robot

My car stalls every now then. It starts to feel like I'm losing power when I give it gas and idles really rough. I usually hear a loud noise coming from the engine before it happens. The noise sounds like rattle or loud air leak (of some sort). I haven't gotten a CEL either and it doesn't sound like any of the MIAC videos posted on here. I checked the all the hoses I could find and everything seems to be connected correctly. This only happens once every few weeks but I want to fix it before it gets worse or causing other issues.

I decided to buy a OBDII scanner to see if it was a sensor going bad and to get a better insight of what's going on. I bought a BAFX bluetooth and I'm using it with Torque Pro on Android. A few of the tests failed but I'm not sure what they mean. Can anyone provide insight on what they mean?

I have a 2008 RX-8 Sport with 32,000 miles on it. I changed the spark plugs, coils, and wires at about 30,000. The test results are pasted below.


Vehicle Manufacturer: Mazda
Vehicle Calibration ID: N3M5EK00013H6020
Test report:
------------------
MID:$10 TID:$04
High sensor Voltage for switch time calculation - O2 Bank 4 Sensor 4
Max: 0 Min: 6,177
Test result value: 65,520
FAIL
----
MID:$10 TID:$05
Rich to Lean sensor switch time(calculated) - O2 Bank 4 Sensor 4
Max: 18 Min: 6,162
Test result value: 65,520
FAIL
----
MID:$50 TID:$05
Rich to Lean sensor switch time(calculated) - O2 Heater Monitor Bank 4 - Sensor 4
Max: 0AFR Min: 308.85001AFR
Test result value: 3,276AFR
FAIL
----
-
Max: -74.38335% Min: 25.19731%
Test result value: -79.93798%
FAIL
----
MID:$f0 TID:$04
High sensor Voltage for switch time calculation -
Max: 18 Min: 6,162
Test result value: 65,520
FAIL
----
MID:$f0 TID:$cc
Manufacturer defined MID -
Max: 1 Min: 8,273
Test result value: 52,464
FAIL
----
End of report.

RIWWP

iTrader: (2)

None of those appear to be important. We don't have a bank 4 to even have a 4th sensor in it, and the 65,520 result values look suspiciously like the 16bit max value of 65,536, so I'd think that those just timed out while waiting for a sensor that didn't exist to send it's information.

Stalling at idle can be a number of things though, including vacuum leaks, front O2 sensor failure, clogged cat, low compression, MAF fouled, ESS fouled, missing intake screens, aftermarket intake, and failing ignition.

The noise that you hear when it does is concerning though. A vacuum leak might give you an air noise, but it would be pretty consistent all the time, not occasional. The rattle is worse. Unless it's just the stalling change in vibration that is wiggling a heat shield against something else for that last moment as it dies?