mx5cartalk.com

Heya all,

Have been having some issues latley with the NA.....

When the car is warmed up and idling, the revs drop when i push the brakes or have headlights on.

For eg, if i sit at traffic lights, clutch in brakes and lights on, revs will drop and motor starts running quite rough like its struggling to turn over....then goes back to normal when i take my foot off the brake...the power windows also have the same effect too......would this be an alternator problem or something a little more major? I cant quite work it out as its only started happening recently. Feels like something is draining power badly

Cheers
Schultzy

It would be best to get it checked by an auto electrician. You may have some mystery short circuit happening there.

Sounds like an earth problem.

Check your terminals, and the earth strap from engine to chassis.

Is the idle set correctly in the first place?
My NA had a similar problem when I got it, the idle was not set correctly and the first time I used the lights the engine wanted to stall. See link about setting idle.
http://www.miata.net/garage/KnowYourCar/S7_Idle.html

If this already OK I would get an auto elec to check out.