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I've had the car since September an it's over due for an oil change. It's starting to run rough. Is this normal? We're taking it in for an oil change and the hubby is scared there might be something wrong with it.
 

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There should be no connection between the two. How many miles since the last tuneup? Are there any unusual gauge readings or warning lights?
 

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Bob Lincoln said:
There should be no connection between the two. How many miles since the last tuneup? Are there any unusual gauge readings or warning lights?
No warning lights just runs rough. The last tune-up we had was in December.
 

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I should also say that we don't take it out for a run on the highway much. We just drive it around town. Everyone says that's the best way to kill a car.
 

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Just a rough idle or going down the road also? It may set a misfire code and turn on the 'ck eng' light after awhile.
Check spark plugs for carbon and make sure that the correct type (Champion RE16MC?) was installed along with a good fresh set of plug wires.
Around town driving shouldn't bother it too much as long as it can fully warm up. More frequent oil changes may be needed in stop/go type driving.
 

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ImperialCrown said:
Just a rough idle or going down the road also? It may set a misfire code and turn on the 'ck eng' light after awhile.
Check spark plugs for carbon and make sure that the correct type (Champion RE16MC?) was installed along with a good fresh set of plug wires.
Around town driving shouldn't bother it too much as long as it can fully warm up. More frequent oil changes may be needed in stop/go type driving.
A rough start and for a while, on the road. I'm in Canada and to me it goes away when the engine heats up. But the hubby is sensitive to the car and says it's still rough when running for a while. Back in Dec. we brought it to the garage to have a tune-up and it cost $500. and they put in new plugs. I never asked what they were putting in.

We got the car used back in Sept. and we never thought about how much it costs to get fixed. Thanks to some problems we had with our insurance company, we're now lacking funds to have anything major happen to the car.
 

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GottaPT,

If I read it right, you bought the car last SEP, noticed rough running by DEC, have not changed the oil, live in Canada, and it smooths out after it warms up.

Try changing to the recommended viscosity oil. It may be that before you bought it, somebody put oil in that was too thick. That may not be the issue, but would explain the symptoms well. Your ready for a change, so there's no extra cost.

Good luck.

Michael
 

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The more that you can do yourself, the more money you can save. Basic hand tools and spare time are the only real things you need. A service manual with pictures and procedures helps.
Cold weather can cause carbon-fouling of the spark plug tips, especially in short trip driving and worse with an incorrect plug. The #1 plug can be accessed without having to remove the upper intake manifold and a visual inspection may show a black tip. Get the name and # of the plug while it is out.
A thermostat problem may keep the engine cold for too long. If the coolant is old, you might want to drain and refill the coolant with fresh 50/50 HOAT antifreeze and distilled water.
A high-quality 5W-30 motor oil and filter change should also be done if needed.
 

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Discussion Starter #9
the oil change should have been done last month. It's not bad as far as a change goes. We're booked for 2pm today.
 

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I have 2006 PT with 90,000 and just after a tune up it ran rough. It turned out one of the plugs the mechnic put in was bad and needed replacing. After the plug was replaced it ran smooth - no problems.

IBCruzin
 

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It could be the egr valve is starting to stick a bit open but not enough to set a diagnostic code. If it
sticks a bit open the motor runs rough becasue of a lean condition.. A cold motor likes to have a bit
more gas or a rich air-fuel mixture. Once the motor warms up it is not a sensitve to the lean mixture.
Eventually the egr will stick enough to set a diagnostic code.

Hope this helps,

Gerry G.
 

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I've noticed as my oil gets old, one of the signs to change it out is a rough cold idle. Checking the dip stick it's looking below half and dark when cold but see through when warm.
It's a good clue to tell yourself, it's time to change oil, because if you leave it, it just causes more engine wear.
I never believe in that 7K engine oil change. I travel in town mostly too, and find it starts to do that between 3-5K. Depending on highway mileage.
If I traveled more highway, then the oil might last closer to 7K.
The thicker the oil the valves I think operate differently. I'm still under 70000 on my 2003.
 

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66coronet said:
I've noticed as my oil gets old, one of the signs to change it out is a rough cold idle.
The thicker the oil the valves I think operate differently. I'm still under 70000 on my 2003.
No, no relation. If you were to wait long enough between oil changes for the oil to be the cause of a rough idle, your engine would be about to seize. Rough idle would have another cause.
 

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Old oil that has a high concentration of unburned fuel and a strong smell of raw gas could cause a rich mixture as it is inhaled by the PCV. It will also thin the oil and cause poor lubrication.
The O2 sensor will try to compensate for lean or rich conditions, but with cold weather/short trip duty it may not come into play and reach closed loop as often.
You want to change oil more frequently in cold weather/short trip driving. Oil is cheap, engines are not.
If the engine is running rich because of misfire or skewed O2 sensors, you want to promptly remedy that situation before engine wear/damage occurs.
 

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I have an '08 auto base with a rough idle and it burns a quart of oil per month. 95% of the driving is short runs around town in a hot environment. Should I change to a different viscosity than 5w-30? It has fresh plugs and wires, new air filter, cam sensor, and idle air valve. No overheating issues at all and starts every time.
 

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Keep the recommended oil and change the PCV valve. For best results use only a Mopar valve.
 
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