2004 RX8 Automatic. Good sounding crank but won't fire up. Advice needed!
 

I was having a power loss issue as well as a low idle problem recently so I replaced my vacuum solenoid as well as inspected all hoses, with no visible damage or cracks. Replacing the solenoid kept the idle steadily between 900-1000 rpm, but would occasionally drop down to 750 and rattle. However the power loss issue was almost nonexistent and the car ran great until 2 days ago I drove it home from work (still running great) and parked it outside my house as I always do. Go out to head to work the next day and to my surprise I turn the key and hear nothing but a good crank from the battery. Tried hooking a jump starter up to it, no change. It doesn't sound like anything under the hood is trying to fire at all. I checked compression to rule that out first and got reads upwards of 120 psi from both rotors, so compression is fine. Car has a clean, updated SSV with new rubber grommet. Recently replaced coils, plugs and wires. New MAF sensor as well as a new battery recently. One thing I know I've been needing is a new catalytic converter because mines awfully disintegrated inside and clogged, but would that finally going out cause the starting issues I'm having? Any advice on what I can try?

Hmm,

How much gas in the tank? Is car at an angle?

You have already done most of what I would have suggested. Does the exhaust smell like fuel? If so, you may have lost spark, could be the Eccentric Shaft Sensor or connector. If it does not, you could have lost the fuel pump, or the car is parked such that it cannot pull fuel (driver side higher, low fuel in tank).

Best I got right now.

Little over a quarter of a tank, just out another gallon in just to be sure. I went ahead and took the tire off and pulled the plugs (NGK) and all 4 are half asked at best. From just trying to start the car today the ends had excessive fuel residue built up so I grabbed my rubber handled pliers and had my uncle crank the key. Got steady spark but it was weak and yellow and I was also able to see some fuel it wasn't burning up completely. So I'm currently waiting on a new plug set due here within the hour. I'll post updates when I have them. Thank you so much for the input!

That's weird, you said the plugs and coils were recently replaced. It sounds like the car flooded, but that shouldn't happen on a fresh ignition. What coils are you using?

I should clarify, I bought the car with a little over 76,000 miles. When I bought it, it had NGK plugs and wires so I knew they were changed at some point, most likely recently but now with this issue I pulled them and sure enough weak spark. Just factory replacement coils I'm pretty sure, I have taken them out and inspected them, they look pristine. New plugs are installed and a few cranks later it started up. Now back to addressing the lingering power issues from my P0661 code that won't go away lol

Query - Are they ACTUALLY OEM coils? There's a few sets out there that look similar, but aren't.

I couldn't tell you for certain, they were in there when I bought the car but I've removed them all and they look identical so I'm assuming they are legit OEM.

Not to harp on it, but did the old plugs actually look worn out? Heavy deposits?

Because when you replaced the spark plugs, you also automatically removes the flood condition, but it could reflood if the root cause is somewhere else. If your coils aren't putting out enough of a discharge, for example.

Thanks,

They were in bad shape, yes. Not the worst I've ever seen but definitely needed to be replaced. Car is running good again. The only issue I'm still having is a minor acceleration delay at times, especially when at full operating temperature as well as the idle periodically dropping down to 700-750 rattling the car slightly then moves back up to 900-1000. Does that every few seconds when idling in gear. Car idles perfectly when in park but when I drop it into reverse or into drive the idle drops to the low 700's again, rattles and jumps back to normal. Any suggestions or experience with issues like this?

Is the AC on? The compressor puts a noticeable load on the engine and idle will fluctuate when it cycles. Try it without the AC and with the vents set to blow at your feet only.

Not sure about acceleration delay. It could still be ignition related, suggest you test all 4 coils using a multimeter.

If it's an 2004 must ask......do you have the original starter in the car?. What kind of CCA battery do you have in the car and how old is the battery ?.

The original starter is a N3H1 and they were slow and weak , about 1.8 KW and slow cranking rpm's. You should have round 720 to 800 CCA and an up graded starter which would be N3H1-A if your buying where you can see the label. Some of the remans which aren't bad but you must take care to insure the new starter is an up graded starter. I have seen a so called up graded starter being sold as reman but what reman an old N3H1 reman which of course is no good because it is a remaned version of what doesn't really work.