I have a 92 Miata with almost 90k miles. The engine stalls sometimes when I engage the clutch and put the shifter into 1st gear. If I leave the shifter in neutral then no problem. Sometimes the engine doesn't stall but rpms drop very low but when I take the shifter out of 1st gear then back to normal.
Any ideas?
Check the clutch switch (above the pedal) as they almost always fail around this mileage; on a UK MX-5 owners' club tech day something like
80% were dead. You can normally fix them with the spring from a ballpoint pen, or just buy a new switch. If the clutch switch doesn't work the engine will cut the fuel supply just as it does on the over-run.Also flush out the idle air valve with throttle body cleaner (no need to remove it - just remove the rubber hose from the big air duct) and then, when the smoke has cleared (take it for a good run) reset the base idle speed to 850rpm. This is worth doing anyway, but will also eliminate the possibility of a sticky valve.
If it's also getting hard to slip into gear, time to rebuild or replace the clutch slave cylinder. It's leaking, and not allowing full disengagement. This is probably the most common mechanical failure on an NA...and the cheapest to fix.
UK models must be different, then. On North American NAs, the clutch switch is just a starter interlock.
We don't have a starter interlock over here. Fixing the clutch switch is known to cure "idle droop" when coasting to a halt or changing gear on ours.
There is another clutch switch that is above the pedal on N American cars.
Isn't that to disengage the cruise control?
It's connected to both the CC computer and the PCM/ECU. I am unsure of it's complete function.
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