It runs smooth when it starts up on high idle, then as it warms up, you can smell that its running rich and idles rough. The check engine light is not on and the car had sat for about 2.5 years with a dead battery.
Was the fuel drained out and flushed ? The engine coolant temperature sensor may be bad and reading too low causing an overly rich mixture .
I just bought it, the fuel tank was reading empty so I added fresh fuel and some fuel system cleaner. I know I should have flushed the tank... Thanks for the tip, it also had a new transmission installed before it sat so long. It was shifting funny as well. The advance trac off, traction control is on the information center. Do I need to re flash the pcm and abs modules from having sat with a dead battery?
Unless a module has been replaced it should be OK but when a battery is unhooked some modules relearn information . MAP sensors can also cause over rich conditions if out of calibration .
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SOURCE: 1989 honda prelude enigne idles high then low irratic
I had the same problem on a Rover. There was a leak in inlet manifold that was caussing the problem.
To verify, spray some sealant to temporarily seal the inlet manifold .and the eratic idling should disappear for some time.
If it does, you know there is leak in inlet manifold which you can take of and refit with a new gasket.
SOURCE: Rough idle until warm 22r
if it is a carburated engine it is probably the a.a.p. diaphragm in the carb. if you remove the air cleaner and look on the side of the carb that is towards the valve cover near the front yow will see a vacuum hose going to a cover that is fastened with 3 screws. if you pull the vacuum line off you will see that there is probably fuel being sucked into the line due to the leaking diaphragm. the vacuum source is temp controlled and cuts off when warm. but when cold sucks fuel directly into the intake. remove the 3 screws to replace the diaphragm, being carefull of the spring. good luck!
SOURCE: 87 Supra idles rough and dies out
I would suspect a vacuum leak. At idle under high vacuum the air fuel mix is being leaned out until you have misfiring so bad the engine quits. The exhaust smells rich because even a lean mixture, if it doesn't light off, if full of unburned fuel. At road speeds, the vacuum is low so the engine doesn't care if there is a small leak somewhere. It is getting most of its air through the open throttle. Check all your vacuum lines but remember that even if every line is okay, it could still be leaking from an old cracked intake manifold gasket.
SOURCE: Check engine light is on in 2004 Lincoln aviator
Go to Wal-Mart or Auotparts store and buy SEAFOAM. This will clean & clear the crud off of your O2-sensor. This should strighten your problem.
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Leaking fuel pressure regulator diaphragms can cause a rich rough warm idle also .
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