ok i just bought an 86 rx7 and put new plugs and fuel filter,an some additive in the gas tank because it has been sitting..i was wondering why would it cut out at 3500 rpm in everygear?and what kind of oil should i use and is there anything i could put in the oil now?and is there someone that could explain how to tune it to run better?

 

It's cutting out at 3500 rpm? How's the low-band idle?

How much addititive did you put into how much gasoline?

Are you sure you have compression?

 

i would imagine i have compression it runs good enough to take on the high way..and added the right amount...it idles at 1 some tmes more and sometimes less

 

Does anyone have the answer to this? I'm having this exact problem.

 

Likely a grounding problem as it relates to when the secondary injectors come on line (3800 rpm w/load). Could also be a fuel related problem or a clogged catalytic converter.

 

Couldn't be the cat because I don't have one & one of my pigtails on the secondary injectors was cracked & I replaced it. I even bought a new fuel pump & ran additive to see if maybe it was a sticky injector but that didn't work. Can it be spark plug related? I changed the plugs like 4 months ago but I just realized my car is running 4 trailing plugs & not just the 2 trailing & 2 leading.

 

A grounding issue has nothing to do w/the injector plugs itself but has to do w/the ECU turning on the secondary injectors. This grounding issue I speak of is extremely popular as the source of these issues and is very, very easy to rectify (if it is indeed the cause of your problem).

You can unplug the TPS and in addition, unplug the vacuum hose to the Boost/Pressure Sensor and this will place load on the engine such that you can free rev the car while idling and the secondary injectors should work. This helps to diagnose some things. If it free revs w/o load then your focus should be grounding and or secondary injectors.

Fuel additive does nothing to unclog the injectors as this is preemptive maintenance (doesn't help once it occurs). Your fuel sock in the tank could also be clogged.