I need a bit of advice. I am considering getting an aftermarket programmable computer this spring. I am not familiar with any of the brands, but it appears that there is more activity with the PowerFC versus all others. I assume that this would be the correct choice for a novice.

My question is this. I have a good laptop with Windows 2000 XP. Do I need the Commander to program it or can I just use the laptop. Which would be easier to use?

My goal is a daily driver with no problems. Currently have hesitation problems I am working on, but have been reading that the only way to eliminate permanently is to change the computer.

I have a street ported motor, stock intake, 3" mild steel wrapped downpipe, catback (unknown manufacture, but believe it to be a good name brand type based on previous owner's financial situation), J&S Safeguard.

Any advice would be helpful.

Tim

 

since you are novice i advise you to see a local rotary tuner near you and see what kind of ecu he tunes. in your case you have a ported motor and dp cb, so your motor most probably needs to be remaped, or an ecu because its most probably knocking and detonating, find a rotary tuner as soon as possible the hesitation is because of the porting and earth cables

 

When I said novice, I meant novice to tuning a streetported motor car. I am a very capable mechanic and have been working on and owning RX7's for about 16 years. I understand I am planning to do all the work myself since the nearest tuner I would trust is about 4 hours away.

As for the hesitation, I disconnected the o2 sensor from the computer and tied the signal directly into the gauge. I now have NO hesitation at all between 2500-3500 rpm. The signal stays rich the whole time. I am convinced the hesitation is in the way the stock computer adjusts the fuel to get to stoichiometric balance. This pushes me further towards believing the stock computer needs replaced.

As for the knocking and boost. I am receiving some signal that there is knocking intermittently and randomly and the timing is retarding, but I have not set the sensitivity adjustment on the Safeguard. It is set a bit high for safety reasons. During boost, the A/F meter is showing a solid rich mixture througout the boost phases all the way to redline and there is no knocking during full boost. Since the motor is used (bought with 3500 miles since rebuild from KDR), I cannot confirm internal modifications. The boost drops off from 10 to 8 once it reaches 10psi on the 2nd turbo. It almost appears to me that the wastegate opens up fully or the wastegate was ported to accommodate other mods.

The motor was originally dyno tuned at KDR at 294 RWH with aftermarket intake and intercooler with a PFS PMS piggybacked just before the original owner crashed the car. I did not get those components when buying the wrecked car.

One of the reasons I kept the factory Cat was to help prevent boost creep and lean conditions from occurring. I did however replace the precat for safety modifications reasons.

Thanks for the input,
Tim

 

In order to use your laptop to tune the power fc, you will need the Datalogit addon, which goes for $350 from rx7.com. I would highly recommend it since it sounds like you'll be doing your own tuning. You may want to purchase the Commander also, as it's a nice quick reference for various metrics such as water and intake air temp, injector duty, etc. I would buy the pfc and commander used. I've been seeing them a lot lately on the for sale forum.

If you're referring to the infamous 3k hesitation problem, it completely disappeared when I installed the PFC.

You will need to do some research on timing changes required for your streetported motor, and you'll need a wideband O2 sensor to properly tune fuel. Don't rely on your stock O2 sensor. It doesn't have the output range required to give you very accurate readings.

Search this forum for info from Chuck Westbrook about using the J&S on a rotary. I'm foggy on the subject, but I believe you want to keep a minimum timing split, like 12 degrees.