Hey guys ive owned my rx7 for about two and a half years now and i love it but it has its issues.

te motor was rebuilt 20,000 miles ago.

at 3000rpm it will bip but continue to rev up until about 4000-5000 but wont rev past that in gear. If i take it to 7k neutral it will bip randomly all the way through but will go there. The strange thing is it gets worse the higher the gear and the longer i drive. First gear i can use about 80% throttle with almost no issue to 7k, second i can use about 60% with little issue to 7k, but 3rd and beyond it just takes a dump. Its also completely undrivable with the ac on. It has always had the stuttering issue but not to this extent. It became nearly undrivable about 6 months ago. Luckily its 90% fine under 4k so i can still daily it.

Everyone (local rotary enthusiasts) keeps saying its fuel or ignition but ive recently replaced the fuel pump and filter with no success and have used confirmed good coils off of other peoples cars (cables are new from the rebuild). Ive replaced the spark plugs twice. Considering it gets worse under load and with the ac i disagree with them, from what ive read over the past few months i think its bad grounds but everyone looks at me like im crazy when i say that.

Heres the video. https://youtu.be/FoKnNjpZTUc

Its hard to see the needles but it does exactly what i described in the post.

I really hope you guys can help me get to the bottom of this, i havent been able to do a solid pull in my car in ages and im tired of losing traffic position to litterally everyone.

 

What kind of FC do you have?
Have these issues been present since the rebuild or are they new-ish?

Bad grounding is not an outlandish theory and not expensive-except in labor/time- to check out.

 

Ive always had a "bug" but it has gotten really bad in the last 5 months.

 

Has the cat been looked at since the car was manufactured?..?..
aux ports functioning?

 

What is your voltage gauge reading when the problems are the worst? Should be about 14 volts.

 

No cats. Im manifold to 2.5 pipe to 2.5 magnaflow muffler.

Air pump is blocked off.


Idk wgat they're called but we pulled the intake "valves" out.

 

I havent watched it personally but my buddy said it was solid. Ill check it out tomorrow.

 

Did you have the injectors reflowed/rebuilt when the engine was rebuilt?

 

Check the oxygen sensor too.

 

Check the oxygen sensor on the exhaust manifold. If it's ancient, replace it.
Check the engine grounds. -> (Proper RX-7 Grounding Procedures)
Adjust the TPS with a multimeter. -> (FC3S Pro v2.0: TPS adjustment)

The air pump sounds curious, how exactly did you block it off? Also, what do you mean by intake valves? Are you referring to the AFM or the throttle body?

 

Maybe 5th and 6th port sleeves?

 

I'm a little surprised at a few people here...

My 87.5 gxl had the same symptoms when I had a secondary fuel injector suddenly fail. Take your meter and ohm out the secondaries..

For grins and giggles you may want to ohm out the others as well to determine whether or not they may be getting on as well. My other three injectors were fine.

 

My vote is secondary injectors as well. I had a primary injector fail on my car a few years ago, but it was intermittent. It would run fine until you looked at the car funny and all the sudden you where on one rotor, once you battled running on one rotor until the secondaries kicked in, it would start running fine again, and you could drop back down to only primary injector rpm and it would be fine or not.

It was funny when I got the car towed because I started the car and it ran fine. Tow truck driver wanted to drive it up to his truck to get a good aim for the bed and as soon as he stepped in the car, the car said "no get out!" and ran on one rotor. I got in after he got out, cussed the car, and after putting it in reverse, it started running fine again. The tow truck driver quipped "Your car doesn't like me". Had RP throw the injectors on the tester and sure enough the rear primary would intermittently fail, which is rare because injectors usually work or they don't.