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I have a 98 Intrepid in impeccable shape and love the car. It has a 3.2L motor. It sometimes starts rough (sputter.. missing) when warm or cold (especially when pointed uphill). It will start immediately but idle rough until i give it gas and rev it up. After five to ten seconds it corrects and always runs smooth as silk on the road...this happens occasionaly but recently is occurring more and more. There is no check engine light on so my mechanic says he cant diagnose it. . .. The car has about 140,000 miles on it.. (235,000 kilometers) .. most people would say junk it.. I say I can get another 100,000 miles out of it easy... I am new to the forum and appreciate any help you can offer. Thanks
 

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Just because there is no check engine light does not mean there is no code stored. You can check fault codes yourself with this method:

http://www.allpar.com/fix/codes/index.html

These symptoms can also be from a dying battery, or poor battery connections. After checking for fault codes, remove and clean the battery terminal clamps, and clean the posts, and inspect where the wire insulation meets the clamps, for corrosion. Reconnect the battery and check voltage with a digital multimeter with engine off. Then have someone monitor the voltage while you crank. It should not drop below about 10.5 volts while cranking. And once started, it should read about 14 volts across the battery. Let us know the results. And welcome to Allpar!
 

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Do you still have the original wires on the car? If so, you might try replacing them. I've seen old plug wires cause a lot of strange things.
 

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This vehicle has COP (coil-on-plug), so there are no conventional spark plug wires. However the COP rubber plug boots can deteriorate and arc over time. Arcing will cause misfire and appear as thin gray streaks on the outside white porcelain body of the plug.
It is interesting that this happens when parked pointing uphill and makes me think that there is something wrong in the fuel tank, like the fuel pump that may be sucking air. The air bubbles will end up in the fuel rail at the front fuel injectors and cause misfire.
You don't need a 'ck eng' light to be on for a good scan tool to read 'real time' misfire and to identify which cylinder(s) are misfiring. That may be found under the OBD II misfire monitor screen.
If air bubbles are suspected, you can first test for correct fuel pressure and then take a sample of pumped fuel into clear soda bottle. The fuel stream out of the hose end should be liquid fuel with no bubbles or foam. You may want to try this before the first start of the day. Use care when handling exposed gasoline.
If this is the only problem with the car, it's a keeper.
 

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How old are the sparkplugs?
Does it smoke when started? (puff of blue or white smoke)
 

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It sounds like a possible injector/carbon issue. If you have a slightly leaking injector, that fuel will collect in the cylinder when the engine is off and cause that cylinder to miss when first started. You should also see some smoke due to it. Hook a fuel pressure gauge to the rail and see if it bleeds off after engine shutdown- if it does, pull the rail and inspect. Carbon buildup on the valves can also cause a similar problem. A good quality fuel system service should remove this buildup inside the engine.
 

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Discussion Starter #7
How old are the sparkplugs?
Does it smoke when started? (puff of blue or white smoke)
thanks for the reply.. it does smoke in colder weather.. last winter was always smoking and dripping water from the exhaust.. but not buring oil.. I will try changing the sparkplugs and see if that works.. thanks again.. Larry
 

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thanks for the reply.. it does smoke in colder weather.. last winter was always smoking and dripping water from the exhaust.. but not buring oil.. I will try changing the sparkplugs and see if that works.. thanks again.. Larry
Im asking for a short burst of smoke under startup and a few seconds after, what you describe
is just normal when its cold.
 

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Keep the spark plugs in order after removing them. They may tell a story if the tips are in different conditions as to which cylinder(s) have a problem. Black tips would indicate carbon fouling from possible rich mixtures.
You have the 100,000 mile platinums. Replace them with the same make (Champion?) and types specified on your underhood label.
 
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