High idle 3000rpm on start up, goes to normal after 15 sec

Jaxom_2 · Postby **Jaxom_2** » Fri Feb 12, 2016 5:33 pm

Ok, this is driving me nuts, the engine starts and immediately goes to 3000rpm then settles back to normal idle after 10 - 15 seconds.
I v'e changed the throttle body with IAC the EGR Relay to no avail, I can find no air/vacuum leaks WTF is going on here?
NB2.5 ex turbo Adaptronic, back to factory ready to rotrex, but gotta fix this idle thing.
Any and all help appreciated.
I tried a search oh high +idle + rpm and trolled through countless pages of non related issues if there is a thread oh this subject may I have the link please.
PS signature is a little premature

93_Clubman · Postby **93_Clubman** » Sat Feb 13, 2016 11:47 am

Jaxom_2 wrote:engine starts and immediately goes to 3000rpm then settles back to normal idle after 10 - 15 seconds.
Hot &/or cold?
NB2.5 ex turbo Adaptronic, back to factory ready to rotrex
Given NB8B, are you currently running the Adaptronic &/or OEM ECU?

If you are currently running the OEM ECU, & haven't already, disconnect the battery, press brake pedal a few times, & reconnect battery. Then set the idle as follows: http://www.miata.net/garage/KnowYourCar/S7_Idle.html

Jaxom_2 · Postby **Jaxom_2** » Sat Feb 13, 2016 6:57 pm

It does the same regardless of being hot or cold.
I have the Adaptronic doing the idle - I disconnect the IAC and it does not rev, but I have the Adaptronic settings set to have no influence on the initial idle, if that makes sense - all setting are at zero.

Jaxom_2 · Postby **Jaxom_2** » Sat Feb 13, 2016 7:03 pm

It does the same regardless of being hot or cold.
I have the Adaptronic doing the idle - I disconnect the IAC and it does not rev, but I have the Adaptronic settings set to have no influence on the initial idle, if that makes sense - all setting are at zero.
The car started stalling when pulling up at lights, I changed the Cam position sensor and cleaned the IAC.
I have changed the throttle body/IAC to no avail.
I will try the disconnect of battery and push brake peddle, seems weird to me but hey the idle is even weirder.

Jaxom_2 · Postby **Jaxom_2** » Sat Feb 13, 2016 7:15 pm

The idle screw is turned in completely clockwise, does this mean that the Idle trim is at maximum and I need to back it off? I had turned it to max clockwise in an attempt to stop the car from dying at traffic lights, which it did for a while.

smy0003 · Postby **smy0003** » Sat Feb 13, 2016 8:48 pm

So the Adaptronic is controlling idle? But not initial idle?
What do you mean by that?
My guess would be that the issue was on the ECU side of things, have you tried pulling the adaptronic and running just the stock ECU to see if that fixes the issue?

Jaxom_2 · Postby **Jaxom_2** » Sat Feb 13, 2016 9:15 pm

I set all the settings for the adaptronic idle section to zero, it says doing that has no effect on the idle - ie there is no inputs to the IAC to adjust the idle, I think that is where the idle screw comes in, adjusts the idle speed, the adaptronic settings only influence the dampening the idle hunting, and changes in load on the motor lights being in gear etc.

speed · Postby **speed** » Sun Feb 14, 2016 9:17 am

Re idle screw. Clockwise reduces idle and counter clockwise increases idle.

Sounds to me like an ecu setting that you've missed but I'm not familiar with adaptronics.

Whats the history? Was it perfect before and what has changed since?

How did you test for leaks?

smy0003 · Postby **smy0003** » Sun Feb 14, 2016 9:24 am

So the oem is controlling the iacv, but the adaptronic is doing fuel including art idle?
It could be your fuel table or any one of the numerous enrichments the adaptronic uses. There's more to idle than just the iacv.
What are your post crank enrichment times?

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