Ive recently had a oil change and all spark plugs changed. In the morning when I start the car it idles over 3000 and lets out quite a bit of smoke out, a few minutes later the idle will drop below 1000 and the smoke will clear. When the car is parked it will still smell for quite sometime. It doesn't smell near the engine only at the back of the car
If valve guides worn an overhead cam oil leaks on top of pistons when shut off ,when starting will blow blue smoke till burned off......also if white smoke,could be head gssjet leaking coolant into combustion chsmber,less as heats up but constant.......if bad rings will blow blue smoke non stop ,usually.....if in cold climate when starting auoto choke would run at about 3000rpms when warm kicking down to a 1000......pretty normal
You don't mention what that smell is reminiscent of?
You don't mention the colour of the "smoke" and you didn't say whether the engine is petrol or diesel?
You don't mention whether the road behaviour/performance is normal?
White smoke is almost always steam or in the case of a diesel it could be an unburned fuel mist, grey/black is excess fuel and blue or grey/blue is burning oil.
Some steam is fairly normal until the engine and exhaust system is hot but excessive amounts could be one symptom of head gasket trouble. If the engine is drinking coolant and sending it through the exhaust as steam it will sometimes smell spicy.
Burning oil smells a bit like burned eggs in the frying pan.
If the car hasn't ultra-low sulphur oil and fuel the catalytic converter will convert sulphur traces into hydrogen sulphide - the bad egg gas...
SOURCE: 91 mazda 626 erractic idle surge when engine is cold
My '91 626 did the same thing. I tested the throttle position sensor, and it was good so that wasn't it. The other likely culprit is the Idle Speed Control valve, or Idle Air Control valve, which is a $500 part new (more than I paid for the whole car). I pulled one off a 626 at the salvage yard and got it for 3 bucks, put it on (it's an easy DIY, just 4 philips screws holding it to the intake manifold), however I can't be sure that solved the problem, since I haven't run the car much since then. It would seem the most likely cause, tho, and a cheap fix if you go used. Other possibilities: O2 sensor or Mass Air Flow sensor?
SOURCE: i have a mazda 626 with a idle problem
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