So I was having some issues with the car running to hot on the hwy.

Not that its related but since then I adjusted my tps and by passed my heater core because it was leaking.

Now it seems that it takes a while to warm up and when it does it only gets to about 1/6th of the temp scale. If I drive it on the hwy way and try to give it some boost (no more then 5psi cus my car cuts the fuel for some reason) I can get it up to 1/4 where its suppose to be.

What are some of the things that would prevent the car from heating up all the way?

 

What are you using to tell how hot it's getting. If its the temp guage it could not be working properly. Not sure what fuel controller you are using but it sounds like your hitting fuel cut.

 

Is fuel cut on a S4 at 5psi? I thought it was like 7 or something? If some one could use a temp laser on the aluminum part of there radiator when the car is warmed up I could compair. I really don't feel like buying another gauge right now if I don't have too.

 

Do you have an aftermarket exhaust without ported wasted gate? If so I bet your hitting 7psi. Even with ported waste gate you can still have boost creep.

As far as temp goes I'd help you but my car is still down so can't run it. But I'd imagine you could let it run for about 3-5 min and pop the hood and you'll know if its normal temp. Especially since rotaries tend to run hot

 

The first thing to do when you suspect cooling problems is get a real temp gauge in the car so you know what your temps really are.
"1/6 of the temp scale" gives neither of us any useful data.