I got a 89 rx7 n/a my engine starts to run rough and hesitates at around 4000 rpm. It feels like it's miss firing but I don't know

 

you could be fighting ALOT of things, firstly, is the car all stock? what has been done to it recently? Has it had a GOOD FULL tune-up recently? if not, start there, and look for vacuum leaks while your at it

A good full tune-up is the basis for ANY problems that are beginning, along with finding/fixing vacuum leaks, if not, all you do is chase your tail

 

It's all stock...pulled the plugs look good wires are fairly new oil still look good

 

make sure that ur trailing an leading plugs are in the right orientation

 

It happens mostly at full throttle

 

How would I know that

 

Leading plugs are the lower spark plugs while the trailing are the upper. The coils have a number on them where the plug wire goes. 1 means front rotor and 2 means rear rotor. Also, it appears you have a secondary injector issue as they come on line at 3800 rpm. If you can slowly creep through this level but the engine falls on its face when you try to stomp through this level then chances are it is the secondaries. They could be clogged, they could have a poor connection w/the injector plug or the main engine/ECU ground is poor.


Also, has the car always behaved this way or what?

 

Thanks...I figured it out the wires were in the wrong place