4.9l injectors?
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4.9l injectors?
hi i got a 93 4x4 f150 4.9l 5spd 127,000 miles on it and i got the inake off and before ij put it back on i want to maybe change the injectors. right now i believe other people are saying they are 19# but can a put injectors from a 5.0l in it. and will that give me any more power than i got now or will it not make a difference?
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From: Hudson,Michigan
The way I understand it is that the bigger injectors are needed when you have modified it enough to need more fuel than your stock ones can put out.Like if you had a cam and bigger valves or some kind of heavy engine modifications.Your electronic fuel injection will only go so far no matter what size injectors you have.They only have to be large enough to handle the max that the system can put out.Some of the guys on here can put it in better detail than I can.One thing is for sure,it's a costly move for no benefit.I replaced my intake gasket on my '96 with 163k (caused by a missing support bolt on the plennum side)and I just put new o-rings on the injectors and they are running just fine.There are also places that recondition them a lot cheaper than new ones.
Last edited by 300 Buster; Sep 21, 2009 at 12:11 AM. Reason: added to reply
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From: Coal Region
if the engine is stock leave the #14s in. to properly use #19s u will need an adjustable fuel pressure regulator and dial it in. stock the 300 runs the fuel pressure from 45-60 PSI to overcoming vapor lock due to the fuel rail/manifold placement. running #19s at the high of a pressure, all u will do if run it pig rich.
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From: Gateway to the West
For give my interruption but I am researching 4.9 performance mods right now and read an article about doing exactly what WYG SS is talking about. I understand the concern over fuel pressure differences and potential vapor lock given that the fuel rail runs down the same side of the engine as both intake and exhaust ports. The obvious pressure differential between the two injector types shows that the Ford engineers were aware of this when they designed the EFI version of the engine. The question that I have is this though, "With two fewer cylinders which are significantly larger in bore, but so close to its barely 1.5 cubic inch larger V8 cousin in displacement, what (OTHER than the fuel pressure issue) dictates that the 4.9 (300) cannot handle the additional fuel input that the 5.0 (302) is equipped with from the factory?"
Is the efficiency of two fewer spark plugs that significant that the increase input from 19lb injectors will send it into a destructive rich condition that cannot be compensated for? After all, there are two fewer injectors as well. Just my own curiosity getting the better of me folks.
Is the efficiency of two fewer spark plugs that significant that the increase input from 19lb injectors will send it into a destructive rich condition that cannot be compensated for? After all, there are two fewer injectors as well. Just my own curiosity getting the better of me folks.
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From: Hudson,Michigan
From what I understand,the engine will run the same because the computer will adjust it to the same mixture,it will sense the extra fuel and cut it back.If the engine was ported and polished with a cam or other mods that could lean it out by breathing,then the computer would try to richen the mixture and my be limited by the injector size,so a bigger injector may be needed.I think the 4.9 may take smaller injectors than the 5.0 because of its terrible porting and the stock exhaust.Some of the guys on here can correct me if I'm wrong,that's just the way I understand it.
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From: Coal Region
if the engine is stock leave the #14s in. to properly use #19s u will need an adjustable fuel pressure regulator and dial it in. stock the 300 runs the fuel pressure from 45-60 PSI to overcoming vapor lock due to the fuel rail/manifold placement. running #19s at the high of a pressure, all u will do if run it pig rich.
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From: Hudson,Michigan
Sorry optikal illushun,I didn't catch that first part about leaving them in.Guess I should have read it a second time.My brain fart.
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well when i got the injectors out of the junkyard a searched the number online and seen that they were 20#. but when i start my truck up it will blow black smoke until it adjusts. im going to replace my o2 sensor cauase i think it is bad. dont know if it was replaced before or not. but it will run fine when it adjusts. i want to mess with the timing cause it is idling at 800rpm. now i got it at 14degrees btdc. can i adjust it to try and make it burn all of the fuel in the cylinder and what would i put the timing at. i got a msd coil and autolite plat. spark plugs.
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fi info
hi wygss paul from f/s here, it might be worth your time to check out rjm inj co. i got this site of the 335 forum and ill tell you what. i sure learned alot. the man is dedicated to ford fuelies and he does mention the 4.9. i heard 17 lbs in the 6 somewhere good luck. paul md.
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if i reprogram my truck for the 20# injectors would i maybe have a little more power or should i keep the 12# for mpg, or would the 12# probably be around the same power?
would it be hard to reprogram the injector part of the computer. i do know a little about computer stuff. if i would do this i would actually go to a junk yard and get a test ecu so i have mine for backup.
if i reprogram my truck for the 20# injectors would i maybe have a little more power or should i keep the 12# for mpg, or would the 12# probably be around the same power?
would it be hard to reprogram the injector part of the computer. i do know a little about computer stuff. if i would do this i would actually go to a junk yard and get a test ecu so i have mine for backup.
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From: Hudson,Michigan
You haven't increased the air flow or the exhaust flow,so why would you want to push more fuel in? A well tuned engine has everything balanced,same going in ,same going out.If you had modified your exhaust and intake to provide more air and better scavenging,then you would need more fuel,to get optimum power and you would realize better performance.If you haven't done any of this,you will end up just pouring more fuel down the hole.Your computer is already picking the best tune for you,if you reprogram for more fuel it would be like increasing the jet size in a carb on an engine that is already dialed in.Maybe if you want a little more power,you should look at better exhaust,air intake,then the bigger injectors and a tweek to the computer.Just my thoughts.
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From: Coal Region
opening the exhaust and increasing the air flow (by what small means a bolt on would yield) wont justify the amount of fuel larger injectors will provide. unless u open up the engine and go internal u are wasting ur time.
and, u'll need an adjustable fuel pressure regulator to properly run the larger injectors when the time comes.
at the fuel pressure the stock #14s are running at, they are injecting the same amount of fuel a set of #17s would at a normal pressure.
and, u'll need an adjustable fuel pressure regulator to properly run the larger injectors when the time comes.
at the fuel pressure the stock #14s are running at, they are injecting the same amount of fuel a set of #17s would at a normal pressure.
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ok ive put stock injectors back in my truck and truck ran like crap. so i suspected cyl #3. a couple days before it went i have a mechanics stethescope and heard that it was saying open longer tnat the other ones and it was probably on its last days. so i stuck 2 of the 20# injectors on cyl 3 and 6, cause 6 was my cabon fouled cyl. now i jsut want to replace all of them at once with new injectors cause i want them to last and know that they will work. if stock is 14#. https://fordsix.com/forum/viewtopic.php?f=2&t=22196
and i read some where where 17# would also work at the fuel pressure the stock #14s are running at, they are injecting the same amount of fuel a set of #17s would at a normal pressure.
and summint racing is cheaper than buying from auto store and i cant find 14# on the website. my question is,
would 15# or 17# work? ive found the lowest 15# on summit racing and now i read about 17# bing the same flow rate as 14# would the 17 work
and i read some where where 17# would also work at the fuel pressure the stock #14s are running at, they are injecting the same amount of fuel a set of #17s would at a normal pressure.
and summint racing is cheaper than buying from auto store and i cant find 14# on the website. my question is,
would 15# or 17# work? ive found the lowest 15# on summit racing and now i read about 17# bing the same flow rate as 14# would the 17 work