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#1
Maniac motorsports12

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When the throttle is moved just past idle and held there, the RPM surges radically, from all most stalling to back to where you are holding the throttle.  It makes it very difficult getting out of the pits.  I tried putting in a new ECU and no change.  I tried shutting the car off and re-starting, and sometimes that is a temporary fix, but not all the time.  At higher RPM it does not do it, just that 1k to 2k range.  If I disconnect the electrical connector on the side of the throttle body it stops but then the idle is way to high.  Any help would be appreciated.  No one locally has any idea.



#2
David S.

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I'm still new to the Miatas but on all of the Hondas I have owned if they got low on coolant they would act like that. Check the coolant and make sure that it is properly bled. Good luck!

#3
Jim Drago

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You have a dirty or bad idle air control motor.  You can try remove the the throttle body and clean it out with carb cleaner.  If that doesn't work, you need a throttle body. I think I know a guy who sells them :)  This is very common on 9 Miatas. Changed two this weekend


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#4
Michael Novak

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TPS?
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#5
Cy Peake

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You had recent track time where and when?


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#6
svvs

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    do they sell spec training wheels yet?

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Down here things are clearing up Cy.  NJMP opened up the other day.


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#7
ccrowel5

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X



#8
Jim Drago

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I just had a similar problem on my car. I chased it all around. Idle air control could be it and it could also be TPS. Strangely enough on my car it was a bad front O2 sensor which also caused the car to run extremely rich above 6k rpm. I also took my IAC off and cleaned it. Car runs great now.

 

 

Not to contradict... But the 02 did not cause the car to run rich, most likely a coincidence.  I have never seen anything but the idle air control motor cause the surging. 


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#9
Qik Nip

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Not to contradict... But the 02 did not cause the car to run rich, most likely a coincidence.  I have never seen anything but the idle air control motor cause the surging. 

 

Agree with Jim. Also, on 1.6 (at least) the O2 sensor is out of the loop at WOT.

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#10
Stix37867

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^ Two completely different styles of ecu's. 99 and 96-97 are OBD2 which use wideband O2 sensors whereas 1.6 uses narrowband, which like you stated is useless at WOT. The OBD2 systems use the wideband O2 sensor to constantly tweak the a/f mixture as desired/programmed in the ecu.

 

Still Jim is right about it being a coincidence. A bad O2 sensor would affect a/f more than just above 6k rpm.


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#11
HoneyBadger - BrianW

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^ Two completely different styles of ecu's. 99 and 96-97 are OBD2 which use wideband O2 sensors whereas 1.6 uses narrowband, which like you stated is useless at WOT. The OBD2 systems use the wideband O2 sensor to constantly tweak the a/f mixture as desired/programmed in the ecu.

Still Jim is right about it being a coincidence. A bad O2 sensor would affect a/f more than just above 6k rpm.


I am pretty sure the 99 O2 is not a wide band.
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#12
Stix37867

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Sure is. NTK 22502 is the replacement part# for both generations minus the 1.6's. Both are 4-wire non-heated sensors.


-David Schroeder

#13
HoneyBadger - BrianW

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Sure is. NTK 22502 is the replacement part# for both generations minus the 1.6's. Both are 4-wire non-heated sensors.

The voltage output from that part number is 0-1v, which indicates a narrow band O2 sensor.


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