5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

computer rpm fuel shut-off

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Old 08-31-2009, 12:39 PM
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stanks347
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Default computer rpm fuel shut-off

I was reading in MMFF this weekend that the stock EEC-IV will shut the fuel off at 6,250 rpm. I am spinning my motor to 6,500 and I have not heard a ping or a pop. Does anybody know if this is only certain years or should I bring down my rpm limiter.
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Old 08-31-2009, 01:04 PM
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mattdel
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Running 24# injectors on a 9psi forced induction engine... you're already quite lean as it is.

I suggest you pickup a pair of 30#'s, at least, and then dyno tune it. Or better yet, go the other way around and see what the tuner recommends. Until then, I wouldn't go anywhere near that RPM range if I were you.
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Old 08-31-2009, 02:26 PM
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stanks347
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Yeah I know I am running it on the ragged edge. I am going to step them up on the next motor I am building (347). But no input on the cpu?
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Old 08-31-2009, 02:55 PM
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mattdel
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The PCM fuel cutoff is for all year ranges that had it, 86-95. Depending on your cam specs, you might not even be making power that high. A dyno tune is the best option here too, so you can see when you stop making power. If anything get an aftermarket ignition setup and put a limit at 6k, then you're at least somewhat safe.
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Old 08-31-2009, 07:48 PM
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mjr46
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factory tac is unreliable, your not that high I bet
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Old 08-31-2009, 09:11 PM
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93 LX FiveO
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stock tach is way off
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Old 09-01-2009, 11:14 AM
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stanks347
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I have my rev limiter chip in my MSD set at 6500. I have bounced it once or twice and the tach is reading over 7. I don't have a a/f/r guage or a tune shop within 100 mi. or so. I know I need to invest in these to get it dialed in but I am like everybody else... on a budget. Thanks to everyone for their input.
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