Ford Mustang Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
7,462 Posts
Discussion Starter #1
I am thinking of getting a set of 42 lb injectors. Currently I have 24 lbers. I just bought a 9lb powerdyne. I have not gotten it yet.
I am preparing for it.
If I run 42 lb injectors will I need to run a FMU or can I ditch it?
 

·
US Navy Active Duty
Joined
·
652 Posts
You can ditch the fmu but will probably want to have your car tuned. I just ditched my fmu today but really wish I had gone with 42# injectors like you are doing.
 

·
Registered
Joined
·
7,462 Posts
Discussion Starter #3
What size do you have?
 

·
US Navy Active Duty
Joined
·
652 Posts

·
Registered
Joined
·
96 Posts
When I first installed my 42lbers and ran without an FMU or chip, I had to raise the fuel pressure to about 50 lbs at idle to keep it from leaning out at higher rpms. It makes it run rich at idle, so be prepared for poor idle and fouled plugs.

Also, I hope you also installed a mass air meter cal'd for 42lbs or its gonna run really rich.
 

·
US Navy Active Duty
Joined
·
652 Posts
QwkPony said:
When I first installed my 42lbers and ran without an FMU or chip, I had to raise the fuel pressure to about 50 lbs at idle to keep it from leaning out at higher rpms. It makes it run rich at idle, so be prepared for poor idle and fouled plugs.

Also, I hope you also installed a mass air meter cal'd for 42lbs or its gonna run really rich.
Just curious, what do run your fuel pressure at now? I have to run about 45-50psi with vaccum off to keep from going lean up high also but I'm running the 36# injectors.
 

·
Registered
Joined
·
1,145 Posts
If you go with the 42's and a matching MAF, you can and should ditch the FMU. That combo will support a bit over 500rwhp. Raising the fuel pressure beyond the stock pressure will make your car run like crud. The best MAF on the market is the Pro-M Univer. Of course, you should follow up with a tune right after the work.
Have fun!
 

·
Registered
Joined
·
7,462 Posts
Discussion Starter #8
I am getting reayd to buy the 42lbers and matching Pro M.
Currently I have a C&L 76 with 24lbers. I also have a FMU set up 24lbers. I have not install the powerdyne yet.
Why would fuel press with the 42's have to be set so high?
I thought bigger injectors required lower pressure and smaller injectors required higher press?
 

·
Registered
Joined
·
1,145 Posts
He should not have had to raise his FP so high with the 42's. Chances are, his MAF wasnt calibrated correctly, and his meter was pegging out mid-rpm - causing it to go lean. Very common problem. Alot of people compensate for that problem by cranking up the FMu but thats a crappy way to fix the problem.
 

·
Registered
Joined
·
7,462 Posts
Discussion Starter #10
So if i put the 42lbers with matching meter, will i have any idle or drivability issues?
 

·
Registered
Joined
·
1,145 Posts
You may still have idle problems - I did until I got the Univer MAF. Other than idle, your car will run awesome - BUT, make sure you get a chip or some kind of retarding system. The stock computer may be too aggressive!
 

·
Registered
Joined
·
7,462 Posts
Discussion Starter #12
I plan on running a BTM.
 

·
Registered
Joined
·
39 Posts
I have an S trim about 8lbs now 80mm C&L MAF 36lb injecters. I have a Nordscog Rich lean gauge and with 32 lbs fuel press. w/vac disconected It does not run lean. I had an idle surge problem that I had played with fuel pressure up and down from 45 to 30 with no effect on surge. I then played with relocating the MAF so it was futher away from the blower inlet and inside the fender well and more of a straight pipe before the MAF. This cured my high idle and surge. Also I was told by a very reputable guy at CCM that with big inject 36-42 without FMU and a suffucient pump high pressure would not be needed.
 

·
Registered
Joined
·
245 Posts
My 30s were good to 440RWHP with 8lbs of IC boost, and 490 with 10LBS of IC boost w/FMU. I think 36s would do for 440 of nonIC boost and no FMU. 42s will be more than enough.
 

·
Registered
Joined
·
211 Posts
Not knocking the powerdyne or anything, but I bet you'll be safe with 36lb inj without an FMU with the PD. If you had a vortech/novi/procharger, then I'd say step up to the 42lb. If you buy the 42's, and have some problems, yell at me and we can slap on my old 36lb/77mm pro m meter (and hook up the wide ban) and see how they behave. Hell, I even have a super FMU laying around somewhere here.......
 

·
Registered
Joined
·
7,462 Posts
Discussion Starter #16
Well I have already bought the 42lbers. They are on their way here as we speak.
I will def. keep you in kind if I have any problems. We need to meet up some time.
I need to meet some local stang guys.
 

·
Registered
Joined
·
705 Posts
Fuel Pressure?

I just installedmy 42's with 80mm mass air and i have a V2 SQ with the 6-8psi just wondering where i should start for fp settings. I thought about setting it at like 30 then using a 4:1 fmu disc
Is that a bad idea or you guys have a better idea?
:confused:
 

·
Registered
Joined
·
102 Posts
BBBAD 5.O said:
Not knocking the powerdyne or anything, but I bet you'll be safe with 36lb inj without an FMU with the PD. If you had a vortech/novi/procharger, then I'd say step up to the 42lb. If you buy the 42's, and have some problems, yell at me and we can slap on my old 36lb/77mm pro m meter (and hook up the wide ban) and see how they behave. Hell, I even have a super FMU laying around somewhere here.......
Darn, must be something wrong with my setup!!! My 42's are going 100% duty cycle at 5100rpms on my Powerdyne with 55psi fuel pressure, now where did I stash those 36's??

Jim
 
1 - 18 of 18 Posts
Top