If I put the fmu on w/ a 19# disc and I'm runnin 24# injectors will it mess something up or just not run to its full potential? How will I know if the wrong disc is in? Also if I get an adjustable fmu how do I know what it is set for?
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If I put the fmu on w/ a 19# disc and I'm runnin 24# injectors will it mess something up or just not run to its full potential? How will I know if the wrong disc is in? Also if I get an adjustable fmu how do I know what it is set for?
can I use a vortech recalibration kit in a paxton fmu?
It'll just run huge fat, is all. Why don't you use an 8:1 disc for 24s? The Vortech ones and the Pax ones are interchangeable.
F=MA
Adjuctable FMU still has Disc that you change to get to the best A/F ratio for your car.
I have a paxton fmu and don't know what disc is in it. Thas why I was wondering about how it will run cuz if it has 19# disc I have 24# inj in it right now and don't wanna mess it up. So even if I get an adjustable on I'd have to buy more discs?
Super FMU comes with all the disc and has other settings you can change to get a better tune. Go to Vortech web site and it has listed all the disc sizes and what Lb. they are for. You can even search this site it has been listed many times.
Ok, I'm running a red (10:1?) paxton FMU with my 24lb injectors... Is this the wrong one? Should I be running 8:1?
My kit was originally off a '93 cobra that had 24lb injectors, so I asumed I had the correct fmu...
Sorry to hijack the thread.
when I looked online it showed a different disc for the 24# cobra injectors and i guess ho 24# injectors. Whats up w/ that??
The guide to sizing FMUs on Vortech's sitte and others is a rough guide only and pretty safe. Your needs will be determined by your engine and the volume your fuel system can sustain under high pressure.
8 or 10 to 1 could be correct for 24s. You need to do a plug chop/dyno run on the safer 10 and see what's up. The 93 Cobra kit is on a richer tune not because of the injectors but because of the heads, cam and intake, plus the computer settings. The motor has higher specific output than the regular 5.0 on E7s.
F=MA
so if I have a completely redone block w/ a holley systemaxII kit and anderson pms what size disc should I go w/ ??
If you have the Anderson, you should junk the FMU, put 42 pound/hr injectors in and tune it in properly.
F=MA
Good info, thanks. I guess I'm better off with the safer 10:1, better safe than sorry. One of these years I'll get bigger injectors and a tweecer... Maybe. :cool:
how bad will those make the gas mileage?? My car is already pretty bad on gas but I'd like to be able to cruise it on the streets still.
Tuned correctly, the loss should be minimal. I find that, however, anything above 36s starts to have a detrimental effect on mileage, as it gets progressively more difficult to dial in idle and low speed fueling. You might lose a mpg or two going from 36s to 42s, even tuned in right, it's hard to say, as so many other factors affect mileage.
Honestly, if a stock displacement EFI 302 is bad on gas, something's wrong, either with your foot or the engine. These cars are really quite sippy for a 5.0 litre engine, especially on the highway. I have busted 30 mpg frequently on my 5.0, with 3.55s, on the freeway, and typically sit around the 18-20 around town. Now, that's on an Imperial gallon, which is slightly larger than your US gallon but, you can do the conversion if you want.
F=MA
so what you think the 36's would be better?
Better in what way? More mileage, more power? You need what injector you need. I think 42s are "better" because you're intending running forced induction on a full HCI package. The explosion from too little injector is going to be ugly.
F=MA
I use 42lb injectors and with the PMS and a Wideband for tuning I would get 20 mixed and 24 highway on trips. I would get 16mpg drag racing all day at Fun Ford and drive the car back and forth to the track. I never seen a drop in mileage from 3.08 to 3.73 either but then I no longer had to leave 5th to show a brisk acceleration on the freeway.
what is wideband? I keep hearing of the wideband o2 sensors, is that what it is?
A standard narrow band O2 sensor like the one in your regular car can only read in a very narrow range around stoich (~14:1) air/fuel. Since, ideally you want to tune for 12.5:1 or so for performance and safety, you need an O2 sensor that can accurately detect O2 in that range...hence, wide band.
You know, people always say that the only silly question is one that's unasked but, really, if you've been fiddling around with hot rodding EFI cars without the basic knowledge set, like what a wideband is, what FMU disc to use, etc., it's frankly amazing that you haven't blown the thing up yet. That's sure what happened when I started doing this decades ago and forged ahead with nothing but faith and ignorance to guide me. My wake is littered with broken parts and hard lessons.
F=MA
actually I'm asking before I put the stuff on so I don't blow it up thank you
everyone learned from someone or something right? I just prefer to ask people who are knowledgeable ahead of time as to find out the hard way. I appreciate your help very much and prefer asking you all because I always get 3 or 4 different answers or just get confused when I just do a search on google. again thank you all for the help
what wideband do ya'll recommend? Bosch?
If I recall correctly, you've already done a fair bit of hot rodding on your car already, which is what I'm getting at; it's not like you're starting with a bone stock 87-93 Fox.Quote:
Originally Posted by shadowgames81
If I could do it all over again, I'd learn to touch *nothing* before I learned how to touch it. Sadly, even if I'd wanted to do it that way back then, we didn't have the miracle of the internet to instantly place information in front of us. So, we just had to muddle through and, "pay up, sucka" when we blew things up. Good memories, though...:happy:
I'd recommend you buy Bosch, or Nippon Denso wide bands, as they are both in OEM use and have to meet that standard. A bit more money initially but, any instrument is only as accurate as the materials and design used so, no off-brand or second string crap cuts it here.
F=MA
no I actualy paid for people to do the work for me up until recently when I got more into it and wanted to do it myself and learn more. I think I will go w/ the 42's and the boschs then. Thank you all for the help. I'm sure I'll be back soon asking more questions.
People do that!? :D
Good for you for taking on the challenge. You'll be alot more proud of the finished product, plus more sure of what it'll really do, this way.
F=MA
This is the Wideband that I have used for the past 3 years. You can use a Laptop, PDA or a Dash Gauge. Excellent Unit
http://www.zeitronix.com/
So those widebands and the pms oughtta do it huh? Now when I put the stuff on should I take it and dyno tune it or try to have them put the stuff on and then tune it
Depends on your dyno operator. If they are intimately familiar with the PMS then they could guide you. If they aren't, find one that is. You can probably dial in the drive it down there settings pretty easily just by following the instructions. If it's anything like previous versions of the Interceptor II on which it's based, it's pretty user friendly.
F=MA
Sounds good thanks
Will it be ok to run the pms and sn2000 w/ 24# inj till I can afford to get the widebands and 42# inj? If I can should I just leave the fmu off?
I don't think the PMS has enough range to draw the 24s out in pulse width enough to support that. 24s will require an FMU. If you're at the standard 5 pound level with the SN, 10:1 should be nice and safe for an FMU disc.
Easiest is slap the 24s/calibrated MAF and the FMU on the engine and run it on the stock engine management, until you get the PMS and the 42s/matching MAF, then tune that all together.
F=MA
I would use the FMU and if you get the PMS before the injectors use it to bring down the fuel at WOT.
I already do have the PMS thats why I was wondering. So once I get that on and the fmu and all do I need a tune or wait till I get the 42's? I don't really want to pay two times or more if I don't have to cuz I don't have a ton of money.
You will be rich at WOT just because the nature of a FMU. Since what I was reading last week you still don't have the correct disc for the FMU? If not you can use the PMS to bring the fuel down at MId and WOT.
Yeah I'm not sure if the disc is right or not the s/c came off a cobra so I was thinking it would have the 24# disc but not sure. Also does the series of the pms matter? Like I think its the series 1 or 2 and didn't know if that would change anything as far as settings and widebands etc.. I really appreciate ya'lls help. No one around where I'm at that I've asked can help me w/ most of these questions.
If it came off a Cobra it will have the disc for 24lb injectors that is correct. PMS 1-2-3 are about the same just some added features every few years. You will feel the car bog big time if it is rich at WOT because that FMU will climb to about 70psi fuel pressure and just wreck a fuel map. The FMU is not accurate to say the least so when you adjust the injector pulse it can be risky.