Stall when stopping in cold weather

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For the past few weeks, my 91 Miata stalls when the engine is cold.
However, it only seems to happen when I hit my first stop sign of any
trip. As I brake toward the intersection and engage the clutch, the
engine winds down and stalls. To get started again I have to turn-over
the engine for 10-30 secs before it starts again. Any suggestions? It's
getting old, stalling in the middle of intersections!

Thanks for any help!


Re: Stall when stopping in cold weather


snipped-for-privacy@gmail.com wrote:
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Is the car starting and running normally otherwise and are you getting
any engine fault codes?
Also, can you duplicate it by coming to a stop in your driveway or does
it only happen after it has been driven a short distance? Does  it ever
happen more than once?

Finally, are you in an extra cold area?

It sounds like some type of electrical contact that is either sticking
or not making full contact until things warm up, but it is strange if it
stalls one time only and then runs normally right after that.

The fact that it is taking 10 to 30 seconds to start after stalling
would have me looking at the fuel delivery & ignition system first.

Pat


Re: Stall when stopping in cold weather


My '90 shop manual has some suggestions. They may not fit your symptoms,
but I'll post the gist of it FWIW:

The description is:  Engine starts normally but vibrates excessively and
stalls at idle before warm-up

The "trouble shooting" hints are:

1.  Low intake air amount - could be caused by an idle speed control
malfunction, air cleaner element clogged or airflow meter stuck
2.  Air/Fuel mixture too lean - caused by air leakage of intake air system
3.  Poor atomization of fuel - Low RVP (summer) fuel used in cold weather

There are a lot of electrical checks (to see if the ECU is bad)-

a vacuum check should show >450mm/Hg (17.7 in/Hg)

Make certain the air filter element is not dirty.

Disconnect the idle speed control valve at idle when cold and note the
idle speed. The engine speed should not decrease when hot (I
assume...with the connector left off..it's not as clear as it could be)

Check the air valve (probably a procedure on line someplace)

Replace the ECU and if that doesn't fix it....

Change to another brand of gas.


Another potential bit of help:  Engine unexpectedly stops running while
decelerating or after deceleration.

Hints are:

1.  Idle speed control malfunction
2.  Fuel cut control malfunction
3.  Engine feedback control malfunction
4.  Idle speed misadjustment

A bunch of electrical checks are listed pretty much as before

Check Oxygen Sensor (!)

Idle Speed Control valve (should hear a "click" when the connector is
removed (presumably when it is warmed up)

Set idle properly

O2 check and idle set are probably on line

Hope this helps...good luck

Ken

snipped-for-privacy@gmail.com wrote:
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Re: Stall when stopping in cold weather


snipped-for-privacy@gmail.com wrote:

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Check the base idle speed - should be 850rpm +/- 50rpm.

Also check for leaks in the servo vacuum hoses.

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