Rough Idle, otherwise running well
02-14-2008, 12:36 PM
#1
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Rough Idle, otherwise running well
Hey guys I had noticed that my car had been idling some what rought (dropping between 800rpm and back up to 1k). My check engine light eventually turned on after a few days. I read the code with a scanner and it crossed over to "Random Cylinder Misfire". I put fuel treatment through the car on a brand new tank of fuel and drove fifty miles. I then disconnected the negative battery cable for a while to reset the light and ECU. When I started the car the code was obviously gone and the car was running noticably better. Now it is starting to idle roughly again. Would you diagnose this as possibly bad plugs. I replaced them about 1 year ago, but was thinking of replacing them as my first step toward recovery.
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02-14-2008, 03:45 PM
#9
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Originally Posted by INDYMAC,Feb 14 2008, 03:18 PM
This could be any number of things. Why don't you take it in to Billman to have it looked at.
On a MY01 there is a better way to reset the ECU. You remove the no. 25 "backup" fuse from the cabin fusebox for 60 seconds.
Reseting the ECU won't stop the engine from misfiring.(disclaimer)
Whenever the ECU is reset you are supposed to perform the "Engine Idle Learn Procedure". It is a "learning" ECU. So whenever you reset them, regardless of whether you actually perform the Idle learn procedure, they idle rough for a little while. (even stumble on occasion)
Hope any of this helps. Good luck.
02-14-2008, 09:35 PM
#10
Originally Posted by slates74,Feb 14 2008, 01:36 PM
Hey guys I had noticed that my car had been idling some what rought (dropping between 800rpm and back up to 1k). My check engine light eventually turned on after a few days. I read the code with a scanner and it crossed over to "Random Cylinder Misfire". I put fuel treatment through the car on a brand new tank of fuel and drove fifty miles. I then disconnected the negative battery cable for a while to reset the light and ECU. When I started the car the code was obviously gone and the car was running noticably better. Now it is starting to idle roughly again. Would you diagnose this as possibly bad plugs. I replaced them about 1 year ago, but was thinking of replacing them as my first step toward recovery.
But they're a little pricey, so I'd clean the MAP sensor and the IAC. Don't forget the channel between the MAP and the intake body.
Plugs and coil packs are the next cheapest things to replace.
But the injectors have been known to fail and give the P1399, P0301-2-3-4 codes. Cleaning them may or may not help.