larger injectors that idle like stock??? - Boost Forum

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larger injectors that idle like stock???
Thursday, February 10, 2005 7:47 AM
hey guys whats up

im looking to see which injectors you guys think are good for low boost situation that will still idle like stock now im only looking to support up to 8psi out of the gm s/c

thing is right now im running 35lb ford brown top injectors @6-7psi and im still not fully happy with my idle even with them set at 35psi so im looking in to other options

what do you think is a good low imp injector to use on a 2.4that is larger but will still idle like stock i would imagine something around 30lbs would be good but im not sure maybe you people out there with a little more experience with injectors could help me out

also the injectors that i have tried are the HO injectors, didn't like how my engine reacted with them seemed like the engine was running rougher on them so i took them off, and with my stock ones i wasn't getting enough fuel because of my pumps psi limit(which will be replaced very soon too) and right now i have the 35lb'ers which stumble every now and then when i come to a stop or just sitting there idling but i can get more then enough fuel from them and car runs great when riding but the whole stumbling thing is beginning to wear on me

if anyone out there would like to trade injectors too i would be up for that, if they are looking larger injectors and have some slightly smaller ones to trade, my brown tops are like new

please let me know what you guys think i should do


thanks





Re: larger injectors that idle like stock???
Thursday, February 10, 2005 7:59 AM
any bigger injector will flood a little bit at idle therefore causing it to be a little rough......reason being is this.....factory 19lb per hour injectors are what the car is programmed for...so lets say the fuel map calls for 30% pulsewidth at 1000RPMs......well then you put in 30lb per hour injectors......30% of 30lbs is a hell of a lot more than 30% of 19lbs....so therfore you are getting more fuel dumped into the engine...so without changing the fuel map.....it will cause a rougher idle with bigger injectors



Goodbye Bobby, May God grant you the peace you never found in life.
“Here's my counter-offer to your counter-offer: go f**k yourself.”
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Re: larger injectors that idle like stock???
Thursday, February 10, 2005 9:00 AM
i have 42lb injectors with an safc2 and stock fpr and it idles just like stock it pulls 14-15 on the wideband
Re: larger injectors that idle like stock???
Thursday, February 10, 2005 9:08 AM
Crash wrote:

factory 19lb per hour injectors

2.4s are 24lb/hr, aren't they? That's what I've picked up reading this forum, anyway...



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Re: larger injectors that idle like stock???
Thursday, February 10, 2005 9:22 AM
Exactly what Crash said bro - I emailed you about the idle problem and decided to go with the S-AFC.

I know 1 or two people are running the Ford Brown Top / FMU / S-AFC combo and they're VERY happy. I just need to install my S-AFC - it will let you control the fuel maps and get a much better idle... you can also take care of high throttle and low throttle.

VERY much worth the investment.

-Chris-



-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Re: larger injectors that idle like stock???
Thursday, February 10, 2005 9:32 AM
Raptor wrote:

Crash wrote:

factory 19lb per hour injectors

2.4s are 24lb/hr, aren't they? That's what I've picked up reading this forum, anyway...


Yeah they are, the 2.2's are 19 lb/hr.

Crash wrote:

any bigger injector will flood a little bit at idle therefore causing it to be a little rough......reason being is this.....factory 19lb per hour injectors are what the car is programmed for...so lets say the fuel map calls for 30% pulsewidth at 1000RPMs......well then you put in 30lb per hour injectors......30% of 30lbs is a hell of a lot more than 30% of 19lbs....so therfore you are getting more fuel dumped into the engine...so without changing the fuel map.....it will cause a rougher idle with bigger injectors


You're thinking is a bit off, but the theory is the same. Neglecting fuel pressure, which changes with throttle position (and even more if you have a FMU), that works. But since the fuel pressure changes, so does the general size of the injectors. So...

Ford injectors are rated at 43 PSI, you have them at 35 PSI, so effectively at idle you are working with:
F2 = (35 * 30) / 43

24.4lb injectors at 43 PSI. Looks promising, but you have to remember that the 2.4L 24lb/hr injectors are rated at 55psi... so lets say they idle at 40 (I'm not sure what the idle fuel pressure is)
F2 = (40 * 24) / 55

17.4lb/hr.... All at 100% duty cycle. So if you want to figure out what your idle fuel pressure would have to be, to make your 30lb fuel injectors look like 17.4lb/hr fuel injectors (at whatever pulsewidth the ECU wants)...

17.4 = (X * 30) / 43

Solving for X

(17.4 * 43) / 30 = X

X = 25 PSI

Probably way too low for what you want, so the only way to get your 30lb injectors to idle like stock is to adjust the pulsewidth down, using an SAFC, E-Manage, whatever your heart desires that can change pulsewidths.






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Re: larger injectors that idle like stock???
Thursday, February 10, 2005 9:45 AM
well see the problem with the 35lbs are that they are so big that even with trimming them with a fpr they are still over 30lbs @ 35psi so the car cant handle them but i know the car can handle injectors at least around 28-29lbs so what i figure is get a injector thats around 30lbs and reduce idle pressure to around 35psi which will bring it down closer to stock injector size

i know for a fact that the 2.4 can handle 28.5lbs injectors because allot of people use the HO's and they idle fine

so the goal i figure is to find one smaller then the 35's but still larger then the 24 stock ones, the HO's would be awesome if they didn't crap out around 60psi

im not going for crazy psi of boost out of a turbo charger here im running the gm s/c so its say the same cfm so its not like i need 35lbs injectors @ say 80psi lol right now im using them up to 60psi and its still more fuel then what i need for my current setup im just running rich to be safe, i just need something that will support up to say 220-230whp which im sure 30lbs injectors with a fmu can handle, with a larger pump


i just need some idea of injectors




Re: larger injectors that idle like stock???
Thursday, February 10, 2005 9:50 AM
RC 320cc Injectors

http://www.carcustoms.net





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Re: larger injectors that idle like stock???
Thursday, February 10, 2005 9:53 AM
Either that or the 270cc ones....





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Re: larger injectors that idle like stock???
Thursday, February 10, 2005 10:00 AM
i personally was thinking of the 270cc RC ones. that way it is a little bigger then stock, but can handle the high pressure when need be.

Another thing i am looking into, is having RSM flash my computer/ get ride of the EGR code they say isnt a problem, but they arnt sure about running there s/c reflash on a car with a different power curve/ GM s/c.
But i will keep u updated on any info i find out for sure .




Re: larger injectors that idle like stock???
Thursday, February 10, 2005 10:26 AM
jake i was just gonna email them about the same thing last night lol but i forgot to when my girl called me up on the phone

damn girls they can be a distraction sometimes to what needs to get done lol





Re: larger injectors that idle like stock???
Thursday, February 10, 2005 10:28 AM
ya, i will probably give craig @ rsm a call today on my way to work. Price i think is around 350$ . I will let him know i have another guy interested in the same thing as me. I will keep in touch.





Re: larger injectors that idle like stock???
Thursday, February 10, 2005 10:32 AM
I don't understand why you want to change injectors when you can get a S-AFC for $200 USD and be able to control your ENTIRE fuel curve, including at idle?

-Chris-



-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Re: larger injectors that idle like stock???
Thursday, February 10, 2005 11:48 AM
Jake wrote:

ya, i will probably give craig @ rsm a call today on my way to work. Price i think is around 350$ . I will let him know i have another guy interested in the same thing as me. I will keep in touch.



cool sounds decent to me keep me updated

thanks




Re: larger injectors that idle like stock???
Thursday, February 10, 2005 12:29 PM
your preaching to the choir here...I have 83lb per hour injectors...I used to have a standalone too so it wasnlt a big issue but man that thing idled like a V8 with a big cam



Goodbye Bobby, May God grant you the peace you never found in life.
“Here's my counter-offer to your counter-offer: go f**k yourself.”
—Al Swearengen
Re: larger injectors that idle like stock???
Thursday, February 10, 2005 4:25 PM
anyone here running any ford 30lb redtop low imps????




Re: larger injectors that idle like stock???
Thursday, February 10, 2005 4:33 PM
The Red Top's are high imp bro...

-Chris-



-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Re: larger injectors that idle like stock???
Thursday, February 10, 2005 4:48 PM
really i thought that they didnt use high imp back in the 80's? there off a 1990 thunderbird supercoupe

i know they have new red tops that are high imp wasnt sure about the older ones




Re: larger injectors that idle like stock???
Thursday, February 10, 2005 5:01 PM
listening......


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Re: larger injectors that idle like stock???
Friday, February 11, 2005 7:16 AM
hmm, seems RSM is having some problems with custom OBD2 stuff. I will be the first to know when things get worked out. I hope they do. Guess we will have to wait and see. (cross's fingers).







Re: larger injectors that idle like stock???
Friday, February 11, 2005 9:17 AM
Jake-

Can you give me contact info for the person you are talking to at RSM? Maybe an email address or something? I need to find some information about unlocking the PCM, and they might know...






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Re: larger injectors that idle like stock???
Friday, February 11, 2005 10:25 AM
how about them red tops i was talking about anyone know if there high or low imp, there from a 90 firebird supercoupe??




Re: larger injectors that idle like stock???
Friday, February 11, 2005 10:54 AM
Red tops are high impedance, they used some high impedance injectors on some of the turbo birds.





4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!

Re: larger injectors that idle like stock???
Friday, February 11, 2005 4:23 PM
ehh does anyone know of any 30lb lowimp injectors?




Re: larger injectors that idle like stock???
Friday, February 11, 2005 4:30 PM
if anyone has any low imp ld9 24lb injectors that they wanna sell let me know....



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