Check engine turns on in 5th gear.
 

So my check engine comes when I am in 5th gear right above 3000rpm's. car doesn't seem to sputter or anything just keep going like nothing is wrong. Also the temp. On the car is about normal maybe just below midpoint on the gauge on my cluster. Ask my instructor who owns about 3 rx7's all he could say was that its weird. This only happens around the described conditions if I push in the clutch the check light turns off. I have no idea what it could be and neither do any of my teachers at my tech school. I'm assume its something with the gears but that's with limited knowledge on them since we have only gone into depth on brakes so far. :scratch:

Check codes: 89-91 CPU Trouble Codes

The temp gauge on an S5 is nothing more than a "warning light" with 3 settings:
1) Cold
2) Warm / Operating temp
3) Rebuild

The S4 water temp gauge is actually linear and useful.

Would it still flash a code if the light isn't on? Cause once I push the clutch in it turns off.

You still need to check for codes and your problem might be TPS related as the throttle linkage fully releases from the TPS plunger rod at close to 3000 or so rpm.

My throttle body is sounding like it might be the problem, replaced it recently might of did something wrong while putting it in. I will still check for codes.

i was just doing research on my s4 manual trans and there is a "5th gear switch".. i have no idea what it does or what its used for but that might have something to do with your problem. Ask your teachers what this does.

It activates the Split Air Solenoid in the ACV.

what kind effects happen when the Split Air Solenoid in the ACV does not activate? poor fuel economy? lower power? if anything?:scratch:

I believe it affects the level of emissions released through the exhaust.

It opens when cruising in 5th gear to allow more air to the main cat. But there is always a small opening that directs air to the cat when the ACV is not switched to either direct air to the exhaust ports or dump it out the relief path (open air).

The 5th gear switch also prevents the shift-up light from coming on in 5th gear.