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454 Mag MPI limits to 4100rpms lost 8mph too!

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Old 08-14-2010, 10:42 PM
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Default 454 Mag MPI limits to 4100rpms lost 8mph too!

Two months ago I was hitting the rev limiter easily, I haven't pushed the boat very hard at all, the last two weeks it's been limiting at 4100 mph, and I lost 8 mph. Nothing has been changed in the last two months. Seems a "lil" slugish, actually it's drives just like when I had my 3 blade out of the hole. Rams right up to 5100 when not in gear. I checked for off vacuum hoses and all plugs look good. Could it be a injector issue?

1998 454 MPI MAG
300HRS
24 hydro QIV
4800lbs
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Old 08-15-2010, 12:36 PM
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Doe sit actually feel like its hitting the rev limiter???? or just doesn't have the power to pull past 4100rpms????
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Old 08-15-2010, 01:43 PM
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I can't really tell, there is no mis-firing, nothing else seems to be wrong, the fuel pump is 1 yrs old, so I don't think that is the issue. It just climbs up and hits a wall.
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Old 08-15-2010, 02:43 PM
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The rev limiter feels like a constant miss. You would definately feel it.
I would just do a basic tune up or at least start by changing the fuel filter and inspecting everything else. Also, check the timing.
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Old 08-15-2010, 03:59 PM
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Nah, this feels like everything is perfect but just won't go above 4100, and it's ALWAYS 4100. I figured if it was a partial clogged injector, it would skip around a lil bit, but it doesn't.
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Old 08-15-2010, 06:50 PM
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4100mph is fukin flying man....how much faster you need to go?
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Old 08-15-2010, 08:30 PM
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Quote:
Originally Posted by Shorgasm View Post
4100mph is fukin flying man....how much faster you need to go?
C'mon, Mach 6 isn't enough, this is OSO!
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Old 08-28-2010, 10:48 AM
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I'm still having the same issue, I am stuck, I ramp up to 4100rpms and it just sits there, I'm stuck at around 57-58mph.

Beginning of the season I was hitting 5200rpms and 63-64mph.


Here is the break down:

Leak Down Test:
good
Compression Test:
good
Injectors working:
good
Injectors getting volt:
good
ECM:
good
Plugs (brand new):
good
Cap/Rotor (brand new):
good
Throttle body opening:
good
All wires to correct
cylinders on cap:
good
Fuel Pressure:
Good

Could it be my drive? I don't know where else to look! This SUXS X 10!!!

Last edited by bert4332; 08-28-2010 at 02:42 PM. Reason: Added fuel pressure
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Old 08-28-2010, 12:39 PM
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Check the fuel pressure.

Its not going to be the drive.
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Old 08-28-2010, 02:42 PM
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I forgot to add that, but yes it's good.
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