Diego Gonzalez

So I need some help trying to figure out what's wrong with my brother's car,
we both have a 2004 RX8 his is the base, mine is the gt
His car had been sitting in a shop for about 6 months because the mechanic he took it too couldn't figure out why it wouldn't pass emissions.
We got the car back a couple weeks ago it finally passed emissions but now when the car is on and in neutral it's idles weird and kind of shakes, and it's much louder than mine (neither have any mods), When we put the car in any gear, whether it be first or reverse, the rpms will start going from a line under 1,000 to a little over 2,000 when it's warm, when it's cold and we put it in gear it goes up to about 3,500 without us even pressing on the gas or anything. Does anyone know what might be causing this problem??
I know the mechanic had messed with the fuel injectors, and he changed spark plugs, cables, and oil before returning it to us.

nycgps

iTrader: (1)

It's kinda hard to tell. u should make sure he reinstall the fuel injector wiring and spark plugs wiring right , or worst case, hope he didn't broke any wires ...

shooting up in rpm range is kinda normal for cold weather, but if it stays there for too long, u might have a problem somewhere else.

the rpm jumps around when the car is in gear ??? what exactly do u mean ? u have a camera phone right? make a video, upload it to youtube then post it here.

Bladecutter

Are both cars manuals or automatics?

Here's what I would recommend that you guys do:

Park both cars next to each other, hoods up, and get a bunch of tools.

Now, take these parts and swap them from the good car onto the bad car, and retest the bad car after every swap to see if the car starts running normally:

MAF Sensor
Ignition Coils (all at once)
Neutral Position sensor from transmission
Clutch position sensor from clutch pedal

I would double check the spark plugs to make sure the correct type plugs are in the correct locations.

Also, does the car have a CEL on?

BC.

Diego Gonzalez

Ok I'll try to get a video up in the next couple days, hopefully that will help me explain myself better,

Both cars are manual, That idea could work if I can get it done in one weekend, my car is a daily driver so i can't afford to have it still be taken apart when monday comes around. and as far as the neutral position sensor and clutch sensor i'm not sure i know where those are located.
As it is no CEL however we did notice that driving it if we push it past 4,500 rpms it will come on, and the code it gives us says something about cylinder 1 misfire.

RX8Soldier

iTrader: (24)

before that, you could read the rules of the forum

Bladecutter

There's your clue.

Start with the ignition coil swap.
Will take you all of an hour to do.

Plenty of threads in the DIY forum to show you how to do it.

BC.

Diego Gonzalez

Ok I'll try switching out the coils this weekend, hopefully that works

Here's the video showing what it does

http://youtu.be/w9yaJaJs-hY

Bladecutter

Your check engine light is on.
Go to an autoparts store (O'Reilly's, Advance, Pep Boys, etc), borrow their code reader, and get the codes that are stored in the computer.

If you are here in Colorado, you won't have any trouble doing this.
I went with one of our other CO residents here with his car to an O'Reilly's in Boulder one weekend, read his codes, and went about fixing his car with the information we learned.

Honestly, until you find out what all codes your car is throwing at you, there's no point guessing.

I still would swap the ignition coils first, since you have access to another RX-8.
If your car runs great, and the other car runs bad, you might have figured it out.

BC.

Chino_rx3

iTrader: (1)

Yep check codes then you can find out what you need to do. Check spark plugs , check coils or swap .. crazy part is I've owns maybe 30 hondas and some of them have done that exact thing and it was idle control valve . But check codes ! Then ill start from their never guess on rotaries that's a waste of time .