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



 As i said before I am not a Rotary mechanic but usually the Oxy
sensor is not read at idle, usually because the engine needs to be run
much richer at idle, so the sensor is open loop until a certain speed is
reached then the o2 sensor goes closed loop, sometimes the switching is
done by the Throttle position Switch, maybe it is closed loop when it
should be open loop. But that should not affect starting when it starts
with a push, a lot of times the ignition switch will go open circuit in
the ignition circuit when turned to start, very frustrating:-[ . But at
100,000km the switch should have not worn out. You could have a vacuum
leak in the inlet manifold ,rubber hose?
   John Burey