Hesitant at high rpm

98BlackGT

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Ok so I posted on this before but my car is hesitsting at high rpm like 4500 when I'm gettin on it. It cuts for for a few seconds and goes back. I've done the following

New plugs
Checked fuel pressure
New maf

And a few other things I'm forgetting... Anyone have this problem/think they know what it can be? I'm hearing numerous things like fuel pump and fuel filter but I just changed the fuel filter 10k miles ago


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Musturd

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Yea but not the fuel pump , it could be losing fuel uptop at high rpm where I'm sure you didn't check fuel pressure under load, you just used a gauge and checked it under the hood ? It could even be ignition related .
 

Wild Horses

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Had the same exact problem but mine was the plugs. Have you gotten wires or made sure they have made positive connection to the plugs? Sometimes it's the simplest things. It does sounds ignition related. A set of wires if they're due, and if that won't clear it up I'd try fuel filter, then coil packs before fuel pump. First thing I always do is triple quadruple check all connections.
I messed with my old 5.0 for 2 days that wouldn't even start. Rearranged plug wires reset top dead center at one point thought my timing chain was broken. But nah the MSD negative lead was unplugged. Learned my lesson.
 

98BlackGT

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Had the same exact problem but mine was the plugs. Have you gotten wires or made sure they have made positive connection to the plugs? Sometimes it's the simplest things. It does sounds ignition related. A set of wires if they're due, and if that won't clear it up I'd try fuel filter, then coil packs before fuel pump. First thing I always do is triple quadruple check all connections.
I messed with my old 5.0 for 2 days that wouldn't even start. Rearranged plug wires reset top dead center at one point thought my timing chain was broken. But nah the MSD negative lead was unplugged. Learned my lesson.


I just did a full tune up 10k miles ago and checked over everything recently. So I'm starting to think it's something else
 

98BlackGT

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Yea but not the fuel pump , it could be losing fuel uptop at high rpm where I'm sure you didn't check fuel pressure under load, you just used a gauge and checked it under the hood ? It could even be ignition related .

Yeah I only checked it at regular idle
 

Wild Horses

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I just did a full tune up 10k miles ago and checked over everything recently. So I'm starting to think it's something else

You do have the dual coil pack set up right? I'd buy one if on a budget from a local parts store. Try it one side at a time. See how it acts. They usually don't fail at the same time. Find the side that's breaking down at high rpm. Return pack to parts store if no change. If you get even a little better then buy another pack and drive.

Its ts easier to go through the ignition components first to be sure then to start dropping gas tanks for nothing.
 

98BlackGT

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Yeah dual coil packs, I have msd in there now. I have msd wires too and had ngk plugs, switched out plugs for autolites
 

Wild Horses

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Yeah dual coil packs, I have msd in there now. I have msd wires too and had ngk plugs, switched out plugs for autolites

What did you gap those autolites at? I pulled some autolites out of my 98 because it was missing at high rpm, and they were almost melted. I got NGKs gapped em at .48 and the car ran like a top after.
 

Wild Horses

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It'd be ideal to get a look at at least one plug to see how it's gapped and burning.
 

98BlackGT

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Yeah once it gets nicer out here in NJ I'm gonna start going over it. There was not a big chance wen the plugs were changed though that's why I'm thinking it's definitely something else
 

Wild Horses

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Yeah once it gets nicer out here in NJ I'm gonna start going over it. There was not a big chance wen the plugs were changed though that's why I'm thinking it's definitely something else

Yea im in MD and it's Ben sub freezing for like 3 weeks. Just got 2" of snow last night.
 

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