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Rough And Hesitent Idle

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Old 02-28-2005, 10:12 PM
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seandogg
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Angry Rough And Hesitent Idle

MY 8 HAS BEEN IDLING A LITTLE SHAKY AND ROUGH. IS THIS NORMAL FOR THE ROTARY ENGINE?
Old 02-28-2005, 10:14 PM
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Any mods to it ? & it depends how you define rough. It is not as smooth as an M3 idle, but it is not as rough as a Corvette's idle.
Old 03-01-2005, 07:20 PM
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Noticed mine idling rougher then usual today. Couple of times heard a slight popping sound like it was getting ready to kill it. This is the weirdest engine i have ever encountered. Some days it acts sluggish and other days it sits you back in your sit like it doesn't want to sit still. Run it hard and pull it in the garage and you can smell how hot it is. I hope its all normal.
Old 03-06-2005, 07:10 AM
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i have vibrations like every 1 -3 sec on idle at around 750rpm any reasons why?
Old 03-06-2005, 08:37 AM
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I think the general consensus on this board is that the idle can be a little shaky at start-up, especially in colder conditions because it is set-up to run "rich" to prevent flooding. But once the car is warmed-up, your idle should smooth out pretty good. There should be a little vibration in your shift ****, but that is normal. But the engine itself should not be vibrating or hesitating once warm. If it does, it could indicate you have an issue with your plugs. You also want to let the car idle for 10-15 seconds before you take off.

Anyhow, I think the best way to avoid any of these issues is to always insure that you run your car until it is very warm before you turn it off (ie. no 5-min trips, etc.). It's worked out great for me. I even had my car sit for multiple weeks due to winter and I am still able to get the car going with virtually no issues at start-up.
Old 03-06-2005, 11:45 AM
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Usually it will idle rougher when you have been driving around town. The plugs seem to foul easily......In mine 10Min on the highway keeps it running smooth. After a week driving back and forth to work...the car is trying to tell you it misses the buzzer :D
Old 03-06-2005, 01:06 PM
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The vibration i had can be felt even though after warming up and the vibration seems to come from the engine though. when you guys talked about the plugs, what happens to it?

oh yeah forgot about it needs a long crank to start, sometimes it starts like a beaut.
Old 03-06-2005, 03:14 PM
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I've had people ride with me claim that the idle is rough. But I've grown use to the...pip,pop....pip,pip...pop,pip,pop of the renesis. After 35000miles of this with no issues, I think it's normal :p . I don't know if this is what you're getting, but you may be used to the idle on other cars.
Old 03-06-2005, 04:08 PM
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Sean--What octane gasoline are you using? Your culprit may be lower octane fuel, which will certainly give you rough idle. Switch to 93 or 91 and you'll notice the difference.
Old 03-06-2005, 04:15 PM
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Originally Posted by boonyloh
The vibration i had can be felt even though after warming up and the vibration seems to come from the engine though. when you guys talked about the plugs, what happens to it?

oh yeah forgot about it needs a long crank to start, sometimes it starts like a beaut.
The spark plugs can become fouled with an accumulation of carbon material over time as the result of the incomplete burning of fuel. This usually happens over time when there is an over-rich environment such as that in the cold-start of an engine. In other words, the innards of the plug become coated with a dark carbon material that is electrically conductive. When enough of the carbon coats the center insulator, most or all of the electrical charge from the center electrode shorts to the insulator rather than jumping the gap to the other grounded electrode where it is supposed to go to cause the spark.

Therefore, in that case, there is inadequate spark to ignite the vaporized fuel. To complicate matters, as the engine is cranked over and over in attempting to start the car, the combustion chamber becomes flooded with raw fuel which can be too rich to ignite even if there was a spark.

Spark plug fouling is exacerbated by frequent cold start, short distance driving resulting in the engine failing to reach a temperature where the carbon is burned off. The solution is generally to remove the plugs and clean or replace them with new plugs. However, sometimes if you can get the car started somehow, a session of very spirited high-rev driving may actually burn off the carbon and at least partially restore the plugs to good working order. In fact, a little spirited driving once in awhile could be considered preventive medicine and just what the doctor ordered. :D
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