Idle question/tailpipe question.......?

[Boost93]

:fp:Ok, Anyone who knows for sure the answer to these,your help is appreciated:D
When driving or pushing gas at a stop,the idle will hang around the 2k rpm range for a good 15 second or so before returning to the 1k mark...Does anyone know what might be causing this,and how to correct it ? just need to know if this is normal on miatas or what?
Second part is about greyish white smoke that comes out of exhaust when at idle after 15min or so of driving? when driven longer and at a stop,no more smoke?.....It comes and goes. should I be concerned or is this also normal on a 93 with 138k on the engine?:shock:
P.S Car runs great and engine is strong...Boost is normal at 10psi.....

[wannafbody]

The high idle might be the valve on the throttle body needing cleaned.

[I<3flippyheadlights]

What are you using for fuel management? That could be the one of the reasons for the high idle.

White smoke means coolent is getting into the combustion chambers. I doubt that is happening to ya. Where are you located? It could be moisture in the tailpipe. My car does the same thing after a decent rain storm.

[Boost93]

On my set up there is a BEGI fuel pressure regulator....But what i mean is,when driving along everything is normal. When coming to a stop and putting into neutral,I let off gas and instead of rpm's returning fast back to 1k. They hover or hang around the 2k mark and 15 seconds or so they finally creep down to 1.5 then 1k again.... As far as the smoke,its random...There is a faint burning smell...As if the exhaust is burning residue or something. Hoping someone here has experienced this and can tell me exactly what the remedy is....

[I<3flippyheadlights]

The idle, I can't help with but it may have something to do with your throttle body. (maybe? Idk) But if you smell something burning it isn't just moisture in the exhaust. What does it smell like to you?

[Boost93]

idk how to explain smell,,,kinda like when u first get a new exhaust etc...The idle happen also in stop and go traffic..will be a 1k and give alittle gas to move up alittle and when i let off gas rpms hover at 1800 to 2000k rpms for 10 good seconds then goes back normal to 1k...this cant be good for gas mileage...its like im holding down a consistent rev with my foot ,but im not...very annoying....

[Opgedronken]

You could try putting a bit more slack on your throttle cable.

[Boost93]

Would cable being to tight,cause those symptoms^^^^^?

[Opgedronken]

Yes, it could be the problem, at least it's an easy fix if it actually is this.
You can test this by pulling up from under your accelerator pedal after it sticks.

[brontosaurus]

I have this issue when my car is cold and thought it was my Megasquirt intially. I'm pretty sure it's just a bad IACV at this point though. With mine, if I let out the clutch quickly while it's stuck at 2k, occasionally it'll settle around idle, but most of the time it just bounces back up.

[Boost93]

Wasnt throttle cable....Maybe timing?....It doesnt surge up and down....

[Boost93]

I was at Pep Boys grabbing some bulbs....Left car running and have been driving about an hour. Guy from the Auto shop portion of the store came up to me and asked if that was my miata? And told me it was smoking,I told him yea it does this sometimes and that its a turbo....He said you have an issue going on for oil to be burning off the exaust like that..He said maybe compressor bearings or something...Now Im concerned,and dont know a reputable mechanic that knows about turboed Miatas in the Raleigh N.C area:fp:

[WASABI]

Can you take a video of the issues? The revs, the smoking? Did you get under your car and look around? There may be visual signs that could further help diagnose the problem.

[I<3flippyheadlights]

If it is the turbo, you can always take it off and ship it out to be rebuilt.

[Boost93]

My friend thinks alittle coolant into the combustion chamber..Is a failing headgasket the only way coolant could be getting in?.....Ive looked under car and in engine bay and nada...

[Boost93]

Anybody?

[I<3flippyheadlights]

Have you ever over heated the car? That would be the only way coolent is getting into the chamber. I really think its the turbo IF you are burning oil.

[RoadsterTech]

Oil can be light blue, coolant is white. You can definately smell the difference. If you want to smell burning oil drop a little on your manifold. Re the idle either your idle control valve could be sticking or your dash pot could be sticking. Causing the higher rpm. Clean both your car will be happier for it.