pistonssuck

If I put a intake, downpipe, high flow cat/straight pipe, and a cat back exhaust on my factory FD ecu will it cause overboost or any other problems to the motor or turbos?

asianguy02

iTrader: (4)

good chance you'll pop the motor there. Depending how patient you are, you can fab up a home depot boost controller for $20, or you can pick up an electronic one for $400. Rob Robinette has a great example of the home depot one on his site, check the FAQ, or you can do a search and find member reviews on various EBC's available.

Regardless, search next time, this question has probably been asked hundreds, if not thousands of times.

djseven

iTrader: (56)

A boost controller will not prevent boost creep. To be truly safe you need to remove and port the turbos. For years I have been running full exhausts on fds on the stock ecu with the boost restrictor pills removed from teh pre-control wastegate actuator and most important the wastegate actuator. This will start to open the wastegates at 7psi of boost and should let the car only see around 9psi towards redline which will be safe.

If you are seeing over 10 psi of boost even if just towards redline for a second this is dangerous and you should port the wastegate or reinstall the stock catalytic converter.

arghx

iTrader: (3)

If the wastegate can't flow enough, it can't flow enough and no boost controller will fix that. I'd run a cat to be safe.

baggedoutmazda

you should just spend the time now to port the waste gate as these mods you are installing will be the 1st of many.

cptpain

iTrader: (1)

before installing those mods, i think you should invest in a PowerFC and at a minimum, some larger secondary injectors.

if you're planning on staying twins, i recommend getting the BNR stage 3's sometime down the road.

gracer7-rx7

iTrader: (16)

Those mods are fine so long as you keep boost controlled to 10 PSI. That is all the factory fuel system supports.

Turbo rotaries often need back pressure to help regulate boost especially when close to stock (vs single turbo) so keep a high flow cat or stock cat in there.

The high flow cat can lead to spike/creep in winter weather so be careful there. A boost controller only helps so much but I have had good luck in NY winters when using a cat and an electronic boost controller.

See threads in FAQ and Archives for past info on this topic.

oo7arkman

iTrader: (2)

^^Bingo, as long as you are keeping to 10psi or under you should be ok. But like mentioned above with what you have done it is highly unlikely that you are only seeing 10psi.

Enervation

I've always been under the impression that using the stock ECU and substantially increasing flow (whether it be via intake, downpipe or catback etc) and maintaining the same boost pressure (10psi) is not safe - but this is more of a question than a statement, so please correct me if I'm wrong. My understanding is explained below.

The factory ECU seems to be tuned to somewhere around 10.5-11 AFR at stock boost & no mods.
Now say we add an intake, downpipe, catback, and remove cat, we have increased flow (and keeping boost at 10psi), to get say 280whp - an increase of approx 50hp, or roughly 20%.
As the ECU is MAP based (as opposed to MAF), then it is unable to detect the increased flow, and would still be delivering the same amount of fuel as if it were stock. As we are flowing 20% more air, then the AFR will have increased to around 12.6-13.2, which is I've heard is getting into unsafe territory.

I understand this is one of the flaws of a MAP based system - any flow mods require a re-tune, whereas a MAF system is able to adapt to changes in flow.

zxrazorxz

imo is to figure out a map for modification for your car.. like.. if eventually your planning to go single.. get the supporting mods and keep the car stock untill you get to that end goal with ease.. also make sure you have a good running platform before you modify.. or you will be hunting down problems in the future. but to awnser your question like so many others have yes it will be too much for the stock ecu.. so imo invest in a standalone before you modify anything.

matt

MrNizzles

iTrader: (5)

I have same understanding as Enervation ... air flow mods change air fuel ratio, regardless of keeping 10psi .. right? I should hook up a wideband on my stock setup and see what afr's I'm getting. Does the PowerFC keep track of afr's if a wide band 02 sensor is hoooked up? sorry don't mean to hijack, but the op might want to know too

zxrazorxz

the pfc can only if it has a wideband o2 sensor.. narrow band act as if everything was ok until it reads a voltage difference telling it that is lean or rich. its really not very accurate and only runs under warm up i believe? anyway a power fc keeps track of afr through a wideband and it can be displayed on the controller. other then that.. the obvious is that it is a standalone computer and will let you get the hosrepower one wants while doing so safely with user defined settings, such as fuel maps and ignition maps

gracer7-rx7

iTrader: (16)

We were all under that impression until someone dyno'ed a modded car with the stock ECU. There is a thread about it somewhere on here. I tried searching for it but am out of time. Here is a link with the beginnings of some info on the topic:
https://www.rx7club.com/showthread.p...no#post4329188

You guys are welcome to research it further.

If someone does find that original thread and the dyno, please PM me with it so that I can include it in the FAQ thread.

Anyone that finds the original thread gets a cookie.

j9fd3s

iTrader: (3)

i think i can answer that. i dynoed my FD a million years ago, very mild car, at the time it had the 96+ intake and Y pipe, 3" downpipe, and it may or may not have had a cat back at the time of the dyno (i'm thinking it didn't)

i do recall that boost did 10-8-10 and then dropped off, by redline it was probably boosting 5-6psi? afr was way rich as i recall, maybe like 10:1?

anyways, if say you added a midpipe+catback, maybe it now does 12-15-12 and drops off to 10psi by redline, in which case the ECU does see that

Speed of light

iTrader: (8)

I was on the stock ECU for years with a downpipe, stock cat, PFS catback, and intake. It worked fine and was a good improvement over stock. Don't forget that the stock ECU will activate fuel cut if the boost gets above about 12PSI.

pistonssuck

My next purchase is going to be a power fc. If so when I do get it is there a pre set for the mods that I have? Does it come like that if requested by the shop? Can I manualy put the preset in myself if I had a pre set diagram to look at? Would I be best off getting it dyno tuned? Personaly with the hp that I would be geting from the mods that I have wouldn't be worth the $ for the tune and the incovenience of commuting 3-4 hours. Or am I up ***** creek without a paddle?

cptpain

iTrader: (1)

I believe all pfcs being sold come with a base tune for intake exhaust and smic. But dont quote me on it.

As with getting any programmable ecu you need to tune asap so that it is tuned for your exact mods and your climate and altitude. There are a few rotary tuners out in your neck of the woods so gettin tuned should not be an issue, especially when you buy a pfc from them they should be able to offer a tuning session at little or no cost.
Some searching would do you good in that regard

Montego

iTrader: (1)

the stock ECU runs rich enough to support all bolt ons at 10 psi.

I had a CAI, PFS SMIC, MILD STREETPORT, DP, MP,CB. I maintained my boost to 10 psi MAX via a ported wastegate and a boost controller. Ran like that for years and WOT every chance I got.

j9fd3s

iTrader: (3)

there is a guy on here, arghx who has posted a bunch of info about how to make the PFC safer, and how it works in general.

its all simple stuff too