Struggling to start?? And vibrates at idol?
 

My 04 rx8 seems to struggle when I go to start it? I rev it to 4g when I shut it off so the extra fuel is burned. It just seems like it barely starts. The car also vibrates every 5 seconds or so when it's just running in neutral? Is this normal? An issue? PLZ ADVISE
Thanks!

#1 - the vibration should not be a normal attribute of any vehicle.

The main issue with rotaries - at least the fuel injected versions - is they are prone to flooding when started for a short time (turned off cold). Or when they age, the fuel injectors leak - meaning the fuel system is left pressurized when the car is turned off, and that pressure leaks past the injectors and leaves extra fuel next time you start (not a good thing).
I also think your rev before turning it off could be making things worse. While it should blow the fuel through the system, or just suck in air when it's idling down - something tells me this could result in excess fuel instead of just turning the engine off as most people do.

The vibration every 5 sec sounds like it's trying to compensate for fuel mix... i'd bet the O2 sensor may be having issues. You may want to get a code scanner and see what signals fluctuate at the same rate as the idle vibration.

I know for some models there's a tuneup procedure, for making sure that voltages and sensors are adjusted properly. This procedure is most likely in the shop repair manual - if you do your own work i'd recommend getting the manual and see if you can fix this.

Good luck

Thanks! Your info seems helpful. Quit revving it and check the o2 sensor.
Thanks again

Revving
 

When I heard about the technique for revving the motor before shut-off, I believe the process was to rev aggressively to 7k and turn it off in mid-rev. I hate doing it, so I rarely do.

I have the same issue that you do when running in neutral, and I find that it's aggravated on hot days, especially if I've been sitting in traffic, or when I've been driving the car hard. Heat seems to aggravate the condition, and if I just drive with the car under 4k rpms, I don't have any idling issues. I was dealing with the problem every day this summer, until I started keeping the revs down. It was 101 degrees yesterday, I kept the revs down, and had no problems at all.

I've cleaned the mass air flow sensor, I've SeaFoamed the motor, and run SeaFoam through the fuel system. These all helped briefly with the idling problem, but running at lower heat has been the best thing I've done so far.

So you have the idle vibration but only when the engine is hotter than normal... basically speaking?

I'm wondering if some electronics are overheating on the engine. I recall the early RX8 had a heat shield recall or some such thing - not sure if this was to protect electronics or just to keep from baking off paint.

I don't think it sounds quite right, but if its too hot there could be a pre-ignigion problem you may be able to use a cooler spark plug...

Have you monitored the engine block temp / coolant temp to see if there's a temp point where this starts to occur?

@ squish that makes sense I've ran into a bunch of different opinions on the reving technique. It defiantly seems to act up more at higher temps.
@ Dave honestly I'm not much of a motor head, I've always owned imports but never one that the matinee was do different. I have not checked the temp of the block etc. I'm defiantly looking more into this issue.
Thanks guys

Exactly, when the car is very hot, it will not maintain a steady idle. It will jump to 1300 rpm, drop suddenly to 600, pop back above 1000, and may just suddenly quit. If I've been driving 75 mph on a hot day, I can expect that the car will stall immediately after putting it in neutral when I slow down at the highway exit. I will then have to fight the car the rest of the way home, and it's a guarantee that the car will stall when I pull into the driveway. In the same hot weather conditions, but driving 60-62 mph, the car will have a rock-steady idle when I put it in neutral at the exit. As long as I keep the revs down from there, I don't have an ounce of trouble bringing the car the rest of the way home.

There was a heat shield recall, but I believe it was associated with the exhaust getting the fuel tank too warm at high revs, when the car is producing so much heat.

Wait, that may be it. If too much heat is getting to the tank, could I be vaporizing fuel and creating a mild vapor-lock situation?

DJS, I haven't monitored the block temperature, but I'd like to get that on the agenda.

Hey, just noticed you're in Macedon. I grew up in Rochester...

the warm fuel idea could work, but not if you've been driving for it to occur. I'd think at 75 there would be enough airflow to keep fuel lines from getting warm and that would only occur if idling a while after flogging it.

Let me know if you're still in the area, i'd be happy to help.

I used to have an 04 RX8 also same problems your having let me tell you it aint fun being in a car that everyone admires for looks and performance especially when out in the city where everyone sees you let me tell you what i did to make it last longer it ended up working fine in the end. First when you start it up while on let it sit for at least 2minuates till it idels all the way down because when you turn it on its on high idel,Second before turning it off let it sit for like 2 minuates again to calm down, that will help you on the turning off problem,as for sensors there was always a sensor I had to be getting replaced it was called a Position Senor after that the car ran smoothly keep putting the 93+ gas and you will be fine if anything that that doesnt work change the Sparkplugs on it thets the last thing i did to mine i got rid of mine because i kept getting pulled over in mine by highway patrol dont know if the person before me that had it was a bad person but i would always get stopped well keep it up ZOOM-ZOOM