Introduction and help needed with problem
 

Hello RX-8 Club,

I have recently bought an RX-8 (2004, 121k kms, manual) that doesn't run right.
I've already found lots of information on this forum and I'm very happy with that, but I have one problem that I can't really find the answer to.
My RX-8 has a very hard time idling, and when you try to increase the revs with the throttle it starts stumbling and the revs barely increase. And if you press on the Throttle too much it chokes and dies. All of this happens when stationairy, driving it is pretty much impossible. It doesn't give a check engine light and there are no fault codes in the ecu.
After looking around on this forum for tips, i cleaned the MAF and the ESS. And I changed the coils, wires, and plugs. But that has not fixed the problem.
I then discovered that if I unplug the MAF sensor and then start the car it runs a lot better. It idles reasonably okay and when I press the throttle it revs up fine and doesn'st stumble at all.
Does this mean my MAF is bad? or does this mean that something else is wrong?

Welcome to the club. I'm surprised it even works with the MAF disconnected. It shouldn't start at all without it plugged in. If you are getting no codes best way to figure it out is data logging. Could be a small vacuum leak somewhere.

Thanks for the reply,
I was surprised as well haha, especially since it runs a lot better without it than with it.
Can a vacuum leak make the car run so bad that it becomes undriveable? I thought a vacuum leak only really affected the idle.
I'll look into datalogging, I have an obd2 scanner so should be possible.

Absolutely could affect idle which is your issue. Its worth looking at STFT, vacuum, cooling and other good info. The MAF could be damaged but only real way to know for sure is to replace with a known good one. If you know someone with an rx8 would take only 5 mins. Its just 2 screws that hold it in.

Definitely sounds like a vacuum leak. A sizeable one too.. loose hose? There should be 0 air gaps anywhere in the intake after the MAF. Is the intake original?

Yes intake is original, and all hoses are attached to it.
I'll check for vacuum leaks in the rest of the lines, any line that is known to break I should check specificly?
The MAF seems to have been replaced at some point as it is not the original one. Sadly don't know anyone with an RX-8 so can't easily test another MAF without buying a new one.

Replacing the MAF ended up fixing my problem. The old one that was in the car was some sort of cheap knockoff. Replaced it with an OEM one and it runs great now.

Glad you got it sorted out!