QuestionQUESTION: I am trying to find out what might be wrong with the car before I take it to the dealer. The car runs fine except at idle. Sometimes it feels like it shudders/sputters like it is going to die. It never has, nor does it do this all the time. I am noticing it occurring more often. Used to only be once or twice every week or so, now at least once a day. 60,000 miles, regular oil changes. I thought it may just need a tune-up, but wanted to know if it could be anything else? Thanks.
ANSWER: Hi Tiffany,
A "tune up" is a bit old fashioned and would open the door for a 'fishing trip' by a mechanic who is not ethical. The best thing to do is take advantage of the on-board diagnostic capability of the engine control system which will tell you by fault codes it has stored what is specifically wrong, in all likelihood. Turn the ignition key 'On-off-on-off-on and leave on' doing that in 5 seconds or less elapsed time. Then watch the odometer window on the cluster to see the miles change to show 4-digit numbers prefixed with a P. Then write back and tell me numbers and then we can figure out exactly what needs to be "tuned up".
Roland
---------- FOLLOW-UP ----------
QUESTION: Thank you for the prompt reply. I said "tune-up" assuming the way it was idling had something to do with it mis-firing. I used to work on a lot of muscle cars when I was younger and that was usually the problem. I did as you asked, but all it said was "done". I received no code. I did it 3 times to make sure.
ANSWER: Hi Tiffany,
"Done" means there are not fault codes in the computer. That leads me to suggest that you take a look at the egr valve as that one will, if sticking slightly ajar, cause a too lean mixture at idle. You didn't mentionwhich engine so I can't be specific as to location or design. But if you have the style with a visible valve stem try spraying some WD-40 on the stem where it enters the valve body. Then use the tip of a screwdriver in the stem's slot to loosen up the action so it closes tightly via its internal spring to dead stop.
That may solve the intermittent idle problem.
Roland
---------- FOLLOW-UP ----------
QUESTION: It is a 4 cyl, 2.4 liter. If you would know the location of the valve, I will give it a check. Thanks again.
AnswerI don't have a manual so new as an '04 but if you have an egr there would be a small pipe starting from the exhaust manifold that routes back to near the throttle body and in that pipe would be found the egr valve which has a round top and a vacuum line attached there to. The body of the valve is in the pipe and the pipe ultimately dumps into the intake manifold. You will see between the round top of the valve and the body a flange in which the valve stem can be seen along with its slot that I described.
I can't be sure whether the '04 has one but if not then you might check as well the positive crankcase ventilation valve which might also if flaky cause a miss at idle.
Probably most helpful remediation would be to clean the throat of the valve body, the butterfly plate (both sides) and the idle air passageway that by-passes the throat on the side. If any of those items are oily/dirty it can make for poor idling as well.
So start there, check the pcm and egr and I suspect you will solve your problem.
Roland
