I'm wondering who has done what with the standard ECU! I have a JDM standard twin turbo FD. It drives excellent with the standard ecu. Mine is the higher powered model. I have owned, built and tuned older rotaries before and frankly the state of tune even after hundreds of hours is no where close to the quality of a factory tune. The turbos change over perfectly, the car cruises and coasts properly starts every time no effort, theres no smoke or smell. The car will coast down hill at super light load at 1% throttle perfectly fine. Its really great and I don't want to stuff all that up with a non standard ECU. So, who has done what with a standard ECU? The car is 100% standard, not a single mod other than a head unit and the fact it has new tyres on it.

The Japanese cars don't have a massive pre cat in the front pipe. The whole exhaust system is only about 2 1/4" however. Everyone I talk to is telling me you simply can't do more than a cat back and an SMIC or an airbox (definitely not both SMIC and airbox with a cat back) without going beyond the limits of the standard ECU. I don't see why the car can't handle a 3" or 3.5" turbo back exhaust with a cat in it and a nice airbox and SMIC. All the Jap cars I look at are making 265-285rwhp on stockish boost levels using PFC's. Considering this model dynos 225rwhp standard... I don't see why the standard ECU can't handle that. Everyone says the standard ECU is tuned excessively rich at full load, around 10:1 air fuel. I think with those mods it should pull it back around 11.5:1 and with colder air and better flow it should make a fair bit more power, up around what a lightly tuned PFC twin car makes on standard boost anyway...

 

What you can do is speculation until you install a wideband.

Do you want to bet your motor on it?

 

I made 295 rwhp on stock 93ecu years and years ago. I've sold around 50 FDs with full exhaust(no cats) and intake on stock ecu. As long as boost stays right at 10lbs you are fine. Any spikes or boost creep will usually spell game over so most let the turbos run off waste gate pressure(7-8lbs) if they go this route. You can easily make 330rwhp with a Pettit remapped stock ecu at 13-14lbs. If you are going to run over 13lbs on the Pettit I recommend water/meth injection. My personal FD runs this exact setup except I still have a cat for emissions. Research, guys have ran mid 12s in the 1/4 mile at 110mph on stock ecu. Some FDs really suffer from 3k rpm hesitation on the stock ecu which is really annoying.

 

sounds like you're experience is with steep learning curve ECU's or just crappy ones all togather. stock drivability is the hardest to tune, and man dyno tunning places only understand WOT.

i wouldn't stay with a stock ecu for anything. i've got an rtek in the fc and a COBB AP in the rx8, both drive like stock, but have the necessary adjustments for upgrades.

 

I own a wide band. I wasn't planning on installing it. Physically very difficult to install one anywhere pre-cat on a standard car because everything is heat shielded.

I don't want this to come out like a flame but that is a really ignorant statement. You're 100% dreaming if you think anyone anywhere in the aftermarket world can come anywhere near the quality of the factory map on the standard car. I don't know how you think some self taught or trade mechanic / tuner can match all the things Mazda learnt about EFI rotaries betwen 1984 and 2002. That is 18 years of OEM backed R&D! The factory calibration is 100% faultless. I can not find a single problem with it and I pay very close attention to the quirky things electrical things do, I work in R&D myself. It is so complicated it has an input pin to measure each and every electrical load in the entire car and feedback into the idle up circuit. If you nearly stall it down to 200rpm it springs back to life, the throttle tip in is excellent. The cold start and hot start are excellent. On the standard car it is perfect.

I couldn't find any material on this stuff sorry, do you have any good threads on the topic? If I'm understanding right you guys work on flow and disconnect the bleeds to the wastegate and precontrol solenoids so that you just get the diaphragm pressures? Does that do anything bad for response? What if I want to keep the boost up around stock (JDM high powered models run 10.8psi), and I'd be happy with 12-13 if at all possible. I can't find any information on where the Japanese overboost cut type stuff is set. I have seen plots for the USDM cars I believe, but my car runs more boost stock than those cars so it would be higher, but I don't know how much so.

 

What year is this car?

I think the best thing to do is install a wideband even if it is a bit more difficult. Since you work in R&D I would think you can appreciate having hard data as opposed to some guesswork and an internet recommendation.

 

Lack of backpressure=oem internal wastegate overwhelmed=boost creep exceeding the limits of the oem map sensor=blown motor.

 

2002, plastic turbos yada yada

Take the measurements before I modify it or after or both? I know 0.78 lambda on premium pump fuel is going to be OK, I'm not sure it matters what the standard oxygen reading is. I'm trying to forge a plan here.

The only easily installed ECU's that run the final version JDM car are

Standard
PFC ~$1100USD
Re-Amemiya Redom Type-A or Type-B ~$1100USD

To spell it out, nothing made for US domestic market works in the JDM car, nothing made for pre 99 spec cars works. The only chip is the Re-Amemiya.

I'm cautious about jumping into this without talking to people that have done this before I can go lay out a lot of money to find out the turbo transistions are stuffed and its a lot of bother to then have to return the car to standard again.

I was sure that there would be plenty of power and E.T. reduction with BPU mods but nearly no one wants to talk about tuning the car on the standard ecu. 12.5@110mph checks out as a nice initial upgrade from standard.

Thanks for your reply. That is always the statement and I am cautious about that happening. So to be clear, what did you personally try and how did it not work? I have personally sat in another 2002 car (PFC + all the common BPU's with a cat installed) and it had no problems running standard boost or even less than standard boost. It was a fair bit faster than my standard car. That car didn't have any waste gate porting yet the car ran a touch less than standard boost on the primary turbo and standard boost on the secondary turbo. The transition was not 100% perfect, it did have a little jerk changing over to both but it wasn't too bad to be honest.

 

You keep arguing that the stock ecu is so wonderful. Thats just not the case. Many of us have had problems with the stock ecu. The 3K hesitation and the overly rich fuel mixtures are two issues just to get started. My car runs much smoother on a tuned pfc. The 3K hesitation is gone. In addition to that, I am getting 3 mpg better gas mileage with the pfc.

I still have my stock ecu. Its sitting on a shelf in my garage. Thats where it belongs!!!

 

re-read that, he's got a 2002 car. my friend is running an FD with the 2000+ spec ECU and its a HUGE step forward from the 92-95 ECU.

 

the number of people in the US that have put a 99+ spec ecu in the car is like 3, like with emissions, you are asking a bunch of people who have never done it before

 

This quote I cant agree with . I have a power FC , and I have one of arghx's maps . which I modified a little bit and my car drove perfectlly started fine , and got better MPG's then the stock tune .

the stock tune runes rich in order to cool the cat and preserve it .

if you eliminate the cat there is no need for that. . My car I could run at 1% throttle like you. and Makes alot more power safely ,

ofcourse there are drawbacks , Like no timing retard from knock . like the oem one But other ECU's out there that do .

and the new adaptronic ECU is basically slapping a state of the art ECU that runs closed loop all the time . with set parameters .

 

Remember Adam and tem120 this car is a 2002 it has a completely redesigned ecu with much faster processing and redesigned wiring. It most likely does not suffer from the quirks of the s6 ecu. Mazda had about 8 years to make the ecu better.

op, I think the best thing to do would be to get readings before and after. But just remember on this forum most of the knowledge is based on the s6 cars which may not applicable to you.

 

I was afraid of the ops concern as well when tuning my car. I tuned the car myself and I am running 650CC primary EV14 injectors. I do have a rich very light throttle going down mountains, and remember I am at around 10,000 ft. I also am rich at 6,300ft but it goes away at sea level. I tuned the car on the street and spent a fair amount of time street tuning the car. If you learn how to tune the car yourself, you can get it to run as well as your stock ECU. you will also know exactly what AFR you are reading at whatever level of load per given rpm. I would think this is safer than trying to guess what the stock ecu can handle.

 

I love the way my car drives with the remapped stock ecu. AC works perfectly, idle is always the same, no bucks on decel and it is simply smoother than any aftermarket tune I have ever driven. I've driven FDs tuned by pretty much ever big name in the industry. With all that said the fuel economy is terrible and the first time I get 3k hesitation I'm going straight to a PFC.

This fall I will be installing 9.7:1 rotors and seeing how the car runs with the Pettit ecu around 13-14psi with water injection. Won't be a street monster by any means but I believe it should have a great power band and slightly better fuel economy all while the engine bay will look completely stock and the car is super quiet.

 

with the PFC you can control the Boost some more you can set the duty cycle of the waste gate at the safe limit . plus different timing , also if hes running a little leaner . remember leaner = more power .(until a point ofcourse)

 

Ohhh I'm sorry i missed that part.

 

If your exhaust is like the 93-95 exhaust, it's easy to remove the stock midpipe (with the cat on it) and have a bung welded onto that pipe between the flange and the cat
That's where my wideband is installed, because I didn't want to take the downpipe off and the cat is so easy to remove :P

 

If you are convinced on using the stock ECU, and you don't want to install a wideband, than keep the mods light and enjoy. The extra 20-30whp you may see with more boost, or another mod is not worth the trade-off of having an unreliable car.

Either take the steps to ensure it will be solid, or don't mess with it.

 

I am firmly with the OP on this.

My 1992 FD runs the stock ECU. It runs faultless, 100% of the time.

I have tuned PFCs for friends and customers who all bought S6-S8 (1992-2001) RX-7s from me.
I have ridden in, been present at dynos, and assisted tune other cars tuned by others, with PFCs also.

Not one of the PFC cars ever ran as reliable, or as smoothly as the stock ECU cars do.

I've also noticed that the majority of the people who come into these forums with the typical "Help, my car's not running right/Why is it doing this/Is the engine blown?" stuff, are running PFCs, 99.9% of the time. Along with a whole host of other supposedly good modifications. You really have to wonder why they are all blowing up. And why I seem to be one of the few with a stock car, that gives no issues, and which I am completely happy to drive, day after day. it does not have the outright power, but it is an FD, and it is reliable and able to be driven without any issues, any day of the year, whenever the mood takes me.

Nobody can get a dyno, sit there for one or two days and map a PFC and hope to drive away with a better map than MAZDA OEM spent YEARS calibrating.

On top of that, you need to understand that the PFC has got NO knock-retard function.
If it senses knocking or detonation, it will flash a silly light at you, and continue indifferently!

The stock ECU will sense knock or detonation, and pull the timing advance curve BACK. This PROTECTS the engine from blowing a seal. It uses the microphone on the side of the block to listen for knock within the right factory-tuned-and-tested frequency, and control timing to keep it from damaging your engine. The PFC does NOT do this, nor can it ever hope to. Nor can ANY of the aftermarket "performance" ECU's ever hope to do it.

You cannot attack modifications on this car in even the remotely same way as a Toyota Supra or a Nissan Skyline, for all the newcomers who simply think that because it is a Japanese performance car, it will be as simple as those cars.

My 19 year old housemate, on learning that I had an RX-7, had this to offer: "Yeah man, why dont we go out there and crank the boost right up on her, like 30psi!! And we'll chop the airbox **** off it and clamp on a pod filter and a BOV!! It'll be wicked cool man! I did that with my R31 Skyline and it cut sick drifts and made 700 horsepower at the wheels man!! Hur hur hur!!"

People like this, when I try to calmly explain that the car has a stock ECU and MAP sensor, and will not tolerate this sort of ham fisted "modification" simply look at me with glazed eyes, and then walk away, thinking I'm some sort of boring killjoy. They sit down and watch Fast & Furious and yell at the tv screen.

I'm not flaming anyone on here for anything. I am offering an alternative path, free of frequent blown engines and the whole PFC saga. Just leave the car as it is. Dont modify it. Appreciate what Mazda put a lot of effort into designing, and look at the elegance of the design. Appreciate how well a stock car actually drives and handles traffic in the real world. It is a stressless car to be in, and it can also perform. It wants you to want to drive it. Not cut it apart

 

Just leave the car as is?????????????????????????

Time for a reality check

My pfc is one of the best changes I have made. In addition to smoother running, and better fuel economy, my car idles so much better on the pfc. The tuneability makes it run leaner. That means less stink, and less pollution (yes I have an oem cat and airpump).

Just leave the car as is?????????????????????????

In the immortal words of John McEnroe:

"you cannot be serious!!!!!"

 

so im still running my stock ECU, along with my stock engine and 93 twin turbos. still even have my air pump for emissions .
mods i have done are
-FMIC kit with greddy elbow
-hks twin intake filters
-3' hks DP
-rx7store highflow cat
-3' blitz nurspec cat back exhaust

- car runs drives great, starts every time, no hesitation . the air/fuel gauge runs lean but not rich on highway cruising speeds.
would a boost controller do the job for now or do you think i would have better luck with a PFC with the mods i have as of now. i havent noticed a boost spike or creep yet either

 

I'd advise you to ask the same question on an Australian forum, they have a lot more experience with late spec RX-7s than over here where the experience is predominately with S6 FD's

But personally - I'll still ditch the stock ecu for a PFC - My FD drove very smoothly on the PFC.

 

Ill add my 2 cent.

Us stock ecus are all 8 bit. Your 2002 is 16 bit. All pfcs are 16 bit.

My guess is very few people have experimented with stock ecu 2002. Also call your wide band manufacturer about putting the sensor on post cat. I remember doing research in this 7-8 years ago and you can do this as long as your car is warmed up and post air pump off, higher rpm.

But to me what you are doing is bit of opposite of tuning an pfc. You are just trying to see what's the max boost you can run on given map which can be dangerous as you have no idea nor change timing. But at least pfc or any aftermarket ecu you can change both fuel and timing as you increase boost. And if drivability is your concern you can dial it in yourself by log and tweak.

Mazda in my opinion aren't as perfect as some of you think. Don't forget that we all live in different altitude and in different air density. They have to worry about reliability and general drivability. But think they optimized better than what you can based on your condition, that's somewhat of a stretch.. Especially if you want to go beyond stock boost setting. I went from stock ecu 93 to chipped to pfc and many different things will also make your car run smoother including my favorite hks twin power.

 

I have been autocross racing and doing the occasional hillclimb, kart track, spirited street driving and road trips for the last couple years with this set up.

1993 49 state model with stock ECU, K&N drop in air filter, Efini "Y" pipe, Stock mount IC, 3" downpipe, 3" "highflow" cat, 3" cat back and most importantly boost controllers on wastegate and turbo prespool for max 10psi boost and perfect transitions.

It did lean out on the wideband from 9ish AFRs stock to low 12s now. But as mentioned by others it has the stock safeguards of factory tuned knock control and conservative correction maps.

109mph in the 1/4mile on street tires.

If you get boost creep or spikes on the stock ECU it cuts fuel which doesn't hurt the engine. My car was raced over 10 years in stock class (catback and K&N drop in) and would hit overboost fuel cut in anything over 2nd gear in cool weather- it never hurt the engine.

I myself reverted it back to stock class and raced/drove it this way for another year, but it just wasn't fun not being able to drive the car hard without hitting fuel cut.

I am interested in an aftermarket ECU like Adaptronic but weary of losing the factory reliability I have had with the car so far.

I am thinking I would rather do a ROM tune if it compensated for the VE change and allowed for 12psi so I could do intake and the boost creep it will cause, but left the rest of the maps etc stock.