Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

2004 RX-8 heat up and shut off

own a 2004 RX-8, changed plugs,coils, and cat, car will heat up and shut down for about 30 - 1hr start right up? can gas cause this? after replacing the cat, been running good, but rough yesterday after a fill up?

To see if the trouble is fuel related simply spray a small amount of starter fluid into the intake when the trouble happens. If the engine fires then you know the trouble is with the fuel delivery somehow. If it doesn’t fire up then the trouble is most likely with the ignition system.

Very unlikely it is the gas, do you have any check engine light? you should. If not get the codes read and see what they say, free at many auto parts stores.

After replacing the cat, thought that was causing my problem, will continue to investigate

Google this; 01-008/05 mazda bulletin pdf
Do you have any of the listed symptoms? If you do, it might be worth paying to have the PCM flashed. I’ll assume the dealer would charge more than 0.3hrs, as you’re out of warranty.

Early Mazda RX-8’s had a whole slew of problems that lead to poor starting.

What you described, and correct me if I’m wrong, is this:

When the car is ice cold (first start of the day), it cranks up perfectly fine.
But after you drive the car for a while, if you do a short stop (say to refill the car with gas), you then have a hard time restarting the car.

If this is the correct problem, there are several causes for this.

Poor primary ignition system.
Ignition coils, spark plugs, spark plug wires.
Luckily, you have replaced all of these already.

Clogged catalytic convertor.
You’ve already covered this one, too.

Weak starter.
The early '05 and '5 RX-8’s were shipped from the factory with a weak starter.
As time rolls on ,they are no longer capable of cranking the engine over fast enough to build up enough compression in order to fire up the rotary engine.
A replacement starter spins faster, increasing the compression just enough to make ignition happen.

Weak battery.
A weak battery spins the starter slower, and this leads to similar problems as mentioned above.

Faulty fuel pump.
Again, early '04 and '05 fuel pumps were not the longest lived items on the car.
They tended to cause more issues that wound up being blamed on other components, until someone pulls out a fuel system pressure gauge, and tests the car.

Low compression.
Weak compression leads to not only low power, but hard starting.
All RX-8 engines from '04 through '08 have the tendency to lose compression over their lifespan. Some engines needed to be replaced early in the car’s life due to faulty ignition and catalytic convertor parts that lead to rotor housing damage, or badly carboned apex and side seals that decreased compression to the point that the car becomes unreliable.
Only solution for low compression caused by wear is a full rebuild.
Carbon caused compression loss can be cleaned out with heavy doses of carbon cleaner, to the point that there is a special procedure to perform carbon cleaning on rotary engines.

And no, I didn’t stay at a Holiday Inn last night.
I own a 2011 Mazda RX-8.