Hey folks I'm Kevin from Denver... new to this site! It's nice to meet you all... I drive a 1991 Ford E250 extended with a 5.8 auto cargo for my carpet cleaning business and I love it.

I was replacing my idle air control valve today to fix my fluctuating idle and that did fix my problem but I noticed something that seemed odd to me. On the butterfly valves in the throttle body there is a small maybe 1/8 inch hole drilled into each butterfly valve. I've never seen that before - is that normal? The holes seem to be drilled into the exact same location on each butterfly valve...

I read that a way to check if your butterfly valves are shut properly is to unplug the idle air control valve while the engine is running and it should die, but when I unplugged mine it stayed running, only at a much lower rpm. There was a hissing sound coming from the holes in the butterfly valve and when I plugged them up with my fingers the engine died.

The engine runs fine right now and idles properly. I don't have a tach on this truck but I don't think the holes are messing up the idle. With the new iacv connected, the engine runs at the same rpm when I cover up the holes with my fingers...it just takes a second to compensate.

Seems weird...should they be plugged up? Are they taking away from my engine braking? Thanks for any input...I've just never seen holes drilled into the butterfly valve.

 

Cross posting the same message in different forums is annoying. Your answer is here:

https://www.ford-trucks.com/forums/1...l#post12296580