micvite

So, I just bought my rx-8 the other day, drove it 3k miles in 2 days with nearly no problems, except it feels sluggish, and if I'm flooring it at WOT it falls on its nose at 7-8k rpm and will start bucking and flashing the CEL, now if I let up off the throttle to where it's like 1/8-1/4 throttle it will rev up to red line just fine, but slowly. Also in neutral car revs no problem. What could be causing this? Engine was redone under warranty last year (5k before I bought the car so 8k total and nearly may 2017 for engine, mazda doesnt know if it was new or reman but the compression numbers are fairly low (7.2-3-2 and 7.6-5-4 and I don't know the rpms). After trying to see if redlining for a while (a few times a trip) would help with anything now I'm getting P2004 and P2005 CEL which are the intake manifold runners stuck open (not sure if that's a horrible thing or not but obviously cant be good haha). I tried resetting the memory (disconnect negative battery brake stomp and do the relearns and CEL went away for a few shorter trips until I tried to redline it again just now and it came back (so I'm guessing they did close at some point or the computer doesnt test for it until after 8k rpm? Or maybe the misfire screws something up? Anyhow any help would be appreciated so I can figure out how much itll cost when I get my oil change tomorrow. P.S. the car vibrates horribly at idle, no change in rpm just bad vibration. If I rev up ever so slightly it goes away until it settles back to around 800-900 for idle . 69k on car as a whole and I'm trying to find out tomorrow about plugs coils and wires and hopefully I can have the dealer unbolt the cat real quick during the oil change to see if it's clogged. If this matters, I was cruising at 100-115 (5-6k rpm)on the trip home car will not go over 120 unless it's a steep downhill slope.

Loki

iTrader: (1)

Coils, plugs and cat inspection are the correct next steps. Sounds like the cat and unfortunately, if that's the case, the hard miles you just put on it didn't do your compression any favours.

Google "flashing cel rx8".

The intake manifold runner codes are relatively common, you can google them too. The 3 intake valves open in sequence at different rpm points and are all open by 8k. Unfortunately they get gunked with oil from the pcv. If the engine is newish this is a bit surprising, I would hope someone would have cleaned them while the engine was apart. Narrow down which valve it is and see if you can clean it. The most common one is the SSV.

Since you just bought the car, what does the previous owner have to say about this?


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micvite

Well I'm hoping it didn't do too much damage, honestly with the engine being that new the compression is horrible imo, was expecting at least 9s haha. To diagnose which valve it is, I have to basically tear the engine bay apart don't i? and I dont have the tools so I'm hoping there is an easier way to get to the other valves (aside from the Ssv all the way in the back) my question is, why does the valve only stick after 8k rpm during wot (partial throttle no cel after reset, but instant cel at wot)

I bought it at an audi dealership, previous owners traded it in for an audi, apparently were an older couple in their 60s. So I don't know much about the car other than the mazda warranty engine. (The reason i bought it in the first place) would mazda do anything for me if the engine is already failing after 5k? Assuming that the 7 compression was at 330 rpm?

mazdaverx7

iTrader: (6)

The APV motor may not be able to rotate the auxiliary port vales fully open due to carbon buildup. This is common and can cause a misfire and low power after 6250 rpm. I had this happen to me once. The down side is that the engine will need to be pulled to remove the lower intake manifold. The auxiliary ports, the linkage, and intake manifold will need to be cleaned thoroughly before re-installation. The variable intake valve opens at 7250 rpm and may be sticking as well. The secondary shutter valve should also be removed and cleaned and the gasket should be replaced when doing so. The intake setup on these cars is responsible for high rpm power delivery and negates the need for a dynamic chamber, which was used on the early fuel injected rotary engines.

With that said, you will also need to replace your spark plugs, wires, and coils as preventative maintenance. The coils are known to fail and cause misfires. I just replace everything as a package. You could also get a BHR ignition coil setup and forget about the coils for some time. I have them on my BB 04 and they are fantastic.

Loki

iTrader: (1)

The compression numbers are passing if those numbers are at 250 rpm. If they're at a lower rpm, that's even better. Borderline if at 300rpm. What year is the car and does it have the updated starter?

​​​​​​Don't expect "at least 9s", the engines leave the factory with 8.5 @ 250. This is what they're designed to be.
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BigCajun

iTrader: (1)

You need to get the catalytic converter inspected ASAP.
You can do more damage to your engine if it's bad.
Dealership could've dropped a reman in there without diagnosing what caused the last engine to fail.

Misfires kill cats, bad cats kill engines.

micvite

Ok, thanks for the info! Do you guys recommend the stealership for the cleaning of all the valves? Or is an independant shop better (have one that's around 100 miles away up in north jersey, I'm near Atlantic city) I have an 09 so I'm pretty sure it's the updated starter, no hot start issues, fires up instantly, like not even 1 crank, you turn the key and it's running. (I called the dealership where they did the compression and they said it leaves the factory with 10 lol.... sorry if I'm being a noob) For the time being if I drive under 6-7k rpm after doing the ignition and inspecting the cat assuming it is the valves would I be ok? Also just wondering why would the valves cause a misfire at wot? I mean assuming they're sticking open like the code says, shouldn't it be just fine since they're supposed to be open at high rpm and high load? Now assuming they're all closed wouldn't I just have abysmal power and the computer would compensate for less air with less fuel? (I'm guessing that's what happens at part throttle which is when I can actually rev all the way and why I'm assuming it's the cat causing the air to not be able to leave the engine rather than something not letting it go in). Sorry if I'm asking fairly simple questions, I did read a lot about rosaries and the 8 in general but I just want to be 100% sure on everything (I know a decent amount about cars, even built one with a friend a few years ago, but hey I've never had to deal with a dorito sandwich powered car before haha)

BigCajun

iTrader: (1)

Every little bit helps!

micvite

Well after driving for a bit the cel for the runners went away so I'm guessing they managed to close at some point? I'm going to see about the cat and ignition soon and then figure out the valves later (I'm strapped on cash, the car was 9k after taxes and fees plus the trip to get it was around 1-1.5k) btw if the engine does check out considering no rust and 1 owner car do you guys think it was worth the price? I bought it at 65k miles.

UnknownJinX

Which trim is it? Do you have cloth, leather or Recaro seats?

But anyway, yeah, change out the ignition components and inspect the cat ASAP.

micvite

did my signature not save? It's an 09 rx8 gt manual transmission silver in color, leather seats, upgraded sound, moon roof, sirius, only option it doesnt have is the nav from what I can tell. Oh, is it normal the the car to buck a bit at low rpm when getting back on the throttle? Like say 2k rpm in second the car jerks a bit when you give it light throttle. I'm assuming the whining from what I think is the transmission is normal. (Very pronounced in first gear)

UnknownJinX

Mobile doesn't show it, not your fault.

Your price doesn't seem too bad if it is a Series 2 from 2009.

Navigation is pretty useless. I have it and the last update available was in 2014. Much better off just using your phone or an aftermarket unit.

I don't get a very pronounced jerk in 2nd gear. I do have a 1st gear whine when I decelerate, and an almost unnoticeable(you really have to listen to hear it) whine in 4th, but otherwise it's pretty quiet.

micvite

yeah it's a series 2 with an engine just put into it which is why I though of getting it. (Also inside and out the car is immaculate) yeah, i thought so haha i typically just use my phone anyway for the music too. Hmm i wouldn't say necessarily that the jerk is horriblly pronounced but it feels and sounds like a racecar with straight cut gears, also in slow traffic(under 10 mph) if I'm slowing down in first gear the car bucks and kicks like crazy until I push the clutch in and take it out of gear.

Loki

iTrader: (1)

The car is pretty high strung, this all sounds normal. Yes it will be jerky at 2k. You'll get smoother with time and maybe try to shift later so you're not driving in that range. This isn't a diesel

Whining from the trans... I mean. Some whining is normal, but it shouldn't be obnoxious.

Good that the valve codes went away, perhaps they just needed a workout. However, you really don't want to ignore cat and ignition health. The previous engine died for a reason, you really want to make sure that reason isn't in the car. Don't assume anything. For the engine to go at 65k on series 2 car is a bit unusual.

Some of the things you say give me cause for concern (uneven idle, shaking, misfires at high rpm). The valves couldcause misfires, but catalytic converter damage WILL cause misfires, so worry about the valves after you've eliminated the possibility it's the cat/coils.

UnknownJinX

Actually, I checked the desktop site and your signature still isn't showing. I think there might be a post number you have to reach to have it.

As for your last point, every manual trans car will do that if your speed is too low in 1st gear.

This car loves high revs... with everything else healthy. Fix your ignition and cat, then give it an Italian tune-up.

micvite

the only time I do drive at 2k is in slow traffic, I try not to shift to first because that's even jerkier and also you can feel and hear the poor little syncros trying to do their job. The valve codes show up after the misfire and then go away if I stay under 8k. Obviously, I'm getting an oil change now and hopefully tomorrow I'm going to take the cat off and just scrap it for a mid pipe (would straight piping that part be ok? Or should I actually invest in like a racing beat or Ap mid pipe? Again, thanks for all the help everyone! (How I wish someone lived decently close so that they could tell me if my car is normal haha, first time driving and 8 and it's not like I can just go to a dealership and test drive another one to see if everything is normal)

micvite

well then, guess I'll wait for it to show up haha.

that depends, my other car that got crashed that I built myself was a 2002 mustang gt supercharged with 450 whp and I could let it slow down in first until idle and it wouldn't even twitch, then keep going at idle. (Maybe it was the higher idle and the huge hp though?) Haha I know that much, I always try to keep it at around 3500-4k while driving and it just loves to take off, I love the fact that the torque comes on fast and just stays constant all the way up, it's like the car just wants to go and go and keep on going. (I must say driving from seattle wa to atlantic city nj was extremely fun, all the twisty roads were simply perfect and the car felt like it was running superglue for tires)

Loki

iTrader: (1)

You'll get the hang of being smooth with these cars. Takes a bit of time. But after that you can be smooth in anything.
A good cat is worth hundreds of dollars, don't scrap it A bad cat you can just knock out the catalyst and have yourself a factory midpipe
But I would caution against a DIY straight pipe. These cars can be VERY loud if the exhaust isn't mitigated somehow. A good midpipe manages that.

micvite

I was assuming that it was bad haha. I don't mind loud, as long as it's good loud if you know what I mean, in fact i love loud haha. I would be taking it to an exhaust shop anyway for the straight pipe (they're really good and cheap too, 100$ to straight pipe my dodge charger 5.7 and the car had no drone like everyone complains about without the resonators and mufflers and it wasn't raspy either)

for coils and plugs, should I got with a cheaper either OEM or aftermarket comparable to OEM for now until I can get like a bhr kit? Like I said I'm fairly broke right now for the next few weeks.

Loki

iTrader: (1)

You can get good coils at NAPA for much cheaper than the dealer.
BHR is good but more expensive, so it depends if you plan the car at least 2 coil changes so 50-60k miles.

Same for spark plugs. They're all the same NGK spark plugs, whether you get them from Mazda or Napa.

micvite

I guess I'll do that then, let's see if autozone has the tools I need to get in there and change everything myself haha. I probably won't be driving more than a few k a year so 50-60k is another 10 years by my current driving (50-100 miles a week as my daily driver)

UnknownJinX

You will learn how to downshift to 1st eventually. I learned it since it's kinda necessary with the potato low-end torque.

If it feels like the transmission isn't cooperating, I'd fill and drain with some good fluid. I am currently using Motul 300 and I like it.

This car is the bad kind of loud without a resonator.

Imagine a Honda Civic fart can but even sharper. It will make your ears bleed. Nothing like the deep V8 rumble.

And you need to get a quality mid-pipe. BHR is highly recommend since not a lot of resonator will survive the exhaust heat a rotary engine can produce.

I get everything from Mazmart because it's still cheaper than all the sources I can find in Canada.

Mazmart asks for US$65 for a set. NAPA/dealer ask for CAN$40+ for one.

micvite

eventually I'm going to have to drain and redo everything just trying to get the engine done first haha, I'm probably going to do trans and diff next, I'll take a look at the bar midpipe then, I'm really only used to driving giant v8 power plants, so I get the torque being abysmal, one of the things that worried me about getting the car but it's so much fun to drive I'm getting used to it haha.

micvite

So... I just got an obd2 scanner and was playing around with the car to check a/f and stuff like that, I noticed if I let the car idle (say 10 mins or more) it will go to redline just fine, no hesitation at all, if I pull to redline say through second gear slow down and try again, it starts to hesitate and buck a bit but itll still make it and it progressively gets worse and worse and eventually a CEL for runners stuck open p2004 and or p2005 until I let the car idle again for a while(I can clear code and it wont show up again until 2-3 pulls later or whenever i stay over 7k for extended periods of time). (I have no idea what this means!!!) Also the car seems to be running a bit rich (10-11:1 at high load and rpm)

STJIMMYJ

I'm hoping you guys can help me out,
I have a 2004 Mazda RX8 that is showing symptoms of a clogged catalytic converter. I've been reading lots of posts where you guys mention; uneven idle, shaking, misfires at high rpm are all symptoms of clogged cat. My question is; is there a way to unclog it or do I have to install a new cat?
I'm also planning on replacing ignition coils in case they were damaged.
Any tips are appreciated, thanks in advance!