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I have a 2003 clips with a 2.4 runs fine for about an hour then I started miss firing like crazy only under load runs find a neutral anybody have an idea what it is I’ve been told it could be the pressure regulator I’ve been told I give you the intake manifold I just wanna know exactly what it is before I go spending money on parts any ideas
 

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2001 Spyder GT. Koni adjustable shocks. cold air intake, ST sway bar.17X8.5 rims. LED headlights.
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In the past I have seen this on some other vehicles when the ignition coil starts to fail. When it would get hot it would start to misfire. It was a hard thing to diagnose the first time, but then it happened to a second similar vehicle. On both of those engines, the coil was mounted directly on top of the engine. Electronics and heat do not mix. You might check it out. ...J.D.
 

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Recently change spark plugs? I changed mine ages ago at one point with the fancy iridium plugs. Burned up 3 coil packs and switched back to the original copper style plugs.

If you didn't change plugs recently, swap the coil packs and check engine codes (assuming the CEL is on). If coils it will follow. Made my diagnosis easy at the time.
 

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Recently change spark plugs? I changed mine ages ago at one point with the fancy iridium plugs. Burned up 3 coil packs and switched back to the original copper style plugs.

If you didn't change plugs recently, swap the coil packs and check engine codes (assuming the CEL is on). If coils it will follow. Made my diagnosis easy at the time.
Were they perchance....Bosch spark plugs or some weird surface gap or multi-ground plug?
 

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2001 Spyder GT. Koni adjustable shocks. cold air intake, ST sway bar.17X8.5 rims. LED headlights.
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I have been an old hot rodder for years. Over time I have learned that the resistance of your secondary ignition [plugs wires, etc,] has to be compatible with the high voltage side of your coils or you will have problems. If the setup is designed for copper plugs, OR resistor plugs, also copper as opposed to resistor wires. you need to stick with what is original OR change out the whole thing, coil and all. That being said, I have seldom, if ever, seen and aftermarket ignition worth the expense of what you paid for it. This is one of those areas where fancy hardware does not make more horsepower. Just one old guys opinion. ...J.D.
 

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Ngk iridium. Multi ground.
If you want to dip your toes back into long life plugs again I'd suggest trying out some Denso Iridium Twin Tip plugs. Iridium center electrode and a single strap with a platinum electrode sticking off it. They're pretty much what all the newer cars are coming with now as they do offer a real benefit with less spark shrouding by the ground strap without making the strap smaller and more prone to get hot and cause knock. Overall the design is a win-win, NGK and several others have their own variations on the same design. They're honest 100,000 mile spark plugs with 120,000 miles not being out of bounds for them at all.
 

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2001 Spyder GT. Koni adjustable shocks. cold air intake, ST sway bar.17X8.5 rims. LED headlights.
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An automotive ignition coil is nothing more than a transformer running on a pulsed and timed 12-14 volt DC current. Power going in at battery voltage is raised to high voltage because of the turns ratio of the coil construction. The more wire windings in the output side [secondary] as opposed to the number of windings on the low voltage, the higher the output voltage. Low battery voltage can induce ignition misfire. Problems arise when you start changing plug types. Too much electronic resistance in the spark plug or plug wire can cause a misfire. That happens when the coil output is unable to overcome the resistance and deliver a clean spark. The plug AND wire have to have the correct resistance to work properly. Also, if the coil starts to break down, usually due to failing insulation on the wire windings inside, the spark will also deteriorate and cause a misfire. ...J.D.
 

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2001 Spyder GT. Koni adjustable shocks. cold air intake, ST sway bar.17X8.5 rims. LED headlights.
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Most likely in the high voltage side of the ignition. Sometimes, on some engines you can get a "lean misfire" where the mixture is too lean for it to fire properly, but I would think that pretty rare on a fuel injected engine where the ECU compensates for mixture variations. ...J.D.
 
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