Thumbnail on porting a throttle body
I have no tip in or adaptive issues with my ported throttle body.
The throttle blades must be marked (indexed) on disassembly to get them in the exact stock position when you reassemble the butterflys to the shaft, and to the throttle bores. A small scribe with a very sharp point works well, for marking the blades and housing.
Remove the TPS.
The butterfly shaft threads that protrude through the shaft must be ground flush with the throttle shaft to prevent breakage. They are swedged in and even after grinding you will need to use lubricant, (Zep 45, Triflow, penetrant) to get them out. Some of them might not come out easily even after grinding and lubricating. Screw them out and in to get them to release. Alternate going back and forth between the screws to give them a chance to cool down, they will get hot. Work slowly so as not to break a screw. Keep the screws in order so you can reinstall them back in the same hole they came out of.
The shaft positioning is critical with regards to lateral movement to keep the butterflys from binding, and have correct air flow at idle.
If you do not want to remove the bearings from the housing mask them off carefully so no debris can get into the bearing itself.
Do not touch the areas of the throttle body bore where the butterflys ride.
Measure the TPS pin out resistance before dissassembly so it can be reset to the factory calibration. Prefferably measure the actual output voltage of the TPS wiper at idle. this is more accurate than measuring resistance.
After porting, blending and polishing, clean all the metal parts with brake clean, very well. Blowing out everything but the TPS with high pressure compressed air. Making sure that the threads on the screws and the shaft are cleaned of all dirt and oily residue. Do not get cleaner on the TPS, or O rings.
Reinstall the shaft, install the butterflys but do not tighten yet, just snug the screws down loosly. Carefully align your scribe marks between the butterflys and the throttle body housing. Once you have the butterflys in position (this will take some time to align correctly). Make sure that there is no binding between the butterfllys and the housing. Tighten the butterfly screws to final torque. Recheck the butterflys and housing for any binding or misallignment. Remove the screws one at a time and apply Blue thread locker to the threads of each screw. Reinstall and tighten the screw with the loctite and go to the next screw, repeating the process untill all screws are tightned with thread locker. Check for proper alignment of the butterflys to housing once mere.
Reinstall the TPS and check for resistance or voltage.