Car won't stay idling
 

Hey everyone

Make: Mazda
Model: RX-8
Year: 07
Kilometers: 47,000

At 44,000km my engine was replaced. 3,000km later I redlined my car and immediately the car died (though still had electrical power). I took my car to a shop other than mazda, since the nearest mazda dealer is 400+km away. This shop stayed in contact with mazda every step of the way and had determined that the throttle body was the issue of why it would not idle properly.

The issue was; I had to continuously tap the throttle to maintain any kind of rpm. If I held down the throttle the car would die. If I did not touch the throttle the car would die. So, I replaced the throttle body and this helped the problem slightly.

For the first 20 min the car was able to idle on its own. If I rev the car up I can hear a rattling sound coming from the rear end (I have no idea what it could be). Now when I start my car, it will idle for 5 sec or so around 1,000 rpm then dip to around 800 rpm and sound like it is going to die. Eventually it does die 5 seconds later.

There is no engine light on. The ABS light comes on intermittently.

If there is anyone that can help me sort this issue out it would be greatly appreciated. Thanks!

Hearing a rattling from the rear end means it's probably the exhaust, as the exhaust is the only thing connected to the engine idle that can be heard from the rear end.

A) Still have a stock air box and intake? Get a can of MAF cleaner and clean the MAF, it can easily cause idling issues.

B) It's also possible that one (or more) of the grounding points for the engine wasn't secured tightly, and the nut or bolt worked it's way loose over 3,000km, and now you are getting intermittent ground, which is causing ignition issues. Might want to trace the wiring harness and locate the ground points and make sure they are secure.

C) Are you still on your original ignition coils, wires, and plugs? They will not automatically replace those with the engine, so if you can't find any confirmation that they were, then you could just have worn out ignition. It should be replaced about every 30,000 miles (48,000km).

D) Check and clean the e-shaft sensor. It's possible that is dirty or fouled, and will cause all sorts of random problems if it's sending even slightly different information than it should be.