High idle when hot - na6

kazjim · Postby **kazjim** » Sat Jan 01, 2011 8:12 pm

G'day all, odd problem here ....

When my engine gets hot - say a 10 min drive - the idle sits around 1800 - sometimes (well, more often that not now ...)

Today i removed the throttle body, cleaned and lubed the idle air bypass and loosened off the dashpot (not even sure what that does .. looks temperature related ..) even lowered te 'normal' idel (oops - too low as it turns out!)

Any ideas what else to look at ?

Cheers
JB

clubman7 · Postby **clubman7** » Mon Jan 03, 2011 6:04 pm

Could try the PCV valve.
Maybe look around some vacuum hoses too.

phaedo · Postby **phaedo** » Mon Jan 03, 2011 6:55 pm

Try this topic to start with viewtopic.php?f=29&t=24399

kazjim · Postby **kazjim** » Mon Jan 03, 2011 7:59 pm

Thanks Guys, yep, pretty definitely the ISCV ...

email sent to Mania and mx5plus ... lets see who gets back to me first

Cheers all
JB

manga_blue · Postby **manga_blue** » Wed Jan 05, 2011 11:47 am

I just fixed a high idle problem in an Astina. These had the same idle system as the NA6.

Basically there was a fair bit of scale (rust) in the cooling system. The scale had blocked all the ISCV components and the small hoses leading to and from it. This meant no coolant flowed through the ISCV and hence it had no idea that the engine was hot until it eventually soaked up enough heat from surrounding radiation. Dismantling and cleaning all components and replacing the little hoses fixed it.

Dorimx5 · Postby **Dorimx5** » Tue Jan 25, 2011 1:13 pm

couldnt one of the temp sensors the one that goes to the ecu not the dash cause it cause i thought once the car reached proper operating temprature the sensor sends a resistance to the ecu lowering the idle?

93_Clubman · Postby **93_Clubman** » Wed Jan 26, 2011 10:07 am

Dorimx5 wrote:couldnt one of the temp sensors the one that goes to the ecu not the dash cause it cause i thought once the car reached proper operating temprature the sensor sends a resistance to the ecu lowering the idle?

when that sensor goes it usually results in rough idling (low idle) until warm.

jerrah · Postby **jerrah** » Thu Jan 27, 2011 4:00 pm

Vacuum leak maybe? If you unplug the idle control does it change the RPM?

DaveWA · Postby **DaveWA** » Thu Jan 27, 2011 5:22 pm

Possibly High ambient idle??

if you have touched your accelerator cable this might be a prob
also a quick job so easy to eliminate as a probable cause

easy fixed

http://www.miata.net/garage/KnowYourCar/S7_Idle.html

best of luck

kazjim · Postby **kazjim** » Sun Jan 30, 2011 10:14 am

Thanks all, jsut letting you know that its now all fixed

a replacement throttle body / iscv from MX5Plus in QLD has helped bring the idle to a sane level hot or cold !

bitch to change in this heat, but all good now

Cheers

Ollygt · Postby **Ollygt** » Sun Jan 30, 2011 2:28 pm

Hmm, so is it worthwhile to clean this puppy out if I'm doing some maintanence?

93_Clubman · Postby **93_Clubman** » Sun Jan 30, 2011 4:21 pm

Ollygt wrote:Hmm, so is it worthwhile to clean this puppy out if I'm doing some maintanence?

yeah, but careful what you clean it with, as it's easy to damage the brown coloured sealant on the inside of the TB where the throttle butterfly seats itself when throttle is closed.