hi all,

i am travelling to pick up my '94 RX-7 in 2 weeks... i can't wait! it was set up a few years ago with a TON of Pettit parts (complete 3" exhaust - DP/resonated center pipe/RB cat-back, ECU, lt wt. flywheel, pullies, cold air intake, etc. etc. + suspension).

i had the owner trade out the 3" Pettit center resonator for a Bonez HP cat last week. the tech had issues with the idle and ended up opening up the Pettit ECU to 'pop' in a new chip - whatever the heck that means! i believe that the Pettit chip inside the ECU was traded for a more mild Pettit chip... does this make sense?

anyway, i'm feeling that the Pettit ECU is a bit outdated technology wise and that i should just pull the trigger and buy a PFC. what do you all think? is this the way to go? are there better options for my set up?

is it as simple as sending the vendor a list of mods so that the PFC can be 'mapped'? i understand that i can get two tunes. ?? why?

thanks for the input. i have 'searched' but my thread is a bit more specific to my car.

regards.

 

First of all, this isn't like chipping a VW or reflashing a WRX. What that does is retain the driveability of those factory ECU (which are much more powerful than the stock FD ECU) while making some changes to fuel and timing to make the engine safer and/or more powerful. The Power FC replaces the factory computer with something that is more adjustable but not optimized for perfect driveability out of the box. When you give a vendor a mod list, they will essentially send you a map that will hopefully keep your car from blowing up. That's all you should expect from a mail-order tune.

You can "get away with" just a PFC and a pre-loaded tune. But optimum driveability comes from

1) a knowledgeable PFC tuner
2) street tuning
3) an on-board wideband hooked to a Datalogit laptop interface box

I consider "optimum" driveability to be what you would expect from a car off the showroom floor--a stable idle that doesn't stumble or surge, maximum throttle response without bucking or hiccups, no hesitations while accelerating, and a tune that is leaned during cruising for fuel economy and a reduction of carbon buildup.

The Datalogit box gives the user laptop access to the PFC so they can save and load maps, access a number of hidden driveability settings, and log AFR's directly into the tuning software (as opposed to looking at a dyno wideband and guessing what to modify).

If you really want the car to run well for the long term, the best thing to do would be to get a used PFC+Commander (they hardly ever fail as long as somebody didn't fry something through a wiring mistake). Buy a brand new wideband (I recommend PLX or Innovate, stay away from AEM). Then get a Datalogit, used is fine as well. From there you can look online and load a safe, somewhat driveable basemap on your own. Hook the wideband signal output to the Datalogit and confirm that it agrees with your display. Now any worthwhile tuner has his own Datalogit, but if you have your own and get it hooked up to your wideband you will make his job much easier. I wouldn't expect a tuner to go and wire up your wideband to his datalogit for free; he'll just try to work under the crappier conditions and might be forced to cut corners.

With the wideband hooked up though he'll be able to drive around with you and make logs of the AFR during any stumbles, hesitations, or other problems you may notice. He'll be able to more quickly and accurately adjust your fuel maps on the dyno. And if anything else comes up after your tuner goes home, you can make some logs and post them up here for other people to look at so you can make a change for whatever reason. A properly configured Datalogit is a long-term investment in the health and driveability of your engine, and it's no coincidence that the best tuned cars have one connected to an onboard wideband.

Again, technically you could buy just a used PFC + Commander. Then just reset the thing and run on the Apex'i basemap and you'd probably be ok for a while if you don't have too many mods, or you could even throw some fuel at it with the Commander.

 

wow - thank you for the a very complete and informative response! i understand now... trouble is ~ i'm not a very technically savvy guy. i will need to find a good shop in the Washington DC metropolitan area to set up my tune. i've been in contact with PBCautomotive in Chantilly, VA. they seem like they may be up for the job... big Mazda Club guys.

thanks again!

 

Talk to their customer base about tuning ... proof is in their results, not their talk.

 

I actually had the petit unlimited ecu a few years back and was running dangerously lean on stock turbos/boost w/ straight piping throughout and intake. Luckily I never ran it hard (few months on local streets on weekends) until I upgraded to my pfc and wb

IMHO the powerfc (or any programmable ecu) w/ a good WB and tune are the best mods I've done (other than radiator lol). It sounds great...like a tuned car lol and is running great, not a garbage disposal that backfires every 5-10 secs.

BTW congrats on the soon to be purchase!!! =)

 

good advice... thanks! can't wait for the trip home -

 

looks nice!!!

 

very good condition man, especially for a red interior. don't go hacking it up. it is more rare, valuable, and impressive to have a relatively stock-looking interior and exterior in good shape

 

thanks... and agreed. i specifically sought out a '94 SSM/Red Touring model that had super low mileage and was in stock form. i quickly discovered that there just were not any out there in this color combination (i know of 3 now). when i stumbled across this one with mods and higer mileage - BUT with excellent history and overall condition - i jumped on it. it was set up for auto-x and has coil-overs, flywheel/counterweight, pettit stuff, etc. but the cooling reliability upgrades were passed over for some reason.

i'll leave the 'look' all stock - nothing to the interior... will add an OEM R1 front and rear spoiler - that's it.

thanks again.

 

No that doesn't make sense. Changing the cat should not have had that much of an effect on the idle. Vacuum leaks or a blown motor effects idle. Have you done a compression test? How much vacuum does it pull at idle?

The Pettit ECU does work well for the mods it is designed to work with. Its a pretty safe/rich tune as far as I understand so long as you don't surpass the air flow mods that the tune was programmed to handle. They aren't re-chipped so someone is blowing smoke up your *** there. Be wary, ask the tough questions.

The PFC is a great standalone but you need a great tuner to really realize any benefit (compared to the Pettit ECU) from having a programmable standalone. Tuning ain't easy. I wouldn't trust that shop you mentioned as far as I could throw them w/o seeing many results. There are very few good rotary tuners and someone with as little knowledge on the topic as you do will probably not be able to determine who is blowing smoke and who actually knows what they are talking about. No offense.

PFS is a good tuning and rotary shop in your area. Look in the Regiional forums for info on them.

Good luck.

 

If I may offer my opinion.. I would suggest you speak with the guys at PFS (Peter Farrell Supercars) in Frederick. They have been around the rotary scene for a LONG time and are very good at what they do, they are a bit pricy, but worth it. You may wish to PM ErnieT here on the forum, he's got a MONSTER 7 and, I believe, had almost all the work/tuning done there.

Traveling a little ways for a good shop should not be out of the question, as the results will be well worth the trip. I used to drive 3(ish) hours from the middle of England, down to Portsmouth, to have work done to my car that I wasn't comfortable tackling on my own..

 

i was communicating with PFS for a minute, but they seem really busy. i was trying to get them to fabricate a SMIC but was not able to finalize anything.

another member here suggested RP Performance at Summit Point Raceway, WV.

http://www.rpperformanceracing.com/Default.aspx

so far, they've been great to talk with.

 

Why would you fabricate a SMIC when tere already are so many available off the shelf?

RP is a good place also. They've been around for years.

 

yeah, crazy right? it just sounded to me that PFS doesn't have new SMIC's in their stock and they are made to order. i could be wrong.

in the end, i just bought one from Pettit.

 

Good choice. Got the car yet?