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Rough Idle when cold - 2001 Mazda Tributre

I have a 2001 Mazda Tribute with 150,000 miles that is meticulously maintained. This past winter (as far as winter goes in San Diego) the engine would run rough and the rpm’s would drop close to stalling when stopping at a light for the first 2 or 3 miles. After that the engine has warmed and there is no problem. Could this be the intake gaskets needing replacement or any other suggestions. This only happens on a cool or damp, rainly morning.

My first guess would be the ignition timing. On some cars — this is more of an issue on cars made in the 1990’s than the 2000’s, but it may be on yours — the ignition timing can retard over time, and what you notice is that it drops the idle rpm too low when the engine is cold. Colder weather would make this more noticeable.

A normal tune-up would catch this, that is if it is done correctly. It is easy to fix if timing is the cause, just a simple adjustment. Sometimes the mechanic gets a little lazy, changes the spark plugs, sets the warm idle speed, and doesn’t check the ignition timing.

There are other potential causes. Anything making the mixture more lean would cause this. Leaking gaskets like you mention, etc. And there is always some method used in te fuel injection system to increase idle speed and less-lean mixture as the car warms up, and that mechanism could be broken. That is also easily checked by an experienced mechanic.

Thanks for the suggestions. I’ll check them out.

Timing’s not adjustable on a 2001 Tribute/Escape. You have a coil pack. If your MIL is on have the codes pulled. If you have a P0171/P0174 then you are probably right on about the intake gaskets. The plastic intakes can leak when cold and seal up when warm.

The check engine light never comes on. My guess is the intake gaskets are worn but not to the point of triggering the codes before they heat up and seal. I think it would probably be worthwhile to replace the intake gaskets.

Before you just replace them, get a can of carb cleaner or use an unlit propane torch - when the car is cold feed some around the manifold. Best to figure out if there is a leak before all of the time/$$/trouble

Check your coolant temp and air temp sensors

Thanks for the suggestions. They’re appreciated.