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Smoke?

Centrevillemx

NAXJA Forum User
My engine smokes for around 2 min when I start it ad then it goes away. Is this just Choke Smoke or is something wrong here?
 
What color?

Blue smoke is oil smoke. White-ish smoke isn't smoke, it's steam, indicating a coolant leak or a blown head gasket. Black smoke is carbon, indicating a probable rich condition.

If it's blue, you may need valve seals. Those are little rubber or plastic "umbrellas" that fit around the valve stems to prevent oil from running down the valves into the combustion chambers. If they are failing, oil can seep down along the valve stems when you park it for a length of time, and then that oil gets burned off when you fist start the engine.
 
BTW -- you don't have a choke. Electonic fuel injection, remember?
 
But doesn't it still feed a higher rate of gas during the first few minutes? Isn't that effectively a choke?
 
Ummmm, well ...

No, it isn't. Yes, the EHI runs a pre-set, rich mix during warm-up. No, it isn't a "choke," because a choke is a mechanical device in carburetors that closes down the size of the air passage. The purpose is to cause a rich mixture, but doing it with an electronic fuel map isn't really a "choke."
 
The cold enrichment on an XJ isn't usually enough to cause much if any smoke. A couple of possibilites are:

Leaky valve seal - oil drops into one cylinder, and burns off on start. Smoke will be blue, and it might not happen every time.

Leaky injector - gas dribbles from an injector which doesn't shut tight, burns off on start. Smoke will be blacker, and engine might run rough until it clears.

Bad head gasket - coolant is drawn into one or more cylinders as they cool. Steams off on start. Smoke will include steam and be light colored, and smell sweet. Coolant level will go down, but a small leak might not show that much for a while.
 
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