Good evening Mr. Lamar and other rotary people,

    I have a starting problem with my rx8, 2004, hi-power version.
108 000    KM.    My car will not start. I replace apex seals and
all parts which was    bad,    but engine not start too.  I replace
starter 2004, e-shaft position    sensor, igniton coil + cables,
spark plugs, knocking sensor, throttle    body activator,  SSV
actuator,. Engine allways wont start, but  when we    pushing car,
on 10 metres car start, and car drive ok, but engine has a
 unstable idle, 750 -1500.    Please help me.    Jaroslav Dibala

    You need to get an OBD II program for your PC computer and a special
    cable that connects to the OBD II connector under the dash.
    That will tell you what is wrong.
    Obviously none of the stuff you changed so far was the problem.

    http://www.scantool.net/
    http://www.obdsoftware.net/
    http://www.myscantool.com/
    http://www.obddiagnostics.com/
    http://www.obd-2.com/
    http://www.autotap.com/
    http://www.obd2crazy.com/

    Paul Lamar

   Thank you very much, but I was on PC in Mazda service. PC tell me
that   range of ex.shaft position sensor is bad, and second rotor
has not good   combustion.   Jaroslav Dibala

   Well if the shaft sensor is bad the engine will not run.

   The latest thinking on early 2004 2005 RX8 problems is the newly
   designed coils
   were misfiring allowing the unburnt fuel to wash the apex seal oil
   out of the engine. Check the coils that you have now.
   If the part number marked on the side of the coils is not
   followed by a "B" replace the coils.

   If the rear rotor compression is still low the engine
   will need to be over hauled. With less than 100,000
   miles (not kilometers) it will be done by Mazda
   for free.

   Paul Lamar

   Hi Jaroslav,   I am not a rotary mechanic, but, it sounds to me
that you   should check, a - check the voltage to the ignition
system, while   attempting to start the engine, b,- check the
voltage at the starter,   while attempting to start the engine. It
sounds to me that there is not   much wrong with the engine if it
will start and run whilst push-starting   the car. It is probably
electrical because it will not start on the   starter.        John Burey.

   John, the wrong name was attributed to the original message so I changed
   your response to correct that. Jaroslav Dibala  is the correct name.

   Good call. I don't know why I did not think of the obvious.
   I guess personal cars are rather new in the Slovak Republic
   or perhaps Jaroslav is a new and inexperienced mechanic.
   Those of us here in North America and Western Europe grew
   up with cars since Henry Ford. We take certain car knowledge for
   granted.

   Paul Lamar

   I´m not a new mechanic :).
  I make some rx 8 engine with p-port too. Voltage is o.k.,  Next problem
  is idle, is unstable between 750-1500 rpm.

Jaroslav Dibala

  Are you using the stock computer with a p-port?
  That is unlikely to work.

  Paul Lamar

  no, no... i have a p-port engine in another car with racing ECU, it
  works perfectly.

I'll try to replace oxygen sensor.
Thank you very much.

Jaroslav Dibala


Jaroslav,

If you have an OBD2 reader, find the O2 area and watch the output volts. It
should bounce around. The sensors output 0 to 1 volt with a target of 0.5V. If
it is working well it will be above and below the 0.5V fairly quickly. Some
readers have a "cross counts" screen. You want a high number of cross counts.
This is the number of times per second the O2 passes 0.5V. An old sensor will
not respond well and not have a bouncing around output.
To verify if the sensor circuit back to the computer (ECU) is good, disconnect
the wiring harness at the sensor. Put a pin or piece of wire in the sensor
wire. Not the ground for the sensor or the heater wires. Then you hold the pin
or wire and touch the positive and then negative battery terminals with your
other hand. This will drive the sensor circuit high and low but not damage the
ECU. With the reader connected you can watch the O2 volts. With 108.000 Km the
O2 sensor is probably getting poor.

Do you have access to a lab scope? If you do you can connect it to the e-shaft
position sensor circuit. Three wires; +12V,ground and signal. signal is the
wire to probe. A pin works well to slide in between the wire and seal. when
running the scope should show a good straight line and then jump high or low
and then return to start position. No curve at change of state and no breaks
in the straight line other than the change of state. Breaks in the line
indicate failing sensor.

Dale Davies


It seems that during cold enrichment, the o2 sensor is ignored by the computer. If the cold idle is incorrect, that might indicate another issue.

I gather the compression is good for both rotors..  On all three seals.


Matt-