Im in the middle of taking the throttle body off to replace a gasket to fix my idle issue and I had an oddball question. On the inside of the throttle body where the throttle body meets the intake plenum, what are those little holes and what purpose do they serve?

 

Those holes are there to allow the throttle body to get vacuum from the intake so the vacuum ports on the throttle body will work.

 

That makes sense. Some of them dont seem to go anywhere, they're just divots, but the vacuum answer makes sense. Thanks.

 

Sorry to thread resurrect, but I have a question regarding this that I can't seem to find the answer to.

If you look at the two angled rectangular ports at the very top (11 and 1 o'clock, respectively) and you trace the port, they both go to two of the vacuum lines on the very top of the TB. However, if you look at the gasket, it seals them off.

I was just going to RTV since I can't get the gasket locally. Do I need to allow these two vacuum ports access to the main intake air? If not, then what's the point of them even existing? Why not just plug them and rip the tubes out??

Thanks guys!!

 

Most local parts places carry that gasket. The rectangular holes are just part of the casting, there are holes inside the throttle body opening leading to those tubes. They're important, leave them on. Use rtv if you have to, but try and get the gasket.

 

I think those two hose connections have tiny ports in the TB bore, behind the butterfly. They are slightly staggered to give different vacuum signals to the EGR modulator at varying throttle openings.

 

Yep, you guys were right. Upon reinspection I saw the other holes. All buttoned up now, runs great. Thanks!