Drivarotor

I read somewhere that if you remap your ecu to 80% injector duty cycle you will gain considerable hp (20-50). Has anyone heard of this? If so, what other mods will you need to make to realize those gains (steps left out). Who remaps 2nd Gen S-5 ecu's?, or can it be done with a software package and a serial cable? Also, does any aftermarket outfit make an intake tube and filter setup (other than HKS?) that mates to the MAFS? Trust me when I say, I have a lot more questions and a VERY limited budget for my 3rd 2nd Gen.

rx7b13

i never heard of anyone gaining 20-50 hp from remaping the factory ecu. i might have been but like i said "I" have never heard of anyone gaing that much.

snowball

more fuel will be useless without more air.
do a search for cold air intake and read the FAQ

Black91n/a

I've read in several places here that it can't be done (not that it hasn't been tried). You need to get a standalone or a piggyback computer to tune the car.

Drivarotor

thanks. For an 89 n/a GTU, what would be a recommended piggyback and/or standalone ecu, and where could I find one? Who makes an aftermarket cold air intake for my FC? (other than HKS, because I dont consider theirs to be a TRUE cold air intake)

snowball

ECU's would be
Megasquirt and spark
Microtech
Haltech

Valkyrie

You realize that any of those standalone ECUs will cost more than your car, right? (except for the Megasquirt...) Not to mention the wiring cost, the installation or the cost to tune them, if you don't happen to own an dyno and know how to set an ECU up...

Also, putting a high-flow air intake on your car isn't what people are talking about... when they say more more fuel needs more power, they mean A LOT more air... as in, a turbo, or supercharger, or nitrous. At the very least, you'd need to port your engine...

Don't expect to gain more than 15 HP or so by computer tuning your car...

fcdrifter13

A guy on here makes the MS plug into the stock wiring harness for about $400 I beileve If thats more than the car then damn

Valkyrie

Pay attention :p

I said besides the Megasquirt...

And for the record, a $400 megasquirt would as much as my 89 GTU...

iceblue

MSnS PnP is $500 pre assembled. FYI I bought my Haltech E6K for 750 with harness predone. They are easly found for 500 to 900 dollors.

The factory ECU does not have a fuel map to remap anyways so this remaping is false no such thing to do. You can piggy back or chip such as Rtek. The NA runs so stinkin rich you want to use a SAFC type product and -fuel.

mwatson184

What are you guys talking about more fuel for. The stock ECU comes programmed rich in the top end. If you pull out fuel (less fuel people) you will gain power. There are significant power gains (significant for an N/A) to be had doing this. Most do it with an SAFC.

-Marques

Drivarotor

ok then people. here is the million dollar question, what would you recommend to be the most streetable n/a setup for a 1989 California emissions FC GTU? Given a budget of $1500, that includes wheels and tires (and I already blew $300 on the wheels) and most of the technical and mechanical work will be performed by myself.

Drivarotor

also, how reliable is the MS&S ecu?

iceblue

MSnS PnP all the way! muythaibxr has already compleated base maps for both S4 and S5 NA motors and he and tofubal have been building them to sell as a unit. You get to ditch the AFM and presure sensor, what more can you ask for then that.

Take the other 500 and buy a wide band AFR gauge.

get some wheels.

slpin

iTrader: (9)

you heard wrong
you should be leaning it out at the top end to gain any more power from your car

NZConvertible

Don't take this as a flame, but this statement shows you have a lot of learning to do on EFI before you can start modifying it.

The phrase "remap your ECU to 80% injector duty cycle" doesn't make any sense at all. Injector duty cycle is not a fixed value; it is constantly varying between 3-4% at idle and a max of 60-100% depending on mods. It is the percentage of time the injectors are open (the pulsewidth) during one engine cycle. Because the pulsewidth varies with engine load and the engine cycle duration decreases as revs increase, you can see that thinking of injector duty cycle as a fixed value is just nonsense.

The ECU decides on the necessary injector pulsewidth by looking at a table pulsewidth vs. load and rpm. If you can imagine a spreadsheet with rpm down the side, load across the top and pulsewidth in the cells then you'll have an understanding of the basics of EFI.

Factory mixtures are conservatively rich because rich mixtures keep the combustion temps down and hence suppress detonation. That's how manufactureres protect their engines. The downside is that less heat means less power. Obviously you don't want to be adding more fuel if you want more power; you want to be removing some. You can gain a bit of power by using a piggyback fuel controller to lean these mixtures out a bit while still providing enough protection against detonation. A 20-50hp gain is completely unrealistic though; you can expect maybe 5-10hp tops. There's more potential with for gains NA engines as they can run leaner full-power mixtures than turbos.

nexpo8

i made my custon CAI from a prelude pipe. (i got a lil help from Ddubs page) just look for my thread u will see picks of it if ur still interested on a CAI. it's VERY VERY cheap not any more than $40

sar

iTrader: (1)

While a cold air intake pipe will help an engine breath a little bit easier it will not significantly change the mixture and has little significance in this thread.

An s-afc2 costs ~$200 on ebay and is possible to tune yourself - you can save gas on highway and have about 10hp more top end due to the leaner mixture - this lean mixture can affect your catalytic converter life though.

arghx

iTrader: (3)

why are we even talking about ECU stuff for a stock N/A ? The first thing you should do besides a tuneup is ditch the extremely restrictive stock exhaust. I'd get a Racing Beat header or cat replacement pipe, Bonez high flow cat (since you've got emissions testing), and a Corksport or Racing Beat catback depending on your preference. This will kill your planned budget right there.

Then you can eventually go and buy an SAFC off ebay and lean it out a little bit. If you do some porting though you'll find that you will actually need to richen it up significantly.

MaxDuo

He said it has to pass CA emissions. He'll have enough trouble with stock exhaust

iceblue

If he kept the stock port timing and increased the port runner it would prolly help allot and come into spec but be far from needing fuel. If you start advance and closing the port timings on the 6pt motor you affect the VE. The 6pt intake manifold was designed for 4 harmonic bounces, when you change the port timing you destroy all the work Mazda did and will prolly lose in the end. When you change the timing the resonance of the plenum is thrown out of whack and you lose the pressure differential Mazda designed thus less air in and more air pushed back into the intake.

I have been trying to draw up my own port design for the 6pt motor NA only. See how it does soon enough. Still more research needed and a donor car.

Drivarotor

ok, so lets say we can add a bit more to the budget, like $500 or so, will a lightened flywheel make any difference in accelleration? Take into account I have already ordered my RB header, Bonz cat, and Rotary Performance cat back system. Secondly, I saw someone say that port matching will smooth things out considerably. If I do that myself, what tools are going to be needed? (I have a compressor, dremel, grinder and d/a sander).