Jump to content

Drilling hole in throttle body to lower iacv duty


Recommended Posts

Hey all,

I am about at my wits end with my idle issues on my car. It will idle with the throttle plate 100% closed and responds to changes (slowly) made with the iacv to increase or decrease rpm. I would like to be able to control idle speed up to ~1500 rpm valve via the iacv, however at 1000 rpm my iacv starts hitting the max clamp value of 95. This is leading me to believe it is not capeable of flowing enough air to sustain idle with my larger than factory camshafts (bc272 cams) the second the ac kicks on, it rad fans the motor dies. I believe this is because the iacv is already at its max clamp value, thus rendering the step up tables that address these issues ineffective.

id like to drill a SMALL hole in the throttle plate to allow more air into the engine at idle, and lower the duty cycle of the iacv. If I’m not way off track, this should make the step up tables work correctly (after the holes been drilled and lowers the duty cycle of the iacv to normal ranges) and allow me to prevent stallling when the ac or fans are kicked on.

I’d also like to point out I’m currently utilizing the ign vs rpm table to help stabilize idle, and it has tremendously helped; however it hasn’t cured the current stalling issue. 

this throttle body is cable driven, and the motor is a Nissan ka24de.  


Thanks in advance for any Insight! 



Link to comment
Share on other sites

it certainly does, i was under the impression it would be better to drill a tiny tiny hole than to crack the throttle body and re program the tps. would i be wrong in this assumption? i didn't want to affect the tps if at all possible since it is referenced by so many tables in the ecu.



These are the current settings, if it’s any help 


Link to comment
Share on other sites

TPS calibration in the Link is extremely easy, I'd adjust the throttle stop before doing something dodgey like drilling a hole in the blade.

Close the idle valve and get the warm idle at the right rpm by adjusting the throttle stop, then you should have enough range of operation with your idle valve to deal with cold start and electrical load idle up/AC

Once that is done you turn engine off, switch the ignition on, do a TPS calibration and save the map

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...