car bugs out around 3k rpm if on wide open throttle!! help
 

hey guys!
i have an 87 rx7 13b n/a
i recently bought the car and it was stock except for the short shifter, an intake, and a custom exhaust that has no cats or pre-cats. its just a straight pipe (3 inches) all the way back and splits in 2.

When i Wide open throttle on the car it bugs on like if it has no fuel it does this from 3k to 7k rpm.

they also had a block off plate on the side of the engine where I'm guessing an airpump went there or something that had to do with the 5 and 6 port.

can anyone please help me? its driving me nuts and i have no one here in Florida that knows anything about rotorys!

thank and happy holidays!

Sounds like the auxiliary ports are not opening. If they completely re-did the exhaust and removed the catalytic converters i'd assume they also removed the split air pipe since it was connected to the main cat.

If you want a quick fix i'd suggest wiring the auxiliary ports open. You will lose a bit of low end torque (:lol:), but you will not "bug" or bog down in the top end as much. Another fix would be to get a header from racing beat with a pickup tube that actuates the ports, or just put the main cat back on and run the split air pipe.

you have a picture of this split air pipe?
i tried keeping the aux ports open and the car runs like total crap.
so forget that it wont even stay on.
i notice that if i only put half throttle the car dosent studder like it normally does. is this still the ports?

It's dark right now, but I can go and take one in the morning for you.

If you just recently bought the car i'd do a tune-up if you haven't already and see if the issue still persists. Also, check the throttle position sensor and timing.

ok awesome please try not to forget.
umm yea i bought the car not too long ago and i immidiately did the tune up. made sure the sparkplugs were in the right place and everything.

i checked the tps and the tps came back good. the timing i will check tomorrow. lets see what happens.
i saw today (changing the oil) that when i open by hand the 2 butterflys (throttle plates) on the top of the manifold the car studders and back fires like crazy. is this normal on idle?

the car revs up just fine. just dosent run right.

have you checked your grounds?

no i actually havent.. i'll do that today...
i got moped by a honda civic. automatic thats how bad it is.. ;(

Non-turbo rx7's aren't fast by any measure. You should probably do a complete tune-up, verify your TPS has no 'blown open' spots in the resistance. Clean/fix grounds, and also check/clean your secondary injectors. That'll usually resolve just about any 'bucking' or WOT issues, unless perhaps you have a severe vacuum leak.

i checked my tps and its checked out!
the ground seem to be good but i have no clue if im missing any...
as for the secondary injectors... im going to have to take it all apart this weekend.

ok for some reason if rx7's don't have any backpressure on the exhaust they'll not open the secondary injectors. i noticed this when i had my N/A and i only had the precats on, without a cat or catback, i reved up the engine pass 3k rpms and it immediatly died. maybe having such a big exhaust has something to do with your problem guy, you don't want such a big echaust on an N/A i think 2 inch is more than good enough