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5.0 gurus check this out..

1K views 77 replies 12 participants last post by  blk87coupe 
24's are too small for one. redegee the cam. His fuel with that small of inj should be around fifty give or take 10lbs. More so give than anything. Pull the plugs and I bet thay are clean and white as can be. also might want a taller tire if he not using a 28
 
Those 24# injectors are not too small. The cam should be checked. The fuel pressure would not need to be that high. In doing so, the computer will turn down the injector pulse rate, thus leaning it out even worse. A tune will do far better, as it will work with the stock fuel pressure, and work very well with driveability. High fuel pressure will not help driveability, as it will be dumping fuel at idle and low rpm. The plugs very well could look white, as the O2 sensors have no clue what's happening other than it just isn't right. 28" tire would be the tire for those gears.

So, you were close. It certainly was on par with how things were done for 5.0's back in the day before folks really caught on to what they were doing.
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stick it on a dyno or with a wide band and I bet its way lean. Please dont send him for a "chip tune" . They do not work with pre obd-II fords. I have built countless cars that prove that.
 
I'm sure you have.

That is why you are saying 24 lb. injectors are too small for what is basically a 300-320 rwhp setup and that he should run a 28" tire.

Everyone knows you need 28" tires to run 12s!
ow much horsepower will a 24lb inj support? How much power is 300-320 minus drive train loss ? And that gear is too much for that.
 
If you're talking about a chip that someone burns without running it on the car, just by guessing, then yes you are correct.

If you mean something along the lines of an SCT that gets burned while tuning, then you are can't really be serious.

I'll contend that the plugs probably look white, but it's going to be more along the lines of the cylinder filling at the wrong time, burning wierd, throwing the o2 sensors off, and the computer is trying to catch up.

I'm well aware of what works on EEC-IV computers. It is my passion. I am rather fond of Fox Bodies regardless of all there issues.
I am dead serious. I am a fox nut and have had hundreds. I have tried having chips burned on dyno's for persistant customers and its never optimum. You can make these cars run and run better with up to 42lb inj and large cams with big heads by simple tuning and tweaking with out the chip. I would suggest a PMS or some other higher level tuning for anyone wanting to modify pids and tables. A chip is never something I would recomend nor do the shops try to push those.
 
Naturally a different computer that supports more tuning ability is optimum. This guy does not need that yet. He has a basic combo, that has been done the same for a very long time.

Hell, a Tweecer will do what he wants, if he can find someone willing to work with it.

I know how well it can run if he goes bigger. He's not. His friend is questioning this setup. Stick to what's pertinent. Let's keep him in the basics until he finds out what's up. Then he'll want to go faster, and I'm betting he'll post up a "What's next?" thread.


Al, I figured the cam pulls hard to 6250. My reference was for folks with the basics running in the 1/4.
I completely agree. thats why in my original post I said he should set the cam back to straight up, set his pressure around fifty, and try a taller tire. Thats pretty basic for his prob.
 
You asked how much power 24s can support. I told you. That's the point.

The way this works is, after I respond to your questions, you then respond and add something further to the discussion. I know it is complicated but please try to keep up.

Go ahead and explain to us why he needs a bigger injector.
24's will only support 375. that is all they are rated for and as a general rule of thumb thats a median rating. Now I know this is hard to grasp but every scenario has variables and sometimes there are freaks and exceptions. you have pointed out one exception.
 
The only thing I disagree with here is the fuel pressure. You said it yourself that it's a bandaid. Fix it right, with a tune. I would rather have the driveability, and longevity, personally.

Do you agree the injector pulse rate will be reduced due to dumping too much fuel at low rpm by simply adding fuel pressure?
Again. I said the fuel pressure is more so a test. Like I said. i think it needs 30's. He could do nothing more that swap inj and meter or sampling tube and cure all. I think he has multiple probs and lean is one. Yes the high fuel pressure will affect the low rpm driveability and fuel maps but it would point him in the right direction. My original post states that. I do not agree with the one thing of a "chip tune", I have had every local shop burn one on a dyno and never had one work right.
 
You can support 400 rwhp with 24s every day, all day long. It isn't a freak exception or anything remotely resembling that. If you don't realize that then you don't understand the nature of injectors, it really is as simple as that.
Your crazy. Even with a complete fuel system and all supporting good hardware that is stupid and a death wish.
 
I guess all the 93 Cobra owners who put an S-trim kit on their cars with 24 lb. injectors and made 400 rwhp are crazy, stupid and have a death wish.

Dude, get real, you don't know what you are talking about on this subject. Stop embarrassing yourself.
Never saw a stock 93 cobra with a "s" trim make 400 with 24's. Saw lots of them with A and B trims making
over three but never what you are claiming. Can you produce some or you just talking out of your ass like normal. And since a S trim was the upgrade they came with upgraded FMU with a 6BTM and recommended inj and maf swap
 
Check the cam. Disregard the back and forth, as it's not important at this point in your venture.

The rest of your setup will live a long life on the stock computer parameters, provided the MAF is the one for those injectors.

I might suggest getting ready for new o2 sensors, and clearing out the codes that are probably built up in the memory. Run it for a while, and then check codes for shits and giggles later.
Correcting the cam is not gonna be the cure all. It agreablly is the biggest concern and prob more than likely but he needs to address the fuel problem. His O2's if they are bad had to have been burnt or fouled for some reason or the other. And when a computer does not see a 02 signal it goes into a preset function and will run with out them. Hell I would bet that half the foxes out there are or have been running with out a 02 siganal for one reason or the other.
 
Agreed, but that 80% is a safety factor - we regularly run them at 95%+ A very small tweak on the pressure will bring that down pretty far.
Im really not trying to get into a pissing contest with anyone. but If this man was a customer of mine I would tell him to set the cam back to straight up or even retard it 2 degrees, add fuel one way or another and tray a taller tire or lower numerically gear. obviously tires first
 
With the FMU that is included in the S-trim kit the fuel pressure rises at an 8:1 rate. You already know all this but I will say it anyway since our other reader appears to function on the third grade level.... at 10 psi of boost you have 80 psi of fuel pressure. Since injectors are generally rated at 43.5 psi of pressure (or somewhere close to that), it isn't rocket science to conclude that you will make more power at 80 psi.

Or maybe it is rocket science, I don't know. :banana:
So when I say he needs to raise his fuel pressure its stupid but when a blown app boost fuel pressure its ok. And I merely used the website as a pop up pic book for you. And the diaphrams in the FMU are also diff come in different calibrations. But we are not talking about a blown app using a fmu. We are speaking of a should be 300+ n/a app. Therefore if you base the flywheel power off that and use the pop up book page for calc. You come up with a 24being to small and in need of 30's.
 
the injectors are actually brand new, as well as the fuel rails and harness.. my buddy thought that was the issue initially. how can we check to see what the cam is degreed at? any quick and easy way? id love to help him figure out a fix, he's been messing with this thing for way too long. and it makes me sick to think this car with afr heads, intake, cam, blah blah is running this slow. LOL.
Pull the timing cover. And or ask if he used a degreable timing chain or standard set. Or if he degreed the cam with a wheel when installed. Doesn't matter if the stuff is new he needs to check the plugs or stick it on a wide band and see where its at.
 
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