Hey guys I have some questions I was wondering if you guys can help me out. Well I went to check out this sweet looking 93 RX7 today and took it for a test drive. The car has a new streetport engine 7k miles, New turbos replace about 10k miles ago, PF intercooler, PF exhaust system, and PF piggy back. Well when I test drove the car the engine sounds smooth and idle just fine. But when I start to roll along in 3rd gear I notice the hesitation at about 3k rpm. So after I noticed that, I try to punch it harder to see what’ll happen. Well I was in 3rd gear at about 2500rpm I floored it to all the way to 6k rpm, and guess what? I saw the boost gauge jump to 16psi when I floored it at 2500rpm, down to 10psi at about 4k-5k rpm and up a little after that to 6k rpm. And during the entire time it was hesitating in like every 1000rpm like the fuel was being cut-off or something. So would you guys know what is happening and how to fix it at all? He doesn’t have a fuel cut-off so do you think that might be the problem when boosting more than 12psi? And is it safe to be boosting that much without a boost controller? And is it normal for it to boost that high with just those mods and no boost controller and just a piggy back system?

 

If it's "hesitating every 1000 rpm like it's hitting fuel cut or something" when accelerating, there's obviously something wrong with the car. Very doubtful that the problem could be diagnosed when it's not your car and you don't have access to it. I'd look elsewhere for an FD.

 

would you know why though, or have a good idea of what it might be. Do FD's have to use a fuel-cut defence at all like the TII to get rid of that fuel cut-off point?

 

You can't just use an FCD like a TII - the boost sensor is also the primary airflow input to the ECU. You have to do it the right way with an ECU - either a chipped ECU or a PowerFC.

But, with the PFS piggyback, you shouldn't be hitting fuel cut. But, it does look like the car will need some work to get 100% - you'll be going behind someone else's work trying to debug the car. It could be something incredibly simple, or something very labor intensive and time consuming to sort out. I would make sure that was reflected in the price of the car!

Dale

 

A car that is acting that badly must mean the owner didnt take care of it at all. Dont waste your time even thinking about it. Just move on to another car. There are plenty out there.

 

The PFS ECU has been known to be overly sensitive to the knock reading. The typical fix is to move the knock sensor to the rear housing which keeps the PFS from going crazy.

That's what it sounds like this car is doing.

 

I seriously doubt there is anything wrong with the car. I used to have a PMC combined with a PFS IC, Cold Air, cat back, etc... At one time, I had the same problem.

I would be willing to bet the tuning on the PMC is just screwed up. I suggest going back, unplugging the PMC, and just run it with the stock ECU. That should clean up the problem. Then you'll know if it's the PMC or not. Also, make sure to give the ECU time to relearn.

The 3K hesitation is very famous, and been discussed at length. Everything from adding ground wires, to reseting the stock ECU, checking for leaking injectors, etc.. can be tried. People have different luck with different things.

Your problem, though, I bet, is the PMC. Since it hasn't been said yet, I'll say it.

Go to the used section and buy a profec B, set it to 10 psi.
Put the PMC up for sale for like $200-300.

If you really want to boost more than 10psi, get the PFC. Then, either buy a wideband and read about tuning, or pay someone to tune it for you.

 

If you read his post, he's really getting it at about every 1000 rpms.

 

Yeah, my reply wasn't clear.

I didn't mean to confuse the hesitation problem with the mention of the 3K problem.

I still believe the surging and hesitation problem every 1000 RPM is PMC programming related.

 

Thanks guys for every details that was reply. Now i can't really test it out or try to fix it in any way because it is not my car, and if it is that simple and simply by fixing it i can't really reduce the price of the car :-) so good for me. Now the price is set at first for $14500. i got him down to $13500 i told him soon or later the 5th gear syncro will go and i have to rebuilt it and it will cost me alot and also the left side fender has a dent in it so thats how i got it down to $13500. But with this problem exist how much do you guys think i should offer or how much do you guys think it is worth in it's condition now. And here's the link to the car so you guys can check it out and tell me http://angrycamel.com/gallery/93_RX7_For_Sale

and by the way what is PMC?

 

That's the PFS/EFI ECU.

 

Looks like a pretty good deal - especially with the new engine.

 

That's like..."The Rotary Owner's Creed"...or something

It's always either a big, labor intensive problem.. or sometimes you get lucky and it's something simple like:

Seller: "oMg tEh cAr StArtZ riHgt uP bUt StutTerRzz bAd. $200 bUx 4 iT?"

Me: "$200 bucks for an FC? OK, I'll buy it."

Spark plugs + Spark plug wires later...

Car runs perfect.

That's why I now own a nice, clean, 100% running '87 GXL now for $200. lol

Point:

Always check for the little stuff. Spark plugs, oil, fuel-filter, etc.

 

I just went through the photos of the car. First off, the Autometer boost gauge will have to go. It's reading over the zero "box" with the car off, so any boost reading you see on it is too high. That explains why the boost was hitting so high.

The car is a mixed bag. It most likely has been tracked, with the Wilwood brakes and stuff on it, so there may be some hidden issues with the car. The damaged fender is also something to consider. But, the car comes with quite a few good mods, the mileage is low, etc. Not to mention it comes with a stack of wheels!

The PFS PMC is a piggyback fuel computer. It was *the* computer for many years until the PowerFC came out. I'm with the above - get a boost controller to keep your boost in check, sell the PMC, and save for a PowerFC (which is about $800 or so). The PowerFC is a FAR superior fuel computer, fully tunable, and the car runs great with it right out of the box. It even eliminates the 3000 RPM hesitation .

Just be aware of what you're getting into. If you're a novice mechanic and don't have money to pay someone to fix the car, look for something closer to stock. If you're a good mechanic, don't mind spending time studying and learning the car, and can fix the quirks it has yourself, or you have the money to pay a rotary specialist to get the car 100%, go for it. It's a tough call. Remember, there are plenty of good FD's out there, especially if you're willing to drive a bit to pick one up - don't bite at the first car you come across!

Dale

 

thanks a lot again guys. now i did owned 4 fcs now and did a lot of work myself from swapping engines to changing brakes, but i can't say that

i'm a good machanic or an expert, but is that good enough to own a car this complicated? And by the way what do you guys think, this car with problem(s)

for that price or a little lower or the S2000 i just found locally. it's a 2001 Silver S2K with only 37k miles original for $16900 now thats really cheap for

the price and hopefully nothings wrong with the car. Well it's a dealers car so i hope not. So what do you guys think? i know its not an RX7 that we

love but it's so freakin cheap as Sh!% may i say. So i need your opions guys.

 

You're looking at a car which is a 2001 versus a 1993. It's a Honda (which any mechanic shop can work on) versus a Rotary (which requires regular forum consult). You can probably still get a decent extended warranty for it.

I think you'll find most people here put up with the BS of the mazda because they love the car - and there are plenty who love the car, and drop a V8 in it, or just sell it and get something else.

If you are worried about the problems, don't have time to mess with it mechanically, and don't just flat out have to have one - The S2000 sounds like the way to go.

my opinion, for what it's worth.

 

WEll thanks very much guys, problem solved. I just pick up the 2001 S2K for $16000 with only 37K miles on it, Perfect condition drive smooth so thanks again.

 

congrats - post some pics!

 

sure will coming soon

 

Here it is guys

 

Some More

 

Last two and let me know what you guys think ok thanks

 

Very nice! Get some aftermarket wheels and you'll be all set. Congrats!