Hello fellow RX8 owners and thank you for welcoming me into this club. Let me start by saying this is the first time I have ever joined a car club therefore this is also my first time posting. I apologize in advance if I am posting in the wrong area. Here is a basic rundown on my issue. First of all I believe I am running too rich. There is a distinct smell of un burnt fuel when I'm on idle. Also my gas mileage is terrible. Yes I am aware the RX8 in general is bad on gas. Not really my concern. My problem is, after driving on the highway at constant 100km+ the car experiences a power loss, especially during an incline. The car eventually boggles down and dies. Will not start, but does crank. I then wait about 10-15 minutes then it fires right back up like nothing happened. Again this only happens when I'm on the highway. She gives me no problems at all on the side roads other than the fuel smell I mentioned earlier.
The following are the things I have replaced to try and solve this issue:
-New plugs, wires and coils
-New catalytic converter
-New Fuel pump
-New Radiator
-New Rear o2 sensor (changed when catalytic was changed)

I really am at a loss as to what the issue could be. I do have a feeling it could be my ssv getting stuck open/closed. However I am only saying this after spending numerous hours searching the forums. Please anyone help me with suggestions. I really love this car, it looks and handles amazing. However I have only had it for 8 months and already have cost me alot of cash

2004 Mazda Rx8 M/T

 

My next step would be to find a vacuum leak. If you have an OBD reader, you need to check your airflow and short term and long-term trim numbers, as well as any check engine codes. I would have done that before spending money on parts, some of those would have no bearing on this issue (radiator, rear 02).

Can you do that and report back with the numbers on a warm idle?

I'd also check visually for loose hoses and open holes in the intake tract. Does the car have any modifications?

SSV stuck open/closed usually has an associated OBD code, so again, don't guess, get data.



[Edit]. Wait a minute, it doesn't restart if shut down warm? If you've read up, you would know that's a sign your engine is on its way out. Did you do a compression test prior to purchase? What does the previous owner have to say about this? Who concluded that you needed any of the parts that were replaced?

 

Hey Loki thanks for replying. Ok a few things. First I forgot /neglected to mention that I do in fact have a check engine light. The code is P0456 Evaporative Emission Control Ststem Leak ( very small leak, check fuel cap, piping, etc. ) I did research on the forums and figured it was just the fuel cap. So I have one on order and is on the way. As far as mods go, it has a cold air intake made by Mazdaspeed. Upon inspection, there is one electrical wire that is not plugged into anything, just tucked away. Additionally, there us one small tube that appears to have been plugged. Anyway I've had the car for 8 months with no problems so I didn't think those were the issues. Could a "very small leak" really be the culprit? I should also mention that I do have an obd reader but it's one of those cheap ones that connect to my phone via bluetooth. I use an app call OBD CHECK TORQUE (LITE). Howeve, aside from checking/clearing fault codes, all the other stuff is mumbo jumbo to me. I'm sorry. Can you tell me what exactly I need to look for again? I'm sorry.

Now as far as the parts replaced?
New rad I replaced due to an engine coolant leak. Performed myself.
Forgot to mention installed new starter also done by me.
New coils plugs and wires done by me.
New catalytic converter and o2 sensor done by my mechanic.
New fuel pump also done by me.
All these parts except the Rad I had done trying to solve this problem.I am guilty for guessing the problem, but it was all done after alot of reading online.

 

A faulty fuel cap will generally produce a gross or large leak and can be accompanied by an incorrect purge flow. The small evap leak can be as simple as a purge valve or vent solenoid valve slightly sticking, or a tiny split in an evap hose etc. Nothing to be terribly concerned with. The first step I would take is performing a proper compression test with a rotary compression tester. Once you do that you do that, you will know that you have a good or weak base to start with. You are doing all of the right things thus far, but you need to know what you're working with. Generally hot start issues indicate a decline in compression.

 

The regular Torque app is $5, well worth it.

 

I second that.