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post #1 of (permalink) Old 01-23-2001, 05:06 PM
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Having 4.0 trouble

I have a '92 4.0ho and can't find all of my H.P. It runs good but ticks and has a slight whistle once past around half-throttle at freeway speeds. I had the injectors cleaned, replaced the fuel and air filters, new cap and rotor, new plug wires, and relatively new plugs. Is this a timing issue? Can I adjust the self-adjust timing manually? I'm pretty much at a loss.

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post #2 of (permalink) Old 01-24-2001, 08:17 AM
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Re: Having 4.0 trouble

Have you checked to see if your catalytic converter is plugged up? Just a thought....

Tommy B. in AZ -
More Guts than Brains.
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post #3 of (permalink) Old 01-24-2001, 01:45 PM
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Re: Having 4.0 trouble

Does it run better at low vs. high rpm? You mention a slight whistling noise at higer rpm, does that correspond to the missing HP? It could be a failing fuel pump if it doesn't have much top end to the motor (or filter, but you changed that). Maybe a loose crank sensor or wire. Very well could be a failing cat too. When was that last changed?

Have you been able to use the check engine light codes to diagnose the problem? Good luck and post again once you've checked out some more of these things.


258 4.0 Head/MPI,NV4500,D300,4.10's,HS9500
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