Weird RPM issue while driving
 

Gonna try and keep this short and simple so I don't confuse/bore anyone:

When driving at RPMs BELOW 5k, the RPMs "rise", though without producing any extra power, when the throttle is pushed down excessively. This does not happen randomly. If I apply regular (aka light) throttle pressure when under 5k RPMs, then I floor it after I hit 5k RPMs, everything is fine.

However, if I were to, say, floor it when my RPMs are at 3k, then the RPMs would definitely jump up to about 5k or even 6k, and then slowly drop back down to where the would be normally (4k-5k).

One good way to compare this problem to something we're familiar with is slipping the clutch. Imagine shifting from 3rd gear to 4th gear, but you kept your foot on the clutch for too long and had this unnecessary "wwaaaaahhhh" of falling RPMs, down to where they would normally be with a proper shift.

I hope I adequately described the problem, but it's not easy to. I may end up taking a video if you guys have absolutely no idea what I'm talking about, but I'm sure this has happened to somebody else. Don't hesistate to ask further questions about what I'm experiencing, but this is about as clear and crisp as I can put it.

My car is an '07 with about 13k miles on it. No serious mods other than an exhaust, midpipe, and K&N intake.

Sounds like it would only happen if you drive hard...
Try to clean the MAF, check intake connection and reset E-shaft yet?

Do you think it is intake related? My K&N was installed by me and a buddy and I don't think it was installed 100% correctly. It makes this weird "air hissing" noise (it almost sounds like a blow off valve hahaha) and I dunno, I just don't like it anymore. I have a guy here on the forums that might end up selling me his AEM pretty soon; maybe that will help.

Is there a DIY on cleaning the MAF? I've heard people say "clean the MAF" all the time but I honestly have no idea what it is, let alone how to clean it.

And yes, it only happens if I drive hard in low RPMs (when the throttle is more than halfway pressed when under regular RPMs)

Sounds like there could be a leak somewhere on your intake, and cause the wrong reading on the MAF. But I'm not sure, cuz' I got the MS(AEM) one.
Hopefully someone with more experiences would chime in soon, this is just my assumption on the issue.

Google the MAF and you'll know where and what it looks it.
It's easy to clean it, just take it out and spread the decarb on it, let it dry and put it back.
(As long as you can spread it, you don't need to take it out the intake pipe)
Just be careful with it, it's really fragile...

Does your speed change at all when the RPMs are shooting up or going back down?

No. The clutch-slipping comparison is again the best way I can put it. The speed does technically change but it is not affected by the jumping RPMs.

It sounds like a transmission problem to me.... Have you noticed any difference getting the clutch to catch in first?

No, the clutch hasn't changed at ALL. I have made sure of this, as a bad clutch was one of the first things that came to mind.

Yeah I'd have guessed clutch too. If your RPMs are going up but you aren't gaining speed then it sounds like somewhere in the transmission the engine isn't connecting to the wheels. The fact it does fine if you accelerate slowly, or are over 5k RPMs makes me think something might be slipping when speeds change quickly until all the parts are moving at a certain speed... It happens in all gears, right? And are there any unusual noises at all?

You can find a couple of good threads on locating and cleaning the MAF in the DIY section of this site.

the intake noise is a vacuum leak. you may also have a slipping clutch. when is the last time it was serviced?

Not since I received the car in July.

Can you explain to me how this would be a slipping clutch issue? Let me give you a scenario as I was driving today; I was testing the causes of this issue:

-In 4th gear, cruising
-RPMs are at about 4,000
-Let off the gas, down to about 2,000 RPMs
-Floor it

RPMs bounce up to like 5k (much much faster than they should, obviously) while the car is still accelerating and they settle back at about 3.5k and continue going up like they normally would.

I'm really hoping this issue is related to the intake. When I get back from winter holiday I'm going to buy this MAF cleaner stuff and clean out the MAF, might try fixing that vacuum leak too if I can find where it's coming from. Hopefully I'll just get a new intake soon.

it appears that your torque converter is not locking up at high speed the rpm change when you let off gas.
also the rpm jumps then settles means one of the clutch is not working properly.
check transmission fluid condition if its pink and clean, also level if good.

How it could be a clutch slipping issue:..... Because if your clutch is slipping then it isn't engaging properly so you are losing power between the engine and the wheels. If a clutch is slipping it will be the most noticeable when the engine is under a heavy load, like when you floor it.... Basically it just isn't catching fully, so it slips, making it where the rotation from the engine isn't making it to the wheels without losing some of its power.

The described symptoms are CLASSIC, definitive clutch slip.

Alright, so it seems like the general consensus is that this issue is a result of a slipping clutch...

Is a slipping clutch basically a symptom of a clutch that is going bad? The 8 was my first car and my first standard transmission so I definitely abused the hell out of it while I was learning (And I still am learning, really), so I can't say I'm too surprised. What exactly needs to be replaced in this scenario? Would this be an oppurtunity for me to upgrade to a stage 2 clutch or is this not related to any of that?

Typically, repairing a slipping clutch involves replacement of the throwout bearing, friction plate, pressure plate, and re-surfacing the flywheel. Sometimes you can get away with just replacing the friction plate, but if you want it to behave like new and have optimum durability, do all 4 items.

Than, have someone show you the proper way to drive a manual transmission...

Looks like a slipping clutch. Do you notice any smell if you reproduce the symptoms several times in a row? Slipping clutches do smell after a while lol!

Jokes aside, replace it with something similar to the oe unit. An exedy stage 1 will do its job perfectly even in a modded rx8. There's no need to stress the transmission any further.
Also consider getting a lightweight flywheel while you're at it. Resurfacing is ok but a real lightweight flywheel makes a lot of difference ;)
I have BHR's one and at a true 9lbs there's not even a redcution in daily driving comfort.