Drill Hole In Throttle Body Plate To Fix Surge?

[mustang90]

I picked my car up from the dyno shop a week ago. I had a 70mm mac throttle body on there but replaced it with a 75mm accufab unit. I set my tps at .98 volts by probing the green wire and black wire with ignition off. My car is supercharged but anyways the idle will not set still, it will surge up and down.
I did notice that the shop who dynoed the car drilled a little hole in the throttle plate and prior to my install it was perfect. Should I just drill a hole in the accufab plate?

 

[10HoleLX]

You said you set the tps with ignition off.
Should set with ignition with key set to "on" position but with engine off.
I wouldn't drill a hole in the throttle blade.
I have a 65mm Accufab TB with no hole drilled.
Go to a Ford dealer and buy an idle adjuster plate that goes between the Idle bypass valve and the throttle body ($20). That should fix your problem.
Also try setting your TPS to the lowest setting, that worked for me in conjunction with the idle adjuster plate.
Good luck.
DM

 

[blk92stangg]

Surging like that is also indicative of a bad IAB. How did you reset the idle after you changed throttle bodies? If the throttle plate is fully closed at idle, a less than perfectly clean and well working IAB may not be able to supply a steady supply of air to keep the car running. My unproven theory on bad idle is that many times a badly adjusted throttle plate, coupled with a cruddy iab, will cause crappy idle.

 

[mustang90]

I know that the IAB is good beacuse everything on the car is new. I think I will take the car back to the dyno shop and have them readjust it. I dont want to screw anything up. Anyways its on gonna cost me 50 bucks.

 

[1Slow5oh]

Id presonally mess with it myself before I blew 50 bucks. Check all of your vaccum(sp)? lines.

You could also call the shop and ask if they have any solutions.

Good luck