problems with miata
 

so i took my miata to get it tuned it pushed good power but the safc is maxed out to 50% and its runing lean in boost do you guys think i could be a bad safc? or do you think my ecu is reading boost? in boost its runing 13:1 ratio and i am runing 8 psi in boost and the damn thing still runs lean and i have the lite purple 265 injectors! the guy that tuned it is just is stumped as me so any help would be great!!!!!

what happens to the fuel after 5K?

it goes up like 4 psi

no, sorry the AFR.

uhmmm. maybe you are running out of fuel? lol. The S-AFC isnt going to make the injectors and pump do more than they're capable of doing. Upgrade the fuel pump and put an RRFPR on there. problem solved. Check the fuel filter too.

13:1 in boost and you want it under 12 slos13- i have a 255 walbro and its a full tank of 91

so no matter what, once you're in boost you have a 13:1 AFR, it doesn't change at 5.5K or so?

You're really not giving us much, if anything, to work with.
What turbo? What was your dyno result? Where's the plot? You don't even tell us what year or motor.

Also slow down when you're typing and proof read. If I have to decipher quasi-english to english, I ain't gonna help ya nun.

1.6 turbo is a 16g, 1990 8;5;1 comp wiseco pistons, mazdaspeed miata injectors 256cc,255 walbro

is a 250cc injector enough to support 8psi worth of power at stock pressure?

I dont have a calculator on hand but it seems to me as if you should be running either more pressure or a bigger injector.

i have one of those cheap afpr off ebay, do you guys think i need bigger injectors?

I would get a BEGi FMU, and probably throw away the SAFC and definately throw away ebay crap.

Why would you put cheap ass ebay chineese crap in charge of delivering fuel?

so get a begi and a safc 2?

cutting corners is sometimes allowable, but never on fuel delivery. get the real stuff for that. Also make sure your ebay POS isnt hooked up backwards

Hell no. No way should you spend $400 between 2 fuel piggies.

Just get a BEGi FMU and be done.

If you want to spend $400 get a vortec and pick up a used emanage blue.

Or a new AEM piggy.

Or build a MegaSquirt.

Or spend a little more and get an MSPNP

so what tunes the car then? just the begi? and my injectors are ok? should i make and dual feed rail? could i get a e-manged instead?

on your year miata.....

under 4-5k rpm (not sure what the cutoff point is) the stock ecu operates in a mode where it reads from the oxygen sensor and automatically adjusts inector pulse to keep the engine running stoich (14.7). Above 4-5k rpm (again i forget what the cut off is), the oxygen sensor and ecu stop working together, and the ecu feeds fuel according to a preset fuel map.

Therefore a real rising rate fuel pressure regulator like the begi or vortech, will only give you noticeable results after the motor hits the rpm at which the ecu goes into the preset map mode because at that time, the injector pulse width does not change according to what the o2 sensor and ecu determine should yield stoich....so the rrfpr simply clamps off the return line to your fuel tank, the pressure in your fuel rail increases, injector pulse stays a preset lenght, so the overall amount of fuel going into your motor increases.


to answere your main question...yes, without a piggy back of different ecu, the begi or vortech is what tunes your car (but only after the engine hits a certain rpm). to tune the air/fuel ratio below that magic rpm, you need an oxygen sensor clamp which allows the stock ecu to ignore the output coming from the o2 sensor and you to up the fuel pressure under the magic rpm with your begi or vortech.

if it doesn't make much sense....read up on your miata fuel system and it's return system, braineacks' faq, and corky's book maximum boost, and talk to olderguy about his oxygen sensor clamp.

you're on the right track, just need some details hammered out.

p.s. most of those ebay fpr's only up fuel pressure on a 1:1 ratio (1 pound of boost coming out the turbo only increases pressure at the rail by 1 pound)
the begie and vortechs rise fuel at a 6:1 - 12:1 ratio. that's what you're gonna need to get yourself running not lean.

Anthony

The above quote was the only factual information from that entire post.

The rest is so wrong I'm not even going to start with it, and should be ignored if not deleated.

so all your saying is i need to take the safc out and put on the vortech or begi and a 02 clamp and i wont have problems when i get it tuned

if you get a static ratio FMU, there's really not much to "tune".

If you keep the SAFC2, you'll have some level of tuneability by modifying the AFM output voltage that the ECU sees. Now, the FMU works off of pressure while the SAFC2 is reading off of mass so it's not an ideal solution but it'll probably work good enough.

I imagine you could hook up a MAP sensor to the S-AFC and tune by pressure but thats another bag of worms

NO. what i said in my previous post was not wrong. to sum it up, a rrfpr is pointless to adjust to a/f ratio when the miata is in closed loop, because the ecu will just try to maintain stoich even though the rrfpr is upping the pressure as you build boost at low rpms.

once the computer goes into open loop mode(at higher rpms), and runs off a fuel map, the increased fuel pressure due to the boost acting on the rrfpr can be used to adjust a/f ratio becuase the computer is not trying to maintain stoich, but is fueling based off of a preset map.

so to tune your a/f ratio with an rrfpr at lower rpms in the first gen miata, you need to have an oxygen sensor clamp!

Talk to olderguy and braineack. I might not be the best at explaining it, but without a different ecu or a piggyback, an rrfpr won't do much for your a/f ratio at lower rpms (while the ecu is in closed loop mode)

p.s. the begi and the vortech are both 'tuneable' the vortech uses different discs to adjust how much fuel pressure increases per pound of boost, while the begi's pressure rise to boost ratio can be adjusted infinitely with the built in adjustment screws on the unit.

Anthony

You are still wrong. And repeating yourself, or just being beligerent, doesn't make you right.

You are an idiot the afm is tuned for the rate and the fpr helps make the injectors act bigger but i did see some nice gains by leaning mine out abit up top and richening th emidrange with my safc, and 105 psi of FP. The adjustability of the safc does not do alot for driveability without a TPS but it still helps if the driveability is decent and you want more power. 90 miata you can have my 12-1 rrfpr for 55$ shipped if you like lemme know. your 265's wont pull alot of fuel on stock fuel pressure but i already told you that. 265*.9/10.5/.5*4= 182 bhp add another say 40-50 psi of Fuel pressure and you have 364 cc/min at 85 psi *.9/10.5/.5*4= 250 bhp are you folowing me now? also please remember a general rule of 15% drivetrain loss for most miatas.

not if you tell the computer you aren't adding fuel. And even not it will still dump in the fuel and the ECU has to deal with it, but that's why you hear about hesistation between vacuum and boost. But never that a FMU won't do anything.

who? me?

No scot of course you :crx::dancegay::inout:

you speak in riddles.....and smileys.

idiot may be strong. arrogant perhaps. a trait we share.

I speak from experience--not from what I've read. And I've had like every possible type of fuel management on my car.

Ben

well fighting over whos right isnt going to work for me to well come on guys lol so all i need is a vortech and a flyin' miata o2 clamp? and take out the safc

vortec or preferrably BEGi FMU. i didn't need an o2 clamp with the BEGi. if you are going to get one, get the less expensive OLDERGUY o2 clamp. Details the classifieds, in a sticky.

nah man all you need is a rrfpr realy like the one i offered you the 12-1 is abit agressive but it will do the job just fine. the safc is just fine by all means keep it, but more fuel pressure will help you in boost. I ha dno problem at 12psi with my 1.8's, walboro 255hp, obx rrfpr, and a safc2. The only thing you dont have that i did is the rrfpr. lemme know man ;)

pull the safc and set it on fire.

do the math, figure out how much fuel you need, and do it the easy proven way.

I agree he needs the extra fuel pressure but the safc can lean out the top end problem you and many others where strugling with on stock ecu and like i said i noticed a good difference in midrange when used with the 1.8's. It is not as good or robust as MS but it still does the job scot. don't hate on him or confuse him he is having enough of a rough time with this as it is.

i dont think i was being harsh....

seems kinda anti safc to me.:crx::vash:

so, I could have said like Richard is fat and smelly don't listen to him.

and it's not that I'm anti SAFC, it' sjsut that I know the fmu/fp/o2 clamp combo works, and works well.

I dunno much about the safc, so if it can lean out the top-end, then great. but as is, he still needs fuel pressure holmes.

Ben
You are still wrong. And repeating yourself, or just being beligerent, doesn't make you right.

Whoa there fella :eek4:. lol i wasn't trying to up the tone at all!

Braineack
not if you tell the computer you aren't adding fuel. And even not it will still dump in the fuel and the ECU has to deal with it, but that's why you hear about hesistation between vacuum and boost. But never that a FMU won't do anything.

I'm not saying the FMU won't do anything in closed loop. The FMU is a means to mechanically raise fuel pressure in our efi return fuel system. What I was trying to say was that in closed loop mode, the ecu tries to compensate for the mechanical clamping of the return line that ups the fuel pressure. So braineack, like you said, a solution is to 'tell the computer you aren't adding fuel' when you're in closed loop. That's why i said about the olderguy 02 clamp.

I never said he didn't need the rrfpr.
He bought the ebay stuff to stabilize his idle fuel pressure wich is all well and good if he can get it to work as advertised i never could. But i think he either forgot or got confused on his way to a rrfpr. Don't get a sandy gina on my now. You would smell a month away from your yearly bath as well. The creek is finally gettting warm enough for that stuff in KY gees. :gay:

im laughing over here. i threw in my two cents and you're freakin out on me, I barely read through the posts.


and please refer to it as a fmu, i hate seeing acronym rrfpr


and you better watch who you mess with, I can remove your avatar, then you'll feel silly paying $3.50 for nothing :gay:

nah i am just extremely bored. Car is running well and i have nothing to complain about. Making myself think you have it in for me makes the posting more fun. Still 90 miata deserves the full attention of the posters, after his oil burning troubles etc, i realy hope he gets his stuff together soon :D he seems to get abit confused sometimes but i believe he has the right idea now hopefully he just needs to figure out how he is to go about it.