I have noticed idle dip on my NB 2000 1.8 litre when it comes to a stop, with the engine running ... like you do at intersections and traffic lights. After taking your foot off the accelerator pedal the revs will drop, perhaps as low as 400 rpm, and then go up to around 1,000 rpm (or more). This cycle may occur just once or continue for 2, 3, 4 or more times before the engine achieves a steady state around 900 rpm does anyone now to fix this.

 

Bone stock, turbo? It's best you make a introduction.

 

What type of engine management are you using?

 

Fwiw, I just replaced my bad IACV which used to cause high idle and a dip when coming to a stop, all of that is fixed now.

 

And i happen to have a spare IAC if you need one

 

mines doing this, you just replaced the iacv?

 

Test your solenoid with a meter first to see if it's fried and try running some carb cleaner through it before you replace it. But yes, keeping the original TB and replacing the iacv cured my idle droop and warm idle issues.

 

sorry thanks for your replays its all stock now .except the exhaust and intake . ı have check all the sensors on the engine also the ecu checked no erros in side . its only does this when you stoping the car also I have noticed that idle dip can also occur when at rest and you switch on (or off) the heater fan, air conditioner or even the lights (wherever the electrical power load changes). as low as 400 rpm for 1 or 3 second and back to normal but the engine never stoped for that . ı have search the internet for this problem its says its common problem on miatas. ı know its not a big deal but ı am go for a s1 begi system with xede engine management and trying to fix this problem before setup any suggestions ?

 

yes first ı check the IACV ıts working properly. also go to the auto electronic to be sure ı show the problem he said from the ıacv also he check it s properly working .he check the other things he cant find noting

 

I know this is old but any resolution on this ?

 

yup i am having this problem after i overheated. it still does it

 

ı clean the throttle body and pin the 10 and gdn pins adjust the idle screw and its beter know