Remember that air will always travel the path of least resistance. Any air that is not metered by the MAF will not be used in calcualting the AFR for the car. Since the hole is the path of least resistance the air bypasses the MAF. Thus the MAF reads less air than is actually there. The O2 sensor sends it's reading to the ECU and an adjustment is made to compensate for the o2 conditon. The problem is that the car has no idea how much air is comeing in and throws fuel at it to try to stay running.

This is why it is essential to regualarly check for leaks in the system. You might even consider doing a vacuum leak test as well.

I hope that kind of makes sense.

 

The hole is after the MAF though...
Correct me if I am wrong, tHe MAF is connected to the air filter. Air runs from the air filter, through the MAF, then runs through the turbo, and is sent through the intercooler. This hole is after the intercooler, theoretically it should have already been metered... So air is leaking out, and less air is going into the throttle body?

 

That is just the point....since the air is coming in through the hole rather than through the MAF.

Think about this....the filter is restrictive....the turbo is restrictive.....the intercooler is restrictive. Thus, the incoming air tries to find the way in that is the least restrictive. That hole is the least restrictive.

As the car is at idle it is under vacuum. The airwon't blow out the hole, rather it will be sucked in it.

 

Thanks appauld, got it now...lol.

 

will this also cauce the car too run rich in boost because air that is passing the maf is blowing out of the hole?

 

Thanks everyone for the initial help. Figured I would just update the post rather than start a new thread. Seemed problem was a hole in the UICP. Still having issues though, update is in the initial post.

Thanks in advance.

 

RG I have a used Green you might be interested in. PM billy@englishracing for more details

 

Thanks John will do. Any ideas on my new backfiring issue?

 

I'll do some thinking