Decided to upgrade my 1993 RX-7 with all the latest goodies. Am regretting it big time!! Here is a brief list of the new add ons and at the end I will describe my problem.

New adds include: Blitz intercooler, Greddy exhaust, Greddy pulleys, downpipe, boost controller, boost cut controller, intake, B&M ignition, MSD plug wires, and a HKS f-con.

The end result: a car that does not run. HKS recommends a setting of "3" for the f-con. The car will not run over 4000 rpm without it starting to sputter and die. It feels as if the plugs are flaming out (losing their spark) due to excessive fuel. If the f-con is unplugged the car runs better but still dies out at 5500 rpm (begins to sputter again). Boost is set at 12 lbs.

The question: Is the f-con conflicting with something else which is causing it to dump too much fuel into the system? Even without the f-con hooked up the car runs better but again begins to die at 5500rpm. What would cause this?? The f-con was even sent back to HKS to be tested and returned with a clean bill of health.

Some of my friends are suggesting the possibility of leaky vaccum lines. Could this be the culprit? I am open to as many suggestions as any of you have! Thanks in advance.

 

Almost 30 of you looked at this post and no one had a solution?? Here is the latest. Disconnected the fcon today and the car runs perfect. F-con was checked and re-checked by HKS and works perfect. It just doesn't work perfect on my car.

Has anyone else had a problem with the F-con? To be on the safe side I have turned the boost down. Full acceleration to 0.5 bar only. Want to actually enjoy the car for more than a day and then see if there is another solution.

Still would appreciate some insight if anyone cares to comment.

 

The stock ecu cuts fuel to rear rotor @ 12>14 psi boost - Is the Fcon properly wired to defeart this?

 

You are supposed to mod one thing at a time so you can go back and trace the problem if something is wrong.

 

Jeez you're modding like crazy! What djantlive said.

Sounds like you're hitting fuel cut....hitting it @4000rpms is not a good sign...you're probably getting near max injector duty cycle and they are sticking open or closed. I wouldn't push the car hard right now if I were you.

You should start doing fuel mods...fuel filter, high flow pump, fuel pressure regulator, and most likely youll need larger injectors as well

 

Sounds like a fuel problem...maybe before you do anything you should take the car to a quailty rotary mech or shop...Wouldnt wanna go through a motor.Not to mention it might be something very small and dumb so dont waste ur Cash on anything till u get that puppy into a shop! But what do i know afterall i own a stang

 

Is your wastegate ported? No problems with creep? How high are you boosting?

I agree with the above posts, you are hitting the fuel cut.

I hope you get it worked out. Also I recommend doing one thing at a time, it is much easier to trouble shoot.

Mike

 

First ... thanks to all who took the time to reply. It seems like the consensus is a fuel related problem rather than an electrical related problem.

As I mentioned I disconnected the fcon yesterday and ran the car. It ran like a champ. I kept the boost low to be on the safe side.

Where should I go from here? It sounds like I need to upgrade the fuel delivery system. What should be done first? Injectors, pump, regulator, etc? I know I sort of jumped into the mods quickly but I did not figure things like the exhaust, pulleys, air intake system, blow off valve, intercooler, etc. would lead me to experience the difficulties I have been experiencing. I guess I was wrong.

The question remains ... where to from here? I want to hook the fcon back up so I can run more boost. How do I prevent it from sputtering at 4000 rpm? Thanks again everyone!

 

I think you would have been fine, sans the intercooler. Most people I know who upgrade their intercoolers get some kind of fuel mod to match it as well as porting their wastegate to prevent boost creep. I would pull out the injectors and get them flow tested to make sure they're not clogged. If you're still on the original fuel filter, I would get that changed by someone for 100 bucks or just DIY if you have the patience.

 

I think you should dump the f-con, and go for either something like an M2 or pettit ECU, or a PFC or PMS.
go ahead and change the fuel filter, change the plugs and clean the air filter if it needs it.
you should be fine after that.

 

Get a Power FC, now. In the power fc section there's a group buy going on for a great price (~$1k for the ecu and commander). Barring that, use a Greddy Profec B to control boost. I love mine.