It's been doing this lately,and when i take my 7 on the interstate and punch the gas,and when i'm close to 100 i get small sputters in the car then i get a loud wierd sound out of the exhaust and it boggs and this around 100 mph.I slightly under 10 lbs of boost and the rpms around 5k. i have a straight through exhaust with HKS PCM FCON fuel chip.Is this a fuel problem or possible turbo,cause i'm having problems with my primary turbo.My mechanic can't figure it out,he can't take my 7 that fast around his shop.Please help,it sucks owning a 3rd gen rx7 and can't go past 100 mph.

 

What gear/rpm are you in at 100? Sounds like you're hitting the fuel cut early. Be careful or the motor could pop. That would be odd if the car had a speed governor installed and set for 100mph.

 

Well it's an auto and it's in drive and the rpms are between 5 and 6K

 

Fuel cut. watch out.

 

It may be the fuel cut, but why the hell would the fuel cut be set at 100 mph. That makes about no sense at all.

 

an auto at 100mph & 5500rpm is still in THIRD - and should be upshifting to 4th! my Auto only turns 3500rpm for 100 in 4th, may be an ECU prob - try resetting by disconecting the battery and pressing the brake pedal.
Are you sure of the BOOST fig? - if you are running a dp & mp you may be getting more like 14-15psi at 5k rpm in 3rd and are hitting the boost/fuel cut

I have gotten 14psi spikes (and hit fuel cut) on some COLD mornings see sig for my mods

 

when is the last time you changed your plugs? does the sputtering happen at high rpm all the time or just near 100? I'm not familiar with the fcon, but I believe it removes the fuel cut, or perhaps you need the fuel cut defencer. Are you at WOT or have you tried to ease past 100?

 

fuel cut is set by boost, not mph

 

silver flash
just get a fuel defender from hks
its worth it you dont want to blow-up

 

Yeah i can ease past 100 mph,it's just when i WOT. have a boost leak,but with this colder weather i can get 10 lbs of boost.Normaly i'm at 6-7 lbs under wot.I have a fuel cut defencer,but i know that this isn't normal and thought i'd wait to put on the defencer.What number should i select on the defencer 0-12.Not sure how to tune it.Or if this is my problem.

 

what about WOT at lower speeds-do you get the high rpm breakup? you never answered about the plugs. could be those, could be fuel cut. it happens pretty low at higher rpm. could also be the fuel filter. look around at these: https://www.rx7club.com/forum/showth...ight=boost+cut
Nevermind, I see you started a lot of the threads I was going to reference. As a start I would change the plugs and wires if you haven't already.

 

ps for the retail on a HKS PFC you could have got a Apex PFC.