Need some help. Just picked up a '94 5.0/5spd. She's got a new rear with 3.73s, K&N, a 70mm Granatelli MAF, FMS 24 lbs. injectors, Flowmasters, and a Hurst shifter…that's it. She ran terrible when I brought her home. I've done the tuneup (cleaned the K&N and throttle body, new plugs, wires are good, PCV, fuel filter, cap, rotor...you get the picture, but she still was hard starting and NO POWER WHATSOEVER. She falls flat on her face at all speeds. No check engine light. I checked the timing...it was WAY off (like 3 deg...surprised she ran at all). I set it at 13 deg. That really made a difference, but still slugish. I figure now the problem is too much gas...after all, it's a stock TB and intake/exhaust manifolds. My plan is to eventually replace the exhaust, upper/lower, and TB but not right away. I figure the 24 lbs. injectors will be alright after those mods, but for now they're a lot...I need an adjustable regulator. So, I'm ordering it this week. What pressure should I expect the car to need? Can I get by with dropping the pressure, but keeping the 24s in until the mods are done? Thanks in advance...
Fuel Pressure Question
- Thread starter bn536
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Rootus
Officially Addicted
Fuel pressure is a short-term fix, the computer will adjust around it. You don't want too low a pressure anyway, it'll just make the problem worse. As long as the MAF is correctly "calibrated" to support the 24's, you're fine with them. Do you know it's fuel related? What kind of mileage are you getting? It would have to be in the neighborhood of 10 mpg to make a big impact on performance.
Dave
Dave
The MAF is calibrated for the 24s. I'm currently getting around 12 mpg...The big reason for my question is I want to make sure the regulator I buy is capable of adjusting low enough (if necessary). For reference, I'm leaning towards Accufab.
Also, what's the difference between the 19 and 24 lbs. injectors? Is it the amount of fuel that is sprayed with the same spray configuration or is the spray pattern of the fuel different. My concern is I won't be able to get the car running (good) with the 24s until the mods are done. If the 19s and 24s are the same pattern, then I would think I can lower the pressure and be alright, but if there's a difference in the way they spray, I may need to swap the 19s back in.
Also, what's the difference between the 19 and 24 lbs. injectors? Is it the amount of fuel that is sprayed with the same spray configuration or is the spray pattern of the fuel different. My concern is I won't be able to get the car running (good) with the 24s until the mods are done. If the 19s and 24s are the same pattern, then I would think I can lower the pressure and be alright, but if there's a difference in the way they spray, I may need to swap the 19s back in.
Rootus
Officially Addicted
The difference between 19 & 24 is the amount of fuel they will deliver at the same pressure when opened for the same length of time. If you lower the pressure enough, the fuel won't atomize properly. Really, the computer should be able to handle it, provided 1) your O2 sensors are functioning properly, and 2) your MAF curve is at least close. I have an AFPR, but in retrospect I think it was a complete waste of money.
Dave
Dave
You mentioned O2s, but what about one, or more, of the stock cats (120k on the clock) causing the problem? This is the first Mustang I've driven that I've had cats on...typically I've put an offroad H pipe on before I would have to deal with this problem, but I'm short of cash since I just bought the car. What are symptoms of a bad catalytic convertor...guess it's time to run a search. I haven't considered problems other than the fuel pressure because I've been convinced that was my problem.
Also, wouldn't the check engine light be triggered by cats or O2s?
Also, wouldn't the check engine light be triggered by cats or O2s?
