FairlaneRX

Hello all. Lurking here on and off for a while, as I have a shop where we work on quite a few rotarys. Finally have an issue that we can't figure out, and I'm hoping someone here knows what's up.

The car is a 2004 RX8. We just installed a complete engine in the car from Mazda. While we've worked on lots of these cars, this was our first complete engine job.
The car started up with no theatrics and ran fine until it went into closed loop. Immediately it threw a P0300, ran rough, and died. When restarted and revved, the engine bogs and runs choppy as soon as closed loop is achieved.
It smells pig-rich and after a 2-3 minute session of forcing the car to continue to run, the cat was lit up orange.

Obviously we have a rich condition, but no other codes are coming up save for the P0300. Front O2 is reading negative at idle and positive on accel, which seems pretty normal for these cars, however the post cat O2 is maxed out rich always. Could just a defective front O2 cause all this? My tech seems to think he might have damaged it as he removed the exhaust maniold with the sensor still in it.

I'm suspicious that we may have mixed up the injector plugs or coil plugs, but they were double and triple checked from a wiring diagram to make sure everything was plugged into the right place.

Edit: long term fuel trim is -21%!

Any help you guys could give me would be great.... thanks!

mazdaspeed7

glowing cats can be an ignition timing issue, from the exhaust burning too late in the cycle, and continuing to burn in the exhaust.

FairlaneRX

So what you are saying is I should make sure all those coils are plugged in the correct order, again.

9krpmrx8

If your cat is glowing do not drive it, you will ruin the ignition components and possibly the engine. If it is glowing it is malfunctioning. Delete it or get it replaced.

FairlaneRX

Yeah, we shut it down as soon as we saw the cat temp go over 1500. Actually figured it out... a combination of incorrectly routed plug wires, and fuel injectors hooked up in reverse (secondary wires to primary injectors and vice versa. It's running good now!

We got the car with the intake and engine harness already removed, so we had to go by wiring diagrams to hook everything up, and yours truly mixed up the trailing/leading plugs and primary/secondary injectors. Sigh.

9krpmrx8

Doh. That will do it. Live and learn Glad you got it sorted.