Hey everyone, my name's Grant and I recently bought a 2009 RX-8 Touring (automatic). I have been trying to post this in the S2 troubleshooting/help section but it won't allow me (assuming because I'm new). Apologies if this post is misplaced. Over the last month and a half, I have decided to replace the engine in my RX-8, for multiple reasons including low compression, leaking coolant seals, damaged rotors. I ended up buying a brand-new (not remanufactured actually brand new) 6-port 13B. fast-forwarding to today, the new engine is in and it starts. It idles perfectly and sounds amazing. But after the car begins to warm up, the idle begins to get very choppy and rough. I slightly revved up the car and it struggles and backfires. After taking it on a short drive it has very limited power and sounds like it is backfiring like crazy. Then it begins to die on idle. When you press on the gas it backfires and acts like it is going to die. You can drive it but it sounds horrible and you can go more than 20-30mph without it freaking out. But sometimes if you work the gas peddle just right and get the RPM's in the 3-4 thousand range it will sound perfectly fine until you let the RPM's drop or go over 4. The whole ignition system is new (coils, boots, sparkplugs) I took out the spark plugs and two of the four looks a little black on the tip while the other two aren't. But the plugs are new. Now if I go out to start it now that it is cold it starts right up and has no issue until like 5-10 minutes once it gets warm. Could something have been misplaced when swapping the engine? My mechanic and I who put it in have come to the conclusion that it is a sensor. I've heard it could be multiple: Mass airflow sensor, throttle position, e-shaft sensor, whatever the altitude sensor is called. I personally think it is the throttle position sensor going bad. Hoping I can get some help and input here as I'm not sure where to go from here as I've already put way too much money into the car and not looking to put much more into it haha. Thoughts? Thanks.

 

Are the plugs, coils, and wires OEM replacements? Take the catalytic converter off and inspect it. If it's clogged up (which could've killed engine 1) it will kill your new engine.

also, make sure the plugs and wires go to the right ones. 2 lead plugs, 2 trailing plugs, and the wiring obviously to each. If the coils are not OEM, swap them out. Give the MAF a cleaning.

 

Did you verify the engine put in had good compression? Any time an engine in this car is acting up only when warm that can be the issue. Always do a compression test especially on a new engine. If compression isn’t the issue I would guess an intake or fuel issue.

 

Thanks Danny, the coils I said were new because they were the first thing I replaced when the issue began. So I know it isn't the coils/boots as they are new. Unless they were bad out of the box; they aren't OEM. For the cat, it didn't seem to have an issue before the engine swap or at least it wasn't nearly as bad. I have not been able to take it off as the cat/exhaust pipe has a small weld bead holding it onto the exhaust manifold. I'm not sure if this is how it comes factory from Mazda or if some previous owner decided to weld it on.

 

I bought the engine new from Pineapple Racing, they seem to be a very reputable rotary shop. I asked if they did a compression test before shipping and they confirmed. Here is the response I got: "We pressure test the cooling system to ensure no coolant leaks. In this case, it held 36psi for 3 hours. FYI: max momentary pressure spike in a cooling system is about 30psi for milliseconds. We also comp test the engine, but with the assembly lube giving high readings, we are only looking for consistent pressure to each chamber." So I didn't get exact numbers but I'm fairly confident the compression is good. I also had to swap the rear plate from my old engine onto the new one as it needed to be swapped as it was a manual trans. engine. I believe the starter mounts in a different spot? Anyways it looked good when the rear plate was off, new rotor, all seals looked properly aligned/seated.

 

I went ahead and took out the MAF and gave it a good cleaning with Mass Airflow Cleaner. problem persists. I did notice there seems to be some sort of diode looking thing that looks burnt? I'll go ahead and attach a picture. Does it look like an issue?

 

The cat shouldn't be welded to any other part of the exhaust. It is connected by three bolts in a triangle shape to the manifold and 2 bolts with springs at the catback. Why would they weld it?

Definitely check the Maf. That's my bet. Always start with the simplest things.

 

Yeah, it's weird the weld is right next to one of the three bolts connecting it to the exhaust manifold, previous owner also put a new exhaust on, I'm going to try and drop the cat tonight and see what happens.

 

So I bought a new MAF sensor, still no luck, the problem persists. Also, I noticed if you very gently press the gas it will be fine and sound normal other then what it fell like some power loss. If you press the gas a little too fast, like regular driving, it has almost no power and the sound of like a few dozen tiny backfires comes from the exhaust while RPM's don't move much at all. Any ideas??

 

That sounds like some serious issues with the rebuild and they need to fix it. I’d tell them what’s up and tell them to fix it.

 

Is this mechanic experienced with rotaries?
It could be a whole bunch of different things, possible someone goofed in the install. Is the check engine light lit, and are there codes?
If you can't go over 3k it could be in limp mode resulting (usually) from issues with the oil injection system, but again, there would be codes.

Does it restart well when warmed up? Pineapple is quite reputable yes. I'm a little surprised they have new engines, but whatever. I don't think the engine core is the issue here.

Get codes, if there are no codes, get OBD data for airflow, short term and long term fuel trims and rpm while fully warmed up and idling. There may be clues there.

 

alrighty, so it has been a few days. I have since replaced the MAF, nothing/no improvement. I also took out the throttle body and cleaned, inspected it/cleaned connector. We also used an OBD2 reader with live readings and watched the throttle body sensor response to pressing the gas and it is working. So it seems the throttle body seems to be working well. I brought it to a local shop that has a mechanic experienced with rotary engine vehicles. He said it was most likely the fuel injector wires begin put in wrong. As they are very easy to confuse. Does anyone have experience wiring them?

Current Symptoms:

• Poor throttle response/lack of power
• squeaking noise on acceleration sounds like a pully (maybe unrelated)
• rough idle once warm/struggles/sometimes dies on idle
• once warmed up, accelerating at moderate speed causes the car to make lots of tiny backfire noises from exhaust and car has no power/rpms don't move, but if you let off and slowly press the gas pedal it will accelerate/bring rpms up.
• care doesn't want to throw any codes other than a pending P302 (Cylinder 2 Misfire). The check engine light might flash then go away
• buzzing noise coming from the back of the engine bay/under steering wheel. Can't pinpoint it.
• The throttle body was making a buzzing noise when the key was on the on position without starting the vehicle.

The only symptom that occurs when both hot and cold is lack of power and squeaking noise.

What I've replaced/done:

• Ignition system. Plugs, boots, coils.
• cleaned/inspected TPS/throttle body.
• Replaced the MAF sensor.
• Removed catalytic converter, doesn't seem to be clogged.

I think next I will see if the injector wires are installed correctly, the only problem is I don't know how they should properly be installed. Does anyone have a diagram for a 2009 Touring Automatic injector wires or a way I can tell if they are in right? Can't seem to find one as I've heard the wiring is different on some RX-8's. Also, does anyone know if the throttle body should make a buzzing noise when the key is on the on position but not started? Thanks.

 

Have one for the series 1 I was able to find. Don’t know if it’s different on series 2 though is the only thing.

 

the S2 only has 4 fuel injectors vs 6 for the S1. You will need the specific wiring diagram for your model year.

 

See if these help

 

oh, I needed the APV position sensor info for an S2 LIM swap onto an S1. Thank you!

 

Is that a compliment from Team...........

 

sorry, won’t let it happen again

 

S2 2009 Mazda RX-8 Touring - Automatic - 118,500mi (new 6-port 13B engine w/ rear plate swap)
Alright so it has been a while and I thought I would recap what I've done. The car is running a lot better than when I first created the thread but still has major issues and definitely not fixed.

What I did:

• Changed/New Spark Plugs
• New Coils + Boots
• New MAF
• Checked for clogged CAT (not clogged)
• checked for vacuum leaks (no leaks found, done by local shop)
• Injector wiring checked to be correct by the mechanic who helped put in the engine
• Cleaned/Checked throttle body
• Cleared NVRAM

Now, this is the list of things I'm thinking of checking/on the to-do list:

• Stuck SSV valve?
• E-shaft position sensor went bad?
• Bad barometer?
• Clogged/bad injector?
• Air pump going out?
• Bad TPS?

The car is still having problems. It lacks power, rough idle, slow throttle response, stutters, when it gets to the 5-7K RPM range and up it really struggles to get any higher and has lots of small fast "backfires". It is drivable but not a pleasant experience and it doesn't sound healthy. The car has also been a pain in the *** as it hasn't been throwing any codes (other than a misfire code once) until yesterday. A minute or so after start-up it threw multiple codes: P0410: Secondary Air Injection System Malfunction, P0411: Secondary Air Injection System Incorrect Flow, P0139: O2 Sensor CKT Slow Response (Bank 1 Sensor 2).

Some other info: There is a stripped screw on the MAF but it still creates a tight seal so I don't think that is an issue, I'll fix it here soon nonetheless. Sometimes a squeaking noise (almost like a pulley belt) comes from the engine bay when accelerating, might just be a belt or unrelated idk. Also sometimes a buzzing noise comes from the dash/deep engine bay when ignition is set to the ON position. Also, I would like to check if the barometer is working properly but as I have the S2 2009 I can't find any info on where it is located, anyone know? I know it is next to the air pump but not too sure where.

Any help would be appreciated as I would love to get this car back on the road as it hasn't been on the road for almost 3 months.
Thanks.

 

I did not see a confirmation of a compression check being done. Sounds like this is your next move as you are wasting time and money... Get it done!

 

Okay, so It has been almost 4 months, figured I'd give an update. The car finally is in working condition and I've put around 600miles on the new engine, break-in miles are complete and the oil changed. We found out the issue around 2 months ago. It all came down to the tension bolts. When we swapped the rear plate of the engine and reinstalled the tension bolts, we failed to follow the torque specs, as it was overlooked in the process. This left small gaps between the rotor housings. All of this lead to bad compression, as well as coolant and oil leaks. After getting the engine, pulled, torqued, and cleaned, it was reassembled it re-installed. Goes to show that all the details matter and if you overlook something it can cost a lot of time and money! Thanks for all the help and suggestions while we where attempting to diagnose the car.

 

Tension bolts? Wow. Thanks for letting us know.

 

Rebuilds are difficult and this is yet another reason I always advise a swap. I'm glad you figured out the problem and have the car on the road. Thanks for the update!