Hi all, I am new to this board. My name is Simon and im from Quebec/Canada.

I always had turbo cars, but no rotary. I am looking forward to buy one. Yesterday I road tested a 1992 3rd edition JDM one with only 42 000km on it. It looks like brand new. Then engine bay is so clean. It has a body kit, and looks pretty sick with 18" wheels.

The was cas pulling really hard. The guy said that the ECU has been re-tuned by a local Mazda tuner. It's tuned to hit 14.7psi. It has 4" cat back... too big and too loud imo. Other than that, the car is stock.

I was not looking at the boost gauge when I driven it, but the guy said it's hitting 14, and sometime it goes higher, like its spiking to 15-16.

I've read a lot things on the engine, but i want your advice. The tuner said it was safely tuned to run ok. But i've read that the stock ECU (even reprogrammed) and the fuel system cannot maintain if you go higher in boost.

I really want this car, but i am affraid..i don't want to blow the apex

 

 

running at that level the engine will not last for long. The turbos, fuel, and ECU are not made to see that kind of boost pressure. car looks clean, if you get it just turn down the boost and run 10-12psi max.

 

the tuner said the air/fuel was pretty good... grrr

 

Regardless of the what kind of re-flashed ECU it has, the stock twins aren't efficient at those levels. Additionally, your risking the motor on what this guy "says". Your are right thinking that for those boost levels you should also be looking at fuel mods. Ask for some paperwork/documentation on what's been done...either from the seller or the tuner shop.
Depending on what else has been done, it might be boost CREEP your seeing, not SPIKE. Two different things that are remedied differently. But either one can lead to a rebuild.

 

If the engine is good and your going to buy it, you will have to read for hours on this site before you boost the car too much. You can make this car safe for real. Does it pass your government pollution control check? Does it have the cats? Probably not. Probably boost creep. Restrict the exhaust and the sound will be more to your liking and it will be safer. There are many other things you can do to make it safe. read

 

the car looks great. I would buy it then ask the tuner to tune the boost down to a safer level.

 

I really agree with what has been said above. If the wastegate has not been ported and the fuel pump upgraded, then it is safe to say the car is not tuned "safely" as it sits now. Without the ported wastegate it is a known fact you will have significant boost CREEP (and this cannot be tuned for accurately) to the boost levels you are seeing and even up to 17+psi. This is a sure-fire way to loose the motor.

Personally I think that reflashed stock ecu's are a half-assed way of "retuning" a car. It uses a ver broad almost shotgun like approach to tuning instead of tuning for the individual needs of that particular car.

Either way you go, just go get the car compression tested and that will tell you the health of the motor. If it is good, and you buy the car I highly reccommend you turning the boost down and looking into ecu and fuel upgrades if you wish to return to those boost levels. But as also mentioned above those stock turbos will not last long at those boost levels and the map sensor is only a 1bar sensor anyway so you would be highly advised to also upgrade that as well... A 4" exhaust is a bit overkill on the stock twins. Cool on most single turbo conversions but why do it on the twins??

 

I would be very wary of the car as it is now. To safely run 15psi you will need upgraded injectors, fuel pump, and some kind of programmable ECU. Based on the description so far I'm not sure if that's all there.

The boost spikes are not a good sign. Maybe just a minor detail but boost control is paramount.

It may in fact be set up well, and if the tuner knows what's up they'll either warranty it or at least explain all of the modifications and tuning methods used to get the car at this point. If I were buying it and it passed a compression test, I'm immediately dial it back down to 12psi until I was 100% confident that it can support 15psi.