As itsa got a bit colder here in the UK now on the way to and from work I find my revs dieing on idle or pullign up to a junction stop.

Is the alternator on the way out as i have the lights on, heater blowing, stereo on runing 2 amps etc!

or is it a air leak somewhere?

 

if the volts are still near the 13-13.5 mark when everything is on then I would rule out the alternator.

 

Check the alternator belt tension. Check your vac at idle. Are the revs dropping and you stall or is it the annoying idle droop then recover?

 

yes they are. However If I turn the fan swith to 3-4 it will do down to 12/12.5!

 

It seems liek an idel droop that recovers. the car has not completely cut out.

with the stereo off, gheaters off and lights off..its seems fine.

Its a 14 year old car so dont know when the alternator has ever been replaced as i have had her for 3 years.

Could i use a higher amped alternator from a MK2 one and will it go straight on.

i can readily get them!

 

no i researched higher output alternators when i had a lot of stereo stuff in mine, the only real solution seemed to be have one rebuilt.

 

Sounds like it's time for a stiffening cap if you don't already have one.

 

I have this same problem... every time I turn on my headlights my idle actually drops then recovers. Its odd.

 

done some research on this at the miata.net forum.

It seems this is a common problem and is not necessarily battery/alternator related.

I have concluded from the research that it is either of the following:

- Blocked fuel filter
- Idle control valve needs adjustment
- Throttle boddy needs cleaning with carb cleaner

Any ideas?

i will be be taking the throttle body intercooler pipe off and cleaning the butterfly valve with carb cleaner.

 

mine would do that, but I'm N/A, it was the throttle body butterfly...it helped out a TON, just spray with cleaner, wipe with a rag if you can...spray some more cleaner...mine was...nasty as hell really lol.

Idle was fine...throttle response was even helped lol.

 

CURED!

no more idle droop....!

Did the idle droop fix in miata.net/garage/ignition!

 

what did you do, bump the idle speed up a bit?

 

yes indeed!