM? Is something else wrong? I don't want to dump a bunch of money into an easy fix but I don't know the move to make. Any help is appreciated. Thank you

Loki

iTrader: (1)

What is Flagship 1? ECU failures are extreeeeeemly rare, often other problems are assumed to be ECU problems. Knowing the code you gad originally might be a clue here.

Anyway, flashing CEL is always a misfire, so if your ignition is fresh, which is good, the next stop is to check if the catalytic converter is clogged or broken up. Easy for any exhaust shop to do. Don't recommend driving the car much until you confirm it, because bad cats kill engines (and bad ignitions kill cats, so there's a chain of events here).

rx8help.com is a great resource for new owners to get up to speed on common issues and maintenance.

Outlawed Piper

Flagship 1 is a company that sells car computers. ECUs, PCMs and the like. I wanna say the old code was P0610. Had a shop (Tires Plus) confirm it was the PCM and not a wiring issue or such. That code is gone now. Cat isn't a concern since I have the BHR catless midpipe installed. Engine health is my biggest worry here.
I've done probably hundreds of hours of reading about my 8 and a whole bunch of other stuff but I'll give that a read too, thanks.

Loki

iTrader: (1)

You might want a compression test given that the car is newish to you, just to know where you stand.

What intake do you have? Aftermarket intakes like K&N on these cars are known to cause problems like this because they don't properly straighten airflow for the MAF. The original intake is hard to improve on.

Outlawed Piper

Yeah I really should. It's not a reason not to get a compression test, but my engine has mostly been running wonderfully.
I have the AEM cold air intake (same as Mazdaspeed but cheaper if I'm correct). Cleaned the MAF when I installed that.
Also RX-8 help has been helpful. Just tried the brake stomp to reset the NVRAM and I didn't get any flashing CEL after driving. Think I'll clear the code and see if it comes back up as I'm driving it or if that did the trick. I'll keep you updated but in the meanwhile any further advice is greatly appreciated.

Loki

iTrader: (1)

Sounds good! AEM/MS is one of the good ones. The other is RacingBeat, any other aftermarket intake is a downgrade.

Outlawed Piper

So I've heard. There are very few RX-8s up here so all my knowledge and advice I have I've gained through these forums. That's why I got all the BHR stuff and such. But yeah I just spent 1200 fixing the door and having PCM installed and last thing I need right now is to dump even more money into this new problem.
Also for compression test do you figure it'd be smarter to have dealership do it or just buy a rotary compression tester and save money in the long run?

Loki

iTrader: (1)

A rotary shop is probably best, if you go to the dealer make sure they actually have a working rotary tester. If they do, great. I built one using a DIY here, so I can do an annual self-inspection of the car.

Outlawed Piper

Closest rotary shop is three states away, so that's not really viable. I guess I'm not sure if any of the local dealerships do I should ask. How did you build your tester?

Loki

iTrader: (1)

https://www.rx8club.com/series-i-do-...%24100-261310/

There's another version on instructables.com

Outlawed Piper

Interesting. While that looks a lot cheaper seems to complicated for me at the moment.
So I don't think I've had any more misfires since clearing the CEL, as the CEL hasn't flashed since I've reset the NVRAM. Then something possibly worse happened right before I got home today. I was driving and all the sudden my car seemed to restart as though I had started the car for the first time. Radio reset, all the dash lights went on, traction control was really funky as it tried to make me spin out when I was going straight. Restarted the car for real and it didn't happen again for the last minute getting home. I'll have to see if it does this tomorrow. I swear with my car I solve one problem and another shows up

Loki

iTrader: (1)

Sounds like a loose battery cable.

Outlawed Piper

I'll check it out and try resecuring them in the morning. Maybe that was contributing to the misfiring too. Do they just come loose from vibrations over time?

Loki

iTrader: (1)

Not supposed to, but on any car the clamps can stretch over time and with repeated lossening and tightening. Might be good to replace them, but just make sure the contacts are clean and the clamps can't wiggle or turn on the post, and there's plenty of contact surface.

Outlawed Piper

Checked the battery this morning. Both clamps were too tight for me to pull on or move at all without a tool, so I left them. Then went I went to start the car, DSC OFF was flashing and the Traction Control light stayed on. I looked this up on the forums and saw it means you need to turn the steering wheel all the way to the right then the left to reset it or something after the battery is unplugged. So while battery was never unplugged must be related to battery. Had no issues since thus far

kevinande

Any update? Sounds like the battery may need to be replaced.

Outlawed Piper

Yeah sorry I've been busy with finals. Was going fine after last update no CELs until yesterday sometime after getting a car wash I got another CEL. Checked and it was a P0103, for MAF sensor high voltage or something like that. Checked these forums and other guys had a similar problem. Nothing too bad except engine retarded at higher rpms to prevent misfire (which it did once but didn't give me the P0300 and didn't misfire again). This morning when I started the car it was gone though. Then later it made me do the battery reset thing when I started the car again, so I did that and since still ran fine. Though I did find after doing that while on the freeway went to use cruise and it didn't work. CRUISE MAIN was on but it didn't set a speed so that was weird but that works again too so honestly I don't have a clue. Brand new battery this summer right after getting the car so can't imagine it's that, but it's definitely gotta be something battery or connection related. Maybe dealership didn't reconnect something good enough idk. So currently still no CELs, good mpgs and power so I'm just going with it. This has been a crazy forum thus far but thanks for helping out. I'll give updates when another thing inevitably goes wrong.

kevinande

I would still have the battery checked just to rule it out. It does not take long to ruin a battery under the right conditions. Cars loaded with electronics and a sub par battery causes weird things to happen.

Outlawed Piper

Sorry it's been a while. You guys were right, I ended up needing a new battery later last January. I'm having a different problem but same two codes so I figured I could just keep using this thread. After driving long periods of time at interstate speeds (85 mph, 4250 rpm), sometimes I start losing power and fuel economy tanks. Seemingly irrelevant, after driving a bit, especially spirited driving, sometimes my car stops revving past 6-7 k, obviously being retarded by the ecu, and I finally got it to give me these codes to confirm. I think the problem this time is fuel pump, as it would make sense that it overheats after running 4k+ rpm for hours unending and doesn't make enough fuel pressure at high load and rpm for redline pulls. Just wanted to hear your thoughts or recommendations if I'm missing something, as well as an aftermarket fuel pump suggestion. (I had fuel starvation issues this spring where car would randomly stall when fuel pump overheated, and just replaced with oem pump. I've now read it wears down super quickly and the conditions I've put it through haven't helped). Please don't kill me on the fuel pump question BHR doesn't sell a fuel pump anymore and I can't figure out which fuel pump was good there was so much said about walbhro, bosche, denso, and 09 but nothing ultimately conclusive just lots of debate so I was confused so any suggestions now that it's much later would be greatly appreciated.