User24

iTrader: (1)

Hello. Looking for advice to make sure I cover all bases regarding tests, prior to boarding a plane or scheduling a long distance transport. Right now the car is 1500 miles away, after being towed to the nearest dealership from where it lost power and wouldn't restart.

On a tight schedule and no dealerships open on Sunday, I was forced to book a one-way rental vehicle to unload the rx8 and drive the rest of the way across country. So far at 47000 miles, I've been stranded due to sudden normal engine failure, water ingestion, ignition coil failure, but nothing like this.

Mods in preparation for the drive was the Racing Beat ram duct, oil cooler screens, radiator screen. Ran this configuration with the Injen intake for a few days on the streets without issues.

1. Rear suspension took its last speed bump and collapsed. It gave the rear tires a cartoonish negative camber and the underbody began scraping on banking turns. During travel I was able to correct some of it with an alignement, but the rear end was still low compared to the front.

2. Vehicle was down on power on the interstate and eventually refused to reach higher rpms. I felt the intake noise was excessively loud for the slow acceleration and stuck at a single frequency, ended up cruising at 5000+ rpm, with 10-11 mpg just to climb hills. Got a blinking CEL after several hundred miles, then solid CEL. Did not pack my ODB reader, but performed MAF cleaning, battery reset, ecu reset.

3. At some point the rx8 went into a limp mode: Limited to roughtly 4000 rpm depending on gear, very light throttle only (or it would cutout), maximum speed in 6th gear 81-84 mph. Once I figured out how to drive in limp mode, I got the expected 15 mpg. Did not have any further CEL.

4. Engine suddenly lost rpms, some rough groaning/vibration as it shut down attempting to climb a bridge overpass. Unable to restart and called for a tow.

So far, I have been recommended a PCM reprogram and tightening of a rear suspension screw. The vehicle was reportedly able to be restarted and spark plugs looked ok, but so far I don't have proof of that.

Obviously I will need to know more. Did I somehow loose PCM programming? Why did the limp mode engage in the first place? Why did the vehicle die? Etc.

Unless there are better ideas, I figure I'll need to ask for a compression test, diagnostic/verification of SSV, throttle sensor, OMP, new spark plugs and rear suspension shocks.

NotAPreppie

It might be a clogged cat instead of limp mode.

The only way for the PCM to lose it's programming would be if it were bad.

It would have been helpful if you had stopped at an auto parts store and had them read the code.

Loki

iTrader: (1)

It's a multi-link suspension, camber gain with compression is NOT as large as what you'd see on your average family sedan. So if has cartoonish negative camber, I think something more serious, like a ball joint, has come apart. Also the suspension can't collapse unless you've broken a spring, which is pretty unlikely. Certainly wouldn't drive it until you've confirmed the cause of the "collapse".

Sounds like you lost an ignition coil or 3, and/or the catalytic converter is clogged and it can't push exhaust out. That CEL is flashing for a reason, it's asking you to stop.
Definitely don't drive like this.

What you call limp mode is consistent with ignition coil/catalytic converter failure. Actual limp mode is limited to 3000rpm and most often caused by failure of the oil meter pump motor/sensor/wiring. Don't worry about the PCM reprogram, whoever recommended that doesn't know what they're talking about.

They should have recommended new ignition coils, an examination of the catalytic converter, and an engine compression test. Leave the SSV, throttle sensor and OMP well enough alone, you don't have symptoms for those to be the cause.

Driving it in the condition you did could have EASILY killed the motor, so.. yeah.. compression test.

Suspension screw: sure sounds like it.

User24

iTrader: (1)

I appreciate all the advice and am following through with an eye toward ignition coil problems. This could be the 2nd ignition coil failure of D585 experienced, with only 2,615 miles between.

The compression test was satisfactory, but without any meaningful troubleshooting progress after 19 days at that particular dealership, I have scheduled an auto transport to bring the car home. Apparently it starts, but at this point it is only $100 difference between a winch transport and regular transport. No DTC stored, and invoice noted some "frame damage". Verbally from service writer, catalytic converter looked fine.

Previous ignition coil failure (D585, BHR system): November 2014 @ 45,210 miles. Replaced ignition coils with "genuine" OEM via 3rd party on Amazon, and new spark plugs.

Rotor 1: 850, 840, 890.
Rotor 2: 800, 800, 800.

Possible ignition coil failure (D585, BHR system): March 2018 @ 47,825 miles. Ordered ignition coils from GMpartsdirect, ACDelco 10457730.

Rotor 1: 830, 900, 850
Rotor 2: 850, 860, 870.

If I get stranded on the street again, I would be tempted to change back to OEM ignition coils or just start packing spares.

Loki

iTrader: (1)

If you believe the BHR kit failed, get in touch with Charles/BHR. Their customer service is great.

So your compression is higher in 2018 than in 2014? Is that corrected for altitude and rpm?

User24

iTrader: (1)

Vehicle was dropped off in running condition, and then I installed new spark plugs, coils, and wires. A strange issue remains at higher speeds.

While the car will redline in 1st and 2nd gear without noticeable issues, at freeway speeds there are several hangups in the 3950-4600 rpm range from 4th through 6th gears. During these hangups, the vehicle shakes as power cuts in and out rapidly and the exhaust backfires.

Loki

iTrader: (1)

Possible something is disturbing airflow around your MAF sensor at speed. Is it all stock? Are the mesh screens in front of the MAF in place and undamaged?

User24

iTrader: (1)

Injen intake with Racing Beat ram air duct. Screen intact, trying to look for a partially clogged cat but the front 3 splined bolt nuts are stuck, meaning the previous dealership may not have actually seen it as claimed. 650 ft lb impact isn't removing them so far. Other than putting my own eyes on the cat and a new MAF, I will have to try my luck again with another dealership diagnostic.

Loki

iTrader: (1)

Does the Injen intake have airflow straightening screens? You really need those for the MAF to read properly and avoid drivability issues.. Also most intakes for this car, including Injen, are worse than stock. Roll back to stock if you can.