I have a 86 rx7 n/a and it has been running perfectly fine, recently i was headed to my friends house and around 3500+ rpms it stared to sputter/jerk and not wanting to accelerate. I think it might have to do with the coils? like its loosing spark? i would try to rev and it seems like there was no power. I let it warm up today, went around the block and and was going 4000+ and no issues, it seems to happen randomly. Any help would be appreciated

 

Check the plugs/wiring for the secondary fuel injectors, and clean/replace all of the main ground connections under the hood.

http://www.aaroncake.net/rx-7/grounding.htm

This may well be a form of the common "3800 rpm hesitation", which can typically be cured by regrounding the ECU. If cleaning of the existing grounds doesn't help, you may need to go that route.

 

The plugs are brand new, just recently checked them, i already cleaned the ground on the shock tower and all others i could find. Is the main ground under the intake manifold? i cant seem to find it

 

The ECU ground is under the intake manifold. There is a ring terminal attached to the rear housing. This is the one that sometimes gets replaced with a new wire from the ECU plugs. Check the FSM fuel and emissions section & wiring diagrams (see FAQ if you need download links), and go to the ECU pin outs. There are 2 or 3 grounds that you can run new wire from.

 

I know on the 89's the ground is on top (lucky). Alright i'll read up on that section and see if i can make a new ground. Btw, my tach went out a while ago, i did a bunch of stuff to get it fixed and one night i redlined the car and the tach started working lol. Do you think that it has any relation the the ECU grounding? Thanks for the help i really appreciate it