Idle dip on SE

[blackster]

Ive spoken with another mechanic who works 5s and has stated that the above is normal when a increased electrical load is going through the alternator the idle stepper kicks in to correct idle drop.

Idle droop/dip/drop is not normal on any MX-5. The process the mechanic stated happens instantly and you'd barely notice any movement of the tacho let alone hear/see/feel an idle change of 200 RPM.

You may have a sticking/slow system component or an electrical problem.

The car has gone to see the auto electrician this arvo. Idle dip of about 50rpm occured then back to normal when lights came on, hardly noticeable. 100rpm drop then returning back to normal when the fan came on. According to the sparky they were both normal. Battery was checked it was normal.

Mania = Normal
Sparky = Normal
Mazda dealer = If your having 200rpm drop check battery, although the above findings sound normal. Bring the car in after NYE, will put the car onto the PC to check the PTCU. Which ill do.

[Alf]

Nope, mine doesn't dip under the situations you suggested.

The only thing common among the stimuli that cause your dip is a large change in current draw. On a weak or undercharged battery, or with a high resistance in the circuit, such as a loose or corroded battery connection, connector or fuse, this will cause a dip in the voltage at the front of the car.

I'll have a look tomorrow at what sort of voltage dip I get under similar circumstances and you can compare.

Cheers,
Alf