I have a 2002 with a 4.6L that I recently installed a MAC Performance CAI on. The performance increase is notibly better, however, I now have odd noise at idle. When the truck is idling, pumps kicking on/off, or decelerating it makes a hollow kind of popping noise and the idle flucuates down and then up. Sometimes its a few noises and stops. Other times its many and if left to continue it almost stalls the truck. I can reproduce the noise by lighting revving the engine but not every rev. Under acceleration it pulls hard and sounds great. I have checked all lines and fittings and cannot find a leak. I've been reading alot about O2 sensors, MAF dirty, vacuum leaks, etc. Replacing the stock intake eliminates the problem completely as quickly as it started.

Any suggestions greatly appreciated. The cheapest ones first.

 

did you disconnect the battery for a while to reset the computer after the install?

 

It was actually disconnected for about 2 hours as I had to stop when dinner bell rang. I have heard alot of debate over which side to disconnect though and I did positive because my negative side bolt head was stripped and I was short a set of plyers at the time. I really didn't think it mattered but I'm up for trying anything at this point.

 

when I installed my AF1 back in the day, I never disconnected the battery and never had any problems.

 

my aem brute force said to only disconnect the negative i dont know why that is...