rough idle when hot
 

hey guys and gals..2004 RX8 60k auto..sometimes not all the time my car has a rough idle...only when driving for a while or putting in park when hot..when i start the car in morning it idles great up until i drive to work and put it in park and then it has a rough idle..also sometime when reving up it backfires a little..also i hear when taking off when warm ill get the rpms up and when going to 2nd to 3rd its makes a sound underneath..please help..

We are going to need more details about your car:

Mods
Driving style
Maintenance history
What you have done to this point to help resolve the issue

This is a good starting point to help sort out the minor to major issues that could be the problem

no mods all stock..just bought about 2 mnths ago..just had new wires plugs..60k service..royal purple diff change..trans fluid change..drive about 40 miles both ways to work..get on it everyonce in a while..cause i know these things like high rpms..93 or above octane gas...no cel ever..

The reason why it idles fine at first is because probably the car hasnt been warmed up enough to get to its normal idling speed. When you first start your car, its about 2000 or higher but when it finally warms up, it is around 900 or so. My car does the backfire but I have an aftermarket exhaust which is known to do that. Do you mean a popping sound? or a loud boom? The popping sound is pretty normal for the car. With 60,000 miles on it, you may need the MAF cleaned (mass air flow) and or new motor mounts. Motormounts are inexpensive but dont know the labor charge. If you are not a DIY kinda guy, you can have the dealership clean the MAF. I believe around $60.00 Hope this helps, other than that, I dont think anything major is going on.

You don't need to take it to the dealer just yet..... Buying a rx8 used can always be problematic

The Rx8 has been known for a normal rough idle, especially in the AT version. Depending on how rough it is do the following.

First I would go to auto zone and get some MAF sensor clearer and do it yourself- Clean the the sensor and check for oil in in your airbox. see how that goes DIY threads can help you through this.

Then

If there still is a problem check your coils, plugs, and plugs wires. Check the DIY threads, all the info you need is there.

If still a problem

Reset your E-shaft sensor. put the key in the ignition, then turn the key but don't start the car, Pump the brake pedal very fast about 20 times until you see the oil gauge do a sweeping motion. Then turn the key off, then take the car for a drive. It will take a few drive cycle for the fuel trims to level out--- car might run rough but the PCM will level out eventually. DIY thread on this as well.. Look at it

Then...


Decarb--- Seafoam Might not be a bad idea to do this anyway with 60K and being the second owner. DIY thread on this too....

This is all thing you can do without going to the dealer.


Some things that might need dealer attention if the above fail to solve the problem

SSV Value issues
Vacuum leakage--- check with meter
Compression test-- 6.5 min



90% of what is listed can be done yourself without the dealer getting involved. please check all the DIY threads and use the search function to help walk you through any concerns. Save you money don't let the dealer do easy work.....

Buying a used car can always lead to problems and issues that the seller may have overlooked or failed to tell you. I hope you took the car to a mechanic that knows rotaries before buying. Also, look at the TSB's that have been issued and make sure they all have been completed.

Sounds like your taking the right steps. Read thought the forum and take in as much info as possible


Don't be afraid of running the car hard

Pico your a genius, Im serious..i did the reset..it did run rough for a while,but i also put some fuel injectory cleaner..lucas..and filled the car drove for about 3 miles cleared right up..no probems since..

^ Not a genius, just simple troubleshooting that's all.
I use Bg44k regularly to treat the fuel system-- great stuff

Glad your car is running well now

Simple troubleshooting... but too many fail to even perform that around here anymore.
People are too quick to advise someone to throw random parts at a problem without proper troubleshooting and that is a frustrating problem.
The mindset of some members here: Spend money -> when that don't work, spend more money -> when that don't work, spend more money -> wait for payday because you blew all your money on unnecessary components -> etc...

Its good to see Pico at least trying to help with more than the usual BS replies!
OK... I'm done venting :)