doritoboi

Hello.

I've recently run into an issue that I initially suspected to be an electrical problem, but am now worried may be a dead engine. Prepare for some loooong background.

On mile 150 of a 300 mile road trip (perfect timing) my RX-8 very suddenly failed. I attempted to accelerate from 80 mph in 6th gear to overtake a slow semi-truck at roughly half throttle when all of a sudden the engine started very violently shaking and would not accelerate at all. I lifted off and tried to accelerate again, but was met with the exact same violent shaking and lack of acceleration. While still coasting at about 70, I put the car in neutral and the engine instantly died. I then tried to restart the car in neutral using the starter while still coasting and as expected the engine wouldn't start up. As I was still coasting at about 70, I attempted to start it by putting it in 6th and slowly letting out the clutch. This succeeded in getting the engine to start, but any attempts to accelerate were met with the same shaking and complete lack of acceleration. While pulled over on the side of the highway, I tried to start the car about 3 times, but to no avail.

The reason I initially thought this was an electrical problem (and could potentially still be?) was that while waiting for a tow, and running only my hazard lights my battery dropped so low that the car very quickly lost power (in the span of 5 minutes). My battery was at this stage 4 years old (waited waaaaay too long to replace, I know) so I assumed it had failed in such a way that the car just didn't have enough voltage to run the motor. Replacing the battery, however, did not fix my problems and the car still did not start.

In an effort to diagnose the problem, I have verified the following:

• Replaced failed battery
• The fuel pump is pumping fuel (filled half a water bottle in 2 seconds of cranking)
• Verified that the spark plugs do spark (visually confirmed spark)
• Peeked through spark plug holes to see if apex seals were visibly fucked (they looked fine)
• Cleaned all electrical grounds
• Confirmed alternator is good (tested at AutoZone)
• Attempted to de-flood (Cranking with throttle fully depressed for 10 seconds with 60 second breaks in between)

Unfortunately I can't seem to find the problem and the car still doesn't want to start. I attempted to jump start the car off another running car (slightly faster cranking speed due to higher voltage from running car's alternator), but this did not work. I also attempted to start the car using starting fluid sprayed into the intake behind the air filter, and this also didn't work.

The car only finally started when I combined these and started the car off a jump from the other running car as well as putting a bunch of starting fluid in the intake. Once started, the engine ran like crap and I had to help keep it alive with the throttle. I suspect it was heavily flooded as for the first 5 minutes of doing this there was a lot of smoke coming out of the tail pipe (smelled like gas). Once the smoke stopped, the car did idle, but it still idled really poorly, basically constantly misfiring and on the brink of stalling at 500 RPM. There was also a clanking noise at around 1300 RPM when I tried to help get it to idle (not present at higher revs or at idle).

I let the car idle like this for about 5 more minutes after the smoke stopped with it misfiring basically the whole time and not getting better. When I stopped the engine, it again wouldn't start on its own without the starter fluid and the added voltage from the jump. I also noticed that in this combined 10 minutes of running, my cat seemed to be glowing orange (usually the sign of a clogged cat?).

Prior to this fiasco, I haven't had any symptoms of the engine getting ready fail or low compression. Power was good, fuel economy was good (for an RX8), and temps never went above 215F. The engine was rebuilt by Lucky 7 in SoCal about 30k miles ago so the engine wasn't ridiculously old either. Oil/filter changes were kept up with every 3000 miles using Castrol GTX 10W-40 non synthetic, I've been running BHR ignition coil set since the motor rebuild, have been changing plugs and wires every 25k miles, replaced the fuel pump ~10k miles ago, and am running stock everything (besides the coils).

I don't have access to a rotary compression tester and the car unfortunately doesn't run well enough to drive to a dealership to get the test done. The questions I have are as follows:

• Is there anything besides a blown engine that can cause these issues that I may be overlooking (ie. weak spark, not enough fuel pressure, failed cat, etc.)
• Do engine failures ever happen this suddenly? (I was under the impression that most failure modes were more gradual processes?)
• What other diagnostic steps should I take (barring a compression test, as shipping for a rotary compression tester is really slow right now and I am leaving socal on the 6th)
• Could the battery failure have fried some other electrical components that can cause the car to run so poorly?
• If the engine is likely dead, does anything from this story scream poor rotary care so I can learn from this and not have a repeat?

Any help/advice would be very much appreciated.

BigCajun

iTrader: (1)

If you never got a CEL or P0420 code it's likely not your cat but try taking it off or disconnecting it to see if the problem persists to eliminate that possibility.
Try to see if there are any chunks of broken strata blocking the cat back also.

Be prepared to apologize to your neighbors or the police.

Loki

iTrader: (1)

Are there any codes?

What about the eccentric shaft position sensor? Is wiring to it ok? What if you reset the profile?

The battery draining is weird, it's possible you have a short somewhere. Any blown fuses?

I'm not ready to call it a dead engine until we know there isn't an electrical problem or a comp test. While not unheard of, they don't tend to up and die. Aee there metal flakes on the spark olugs or in the oil?

At first blush it sounds like a Spark plug wire popped off

doritoboi

I went ahead and cleaned the ESS and the MAF and was in the process of taking off the cat to inspect it when I realized I needed to get a deep 14mm socket. I went to Autozone and while I was there rented a compression testing kit (I know its not accurate at all with rotaries but I figured I'd give it a shot to see what I can make of it). Long story short rotor 2 gave a reading but rotor 1 did not even move the needle. I think it might be fair to conclude that something in the front rotor catastrophically failed on the freeway and this engine is dead. Bummer.

Regardless I want to investigate what could have caused such a sudden failure and would love some info on what I should look into.

Loki

iTrader: (1)

If your apex seals are accounted for, as you said, then one of the side seals must have come loose and gone for a ride around the housing knocking out the other side seals and shredding the housing. As to why it came out, you might need to open the engine to find out. It happens, rarely based on reports on this forum, but it could be anything from poor installation during a rebuild to a chunk of carbon coming loose from the corner of the exhaust port.

Its weird though, you would expect metal flakes on the spark plug and the apex seals you see through the hole would be manged up from the debris bouncing around in there.