I need some advice here... Here is a ton of details.
Vehicle-
97 F150 4.6l, PI intake, Ported PI heads, custom crane cams, Accell coil packs and wires, 75mm TB, 80mm mass air, BBK fuel pressure regulator, headers, dyno tuned Diablo Sport chip, Made 300hp at the wheels when tuned. 77k on motor, 20k since engine work done.
Issue-
Misses under load. Improves at higher RPMs. I have to slip the clutch to get it moving in first. as the RPM goes up, I can apply more and more throttle. By the time I am at 3-4k, I can be at about half throttle. If I don't push it too hard, it runs smooth and strong. As I get past that point it starts missing a little, then it will fall completely on its face and bogs. I can let off the throttle till it stops missing and then roll on it again and it will run fine. It will even miss a little when I crack the throttle from an idle in neutral.
Fuel Pressure gauge doesn't show any drop in FP when it is running bad. A/F gauge doesn't show it going lean when it is missing (the gauge will look like it is "vibrating" as it swings back and forth when it is missing, let off and it will stop right away).
It was throwing an occational P0305 (cyl 5 missfire). I replaced plugs 1 and 5 last night. They both looked pretty good. drove it to work today and got a P0305 and a P0300 (random missfire).
I was sitting for a few years, I finally got the crappy gas out and filled with fresh gas and some fuel injector cleaner. It is running better than it was, but not right. I have replaced the TPS, cleaned the MAF meter twice, and very very carefully checked for any vacuum leaks (to the point that I even pulled the upper and lower intakes).
The engine runs smooth otherwise, so I think it is likely either a fuel or ignition problem, but am having a hard time determining which it may be. I don't want to throw a lot of cash at parts without being able to fairly confidently determine which it might be. I was hoping some fresh gas and injector cleaner would fix the problem, but it definately isn't "fixed".
Any advice is appretiated
-MrCarlson
02 GT (mild 4.6)
84 SVO (moderate 2.3T w/n2o)
71 Convertable (351c 2v)
69 Fastback (moderate 331 stroker)
97 F150 (4.6 w/mostly mustang engine parts)
Vehicle-
97 F150 4.6l, PI intake, Ported PI heads, custom crane cams, Accell coil packs and wires, 75mm TB, 80mm mass air, BBK fuel pressure regulator, headers, dyno tuned Diablo Sport chip, Made 300hp at the wheels when tuned. 77k on motor, 20k since engine work done.
Issue-
Misses under load. Improves at higher RPMs. I have to slip the clutch to get it moving in first. as the RPM goes up, I can apply more and more throttle. By the time I am at 3-4k, I can be at about half throttle. If I don't push it too hard, it runs smooth and strong. As I get past that point it starts missing a little, then it will fall completely on its face and bogs. I can let off the throttle till it stops missing and then roll on it again and it will run fine. It will even miss a little when I crack the throttle from an idle in neutral.
Fuel Pressure gauge doesn't show any drop in FP when it is running bad. A/F gauge doesn't show it going lean when it is missing (the gauge will look like it is "vibrating" as it swings back and forth when it is missing, let off and it will stop right away).
It was throwing an occational P0305 (cyl 5 missfire). I replaced plugs 1 and 5 last night. They both looked pretty good. drove it to work today and got a P0305 and a P0300 (random missfire).
I was sitting for a few years, I finally got the crappy gas out and filled with fresh gas and some fuel injector cleaner. It is running better than it was, but not right. I have replaced the TPS, cleaned the MAF meter twice, and very very carefully checked for any vacuum leaks (to the point that I even pulled the upper and lower intakes).
The engine runs smooth otherwise, so I think it is likely either a fuel or ignition problem, but am having a hard time determining which it may be. I don't want to throw a lot of cash at parts without being able to fairly confidently determine which it might be. I was hoping some fresh gas and injector cleaner would fix the problem, but it definately isn't "fixed".
Any advice is appretiated
-MrCarlson
02 GT (mild 4.6)
84 SVO (moderate 2.3T w/n2o)
71 Convertable (351c 2v)
69 Fastback (moderate 331 stroker)
97 F150 (4.6 w/mostly mustang engine parts)
