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Discussion Starter #1
Hello I have a 1998 Mustang GT with a procharger p-1sc on it. I recently blew the motor so I had a new one built by modular mustang racing called the streed mod 600 block with low compression. The car ran awesome before it blew and now with the new block in the car the car runs awful sounds good though. My problem is what other modifications need to be done to the car with a blower on? Do I need bigger then 24 pounds injectors? I have an sct scanner and the codes say the car is running lean. I know I for sure need a good tune. Please help me out I am desperate to figure out why it is running so bad. Thank you all for the help!!!:bigthumbsup
 

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motor

Did you install the motor or did the shop?? If the shop did it did they not dyno tune it for you?? How much boost are you running? I just put 42lb injectors in my 98, I was told that I needed them for the boost I was planning on running, around 10lbs, Are you using the stock fuel rails and regulater, you may need a boost specific regulater.

I would say with the procharger and a built engine that you would need some bigger injectors the 24s. But I am no expert, still having some tuning issues with mine:scratchchin
 

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Discussion Starter #3
Yeah I thought 42 pound injectors was right. I had a guy that owns a shop do the car because I was kind of on a budget. I am running 10 pounds at the moment, the car runs great at idle and if you drive it normal but when you go to get into it breaks up. Can I use 42 pounders on stock fuel rails? Do I need to modify the fuel pump? Thank you!!!
 

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stock rails

Do you have a boost specific regulater though????? With a boost specific it will raise the pressure with the amount of boost you are putting down at a given time. I dont think you will get the fuel pressure you need in the higher rpms with the stock rails and stock regulater, at idle it would probally run fine but when you go under boost the stock setup is probally not putting out enough pressure. I think ford had three sets of rails and regulaters between 96 and 98, mine had the regulater welded to the rail, wouldnt work for my application.
 

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stock rails

You probally do need a bigger fuel pump and a boost specific regulater, sounds like when you get into boost you are going lean, probally do to fuel pressure. 96-98 need the regulater that is made for boost, without it you will never get the pressure you need.

I ran 5lbs of boost with 24lb injectors and a 255 fuel pump with the stock rails and regulater and it ran fine with a dyno tune, but when I changed to a smaller pulley and 42s I had to get a upgraded regulater, since my regulater was welded to the rails I just bought a kit.


I fell you pain
 

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parts

Whats the parts list for your car?? Mass Air? Fuel Pump? Computer upgrade? If you havent had any computer work done at all then I dont see how it runs period. BUT again im no expert, cant wait to get all my junk worked out.
 

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Discussion Starter #8
No I dont believe I do have a boost specific regulator? I am not sure the guy who sold me the car had a stock bottom end with the procharger with stock injectors with a 255 fuel pump. It ran 12.30's on drag radials it ran awesome I dont understand the 4.6 motors I always worked on the 5.0 without a blower so I am confused.
 

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Discussion Starter #9
mass air stock no computer work which upset me a little fuel pump isnt stock thats 255. so I need 42 pound injectors mass air boost regulator and a tune?
 

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well

If it ran 12.30s before then I would say it just needs a tune, if it ran like that without a bigger mass air and bigger injectors then I would just get it to a dyno
 

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procharger fuel pressure

i have a 96 with 12lbs and running 60lbs injs mine screams at high rpms but seems to run rich at low pms also had a k b boost up pump but it turned out to b useless so i installed a wp 255 and the pressure was there
 

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im not expert or anything however i was looking into the charger and i talked to a dyno expert.. he said some cobra injectors and a good flowing pump is good he says the rail wont need replaced unless running over 12 psi on the charger.. Also people on this forum told me to not romp on the gas untill you get a dyno... they said you need a good A/F mixture or your engine will run like crap. also leaning out your engine isnt good either so maybe take it easy.. Like i said im no expert but its just my oppinion.
 

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jcalvin is right you really do not want to run that engine hard with bad fuel pressure if it leans out to much you will burn up a piston and may have detination issues i would first and foremost get it on the dyno to see what its doing im running my stock rails for now
 
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