What the HECK is going on?!

Get this story....

I was just sitting there idling, when the car started to lose smoothness in its idle, then started missing on one rotor sporatically, then the engone seemed to be running only on one rotor from that point on.

I popped the hood, got out of the car, and saw that the engine was rocking side to side liek id does on one rotor.

I closed the hood, went to get back in the car, and noticed my ever dutiful car alarm had just locked me OUT OF THE CAR!

I go home, (2 houses away -whew) and go to retrive my spare remote.
Battery is dead in it.
Inspected battery, and notice that it was 12 volts.

I grabbed a power transformer with a variable selector for voltage, changed it to 12v, and used the bare wires to give life to the remote.

POP

Okay, apparently reversing the polarity on the remote contacts detonates the chip on the little board.

crap.

I go to the garage to get the standard coathanger, couple rags and some flat blade screwdrivers to pry the door back and hook the lock latch with the hangar.

I get back to the car and after about 5 seconds i notice that the car is smoking WILDLY from underneath the front of the car.

I look under the car and the exhaust is WHITE HOT at the front of the big cat!!!

(I had JUST installed this exhaust from all new stock parts! - to finally pass emissions)

NOW I MELT MY NEW STOCK CAT?! CRAAAAAAAAAP!

I stand there thinking that I am about to burn my car down and try to get into the door as fast as i can without destroying anything on the paint, etc...

The smoking gets WORSE.

The heat sheilds are starting to burn off the stuff on top of them!

At this point i whip off my outer shirt and wrap my vice grips in it and go to the passenger window.

I have to get into the car and turn off the engine, and i have a spare pair of windows for S5 cars.

(I have never EVER had to break out a window)

I sling the vicegrips and shirt at the window and smash it out.
ugh. what a horrible sound and sight.

I reach in and turn off the car.

As programmed, the alarm unlocks the doors. -thanks.

(NO that is the default setting for the alarm, I didnt program this "feature" and I had just put the battery back in the car and the default programming was in place as a result).

<<<<<<ANYWAY>>>>>>

Today i found that:
The engine has great compression (tested with a Mazda digital compression tester ).
the coils are fine.
the wires are fine.

Both rear plugs were VERY SOOTY black and dry.
The front trainling was a bit sooty and dry.
The front leading was a bit sooty and wet.
My cats are FINE! dont ask me how.
There are NO engine codes.
I cant get the car to start after removing the cats ans downpipe (for fire safety)
It smokes and just wont start.

What causes this?
1991 coupe, N/A engine, manual transmission.

 

could be a bad injector/injectors causing you to run extemely lean/hot and the rotor to stop firing.

 

wouldnt that cause a code on a S5?

 

IF it has compression, either it isn't getting fuel, or isn't getting spark. I would start by testing for spark since its much easier to test. If thats not the problem, then for some reason the injector isn't firing. Either bad wiring or bad injector. Or the ECU is acting up.
I'm currently trying to fix this problem on my car, too, so I feel your pain.

 

no clue, but if its supposed to throw a code i wouldnt eliminate it as a possibility just because its not doing so. im not sure what else could make a cat that hot that fast except for being EXTREMELY lean.

 

but these suggestions lead me to think that there is no fuel in some way, however i thoughta glowing cat was indicitive of a huge amount of unburnt fuel being dumped into the cat.

no?

 

The cats you put back on could be clogged that would be another reason. Just and Idea. Good luck.

 

Sounds like you're not getting spark on one rotor...fuel is getting dumped in and out to the exhaust. You may simply have a fouled sparkplug. Take a new plug and lay it beside the strut tower ground. Test each wire with this plug by cranking the car for a couple of rotations, long enough to see blue/white spark. Once you've verified spark on all wires, put the new plugs in the engine and fire it up.

Then if the car still doesnt run right you've removed ignition from the list of possibilities...left with fuel and compression (which has also been eliminated).

 

no kidding.

And the cat was a new-old-stock turbo cat.
Had it in the attic for the day that I got new stock y pipe and mufflers.

(It sounds so quiet that if it wasnt for the fan, I might be able to sneak up on someone if they were say... talking on a cell phone.)

I inspected everything and the exhause seems fine - unmelted.

what is inside that 1st cat? sounds like a brick!

 

I've seen this exact failure before. If it's not what Kevin suggested, then it sounds like a bad injector. They can stick open (or half open) and drown one rotor in fuel. Since the rotary will continue to run even with ridiculously rich mixtures it makes the car act like it has a blown engine and the exhaust turns red...