Sentient_Magnum

Hello everyone! I recently purchased a new to me 2004 RX-8 Manual. I bought the car as a project as I am a fan of all different kinds of sports cars and have worked on many different piston engines in the past (Mustangs, BMWs, Civics, etc.). This will be my first adventure with a rotary and I'm excited for the new challenge. I have several issues with this car and many questions I am hoping to get answered so bear with me here. I'll start with a little bit of background.

I have been reading through all of the recommended posts in the newbie forum as I am basically starting from scratch with this car. All I have is a working (supposedly) engine and transmission. The rest is up in the air. That includes the body. I am not really looking into performance modding but I want to get the most out of this car once it is complete (sticking with a NA engine don't want the hassle or price tag of FI). I have been tearing the car apart for the past couple of weeks to see what I really have to do and the list is long.

The car was running before I started tearing into it but it was clearly not running at peak capacity and had some stalling issues after sustained driving. What I did before I started breaking down the car was replace the coils, plugs, and wires to see if that would alleviate some of the problems that I was having. That seems to be the first thing people recommend before really looking at anything else. That did help some but did not fix the stalling problems. Essentially, what happens is after 10 minutes or more of driving the car will stall at idle and doesn't want to crank back up. There were A LOT of different P-codes being thrown and I was able to narrow the problem down to the air pump, oil metering pump, and intake valve solenoids (SSV and the other two whose names escape me at the moment). All of these parts I went ahead and ordered replacements for to ensure that I've addressed the problem.

The first question I have I guess is this, do you think the stalling issue is likely caused by one (or all) of these parts or do you think it is something else? To be clear the air pump was definitely faulty as it kept blowing the fuse. The solenoids and oil metering pump I am not sure about but I thought better safe than sorry.

Second, I want to make sure that I get some life out of this engine so I want to make sure that I flash the ECU to increase the output of the OMP as is recommended here. However, the recommended flash tool (COBB Accessport) is no longer available for purchase and I can't find the second recommended tool (Mazdaedit). I found an option that is recommended by some but I wanted to get someone's opinion who has more experience with this than me. The tuner I found is VersaTuner. Is that a viable/recommended option to flash the RX-8 ECU?

Next, the exhaust. What is your recommended midpipe replacement? The CAT has been gutted on my 8 and I want to get rid of the noise and create a better exhaust sound. Not really concerned as much with the performance as I am the sound. Although performance gains would be a plus.

Thank you to anyone and everyone who answers. I may be posting on here a bunch over the coming weeks. I have a seemingly unending list of things that need to be done to get this car road ready again so any other tips, tricks, opinions on anything related to RX-8s would be welcome. Just for your amusement I'll list everything I have to do to get this thing right.

1. Refinish the inside of the engine bay because of rust underneath where the battery sits
2. Replace the radiator fan
3. Replace OMP
4. Replace three intake valve solenoids
5. Replace air pump
6. Replace the hood
7. Replace the fenders
8. Replace the front bumper cover
9. Replace the air intake
10. Replace the factory radio
11. Replace the shifter skirt
12. Replace the headlights/taillights
13. Flash the security system (Passive system is going off even after cranking)
14. Check the Transmission and Clutch
15. Charge the A/C

Loki

iTrader: (1)

Have you had a compression test? Stalling and not starting is a common symptom of compression loss. I'd start by eliminating that, before buying parts

CaymanRotary

I can’t wait for TeamRX8 to read this one... yes, get a compression test immediately.

Sentient_Magnum

I did get a compression test and everything came back normal. A little on the low end but not ready for a replacement or rebuild yet according to compression.

CaymanRotary

Do you know the numbers or have a readout sheet? Because either you are losing compression or fuel pressure. The fact that it stalls out only after its warmed up leads me to one of those two issues. Low compression seems to be the more likely culprit.

Sentient_Magnum

Well, it appears I was given wrong information about my compression numbers. My numbers were normalized at an average of 6.6 on both rotors and I was told this was ok. Not great but it should still have a decent amount of life left. After reading a little more here I see that 6.6 is on the verge of full failure. Sounds like new engine time. Oh well. I figured at least either the engine or the transmission would end up being bad so I was prepared for this. Any good threads on DIY engine swap? I'm doing all the work myself so any help is appreciated.

CaymanRotary

6.6 should still run. Its below Mazda minimum but in my experience, anything over 6 bar should run and work fine with a healthy ignition system. A readout sheet would be helpful rather than an average. Could have large differences in the rotor faces which could also cause stalling. Your numbers should look like this for each rotor:

X.X Face 1
X.X Face 2
X.X Face 3
XXX RPM.

Sentient_Magnum

Didn't get a readout sheet just got the two rotor averages normalized at 250 RPM. Both averaged 6.6 bar.

Edit: Sorry I should clarify. The faces did not have any significant differences. All 6 were in the range of 6.4 - 6.8.

CaymanRotary

Sounds like they used a regular compression tester meaning those results aren't very useful. You need a rotary specific tester otherwise the test is inherently inaccurate.

Before making the decision to do a rebuild, make sure your engine is actually the problem first. You could just also rebuild it anyways but be fore-warned, it is not easy or cheap. Also as a bonus, you wont know how expensive it will be until the engine is taken apart fully. Could just need a rebuild kit, could need new housings and rotors. This is why I always recommend locating a known good replacement engine rather than do the rebuild yourself. This way, all it ends up being is a simple engine swap that can be completed in a matter of a couple days.

Sentient_Magnum

I appreciate the help. Yeah it sounds like I got faulty information all around. I'll probably just end up doing a swap rather than a rebuild. I don't know enough about these engines to trust myself to do a rebuild yet. I'll drop the new engine in and use the old one to play around with and learn more about it that way. Any recommendations on places to look for an engine? I'll need the 6-port because I have the 6-speed manual transmission.

CaymanRotary

There are rebuilders that sell complete engines though these require a core charge. Meaning, you will need to pay that fee (usually $1,000) if you want to keep your old engine. It will be up to you to do your research and find an individual or company that will help you with your swap. My contacts are all in the Caribbean (Peurto Rico for me) so I doubt it will help you much. It would be more cost effective for you to find someone in your own country that is reputable and provides a warranty of at least 6 months.

CaymanRotary

If that's the case, the engine is not yet the cause of your stalling issue. My 6 speed has almost identical compression numbers and it works just fine. What is your exhaust setup like? That can also be an issue as the catalytic converter is known to clog up.

Sentient_Magnum

The only other thing I have found that explains all the problems I am having is a combination of SSV valve and Air Pump failure simultaneously. I have bought both of those parts. So I'll put everything back together and see if that fixes the issue. If not I'll know the engine is likely the culprit behind the stalling.

CaymanRotary

The air pump is definitely not the issue. All its does is pump air into the cat while the engine is cold. The SSV would also not cause stalling issues as far as I can figure. A problematic one would cause hesitation but not outright stall the engine. I would look at fuel trims, AFR when the issue occurs through an OBD2 scan tool. That would give you more information anyways as I still believe its likely a fueling issue based on your symptoms and the fact that you recently replaced the ignition system. Either that or an issue with the injectors.

GregSki

Hi - Good to know there's someone else out there like me. I just bought an '04 4-port AT with a similar issue. The only codes I was getting were the smog-pump codes. I can do anything with a 4-stroker piston motor, or even a 2-stroke, but never a rotary. I'm currently in the middle of tearing down the motor. I had average 6.4 BAR compression. After driving for about 10 minutes (warm-up), it would bog down and almost stall at every stop (stop sign, light, etc.).

Since the compression test was fairly low, and because I love tearing $#!T apart, I opted for the rebuild. I'm curious to know if any of your issues returned after an engine swap, and I will let you know if the rebuild solved mine or if it ends up being something else.

Right now I'm in a holding pattern until my 54mm socket (a.k.a 2-1/8" socket) is delivered. You will need one of those if you're doing a teardown - that's the size of the flywheel nut. Big sucker. And it's put on with 300 foot-pounds of torque, so no other tool is advisable to try.

Will let you know how it turns out.