I have an 03, FX4, 4.6, 4x4, auto, with a Gibson single exhaust, and a Superchips programmer. Oil changed every 2,500 - 3,000 miles, fuel, air, Trans filters, etc all changed well before factory calls for it.. (just trying to say I takecare of my truck)

Now to the problem, I just installed a MAC intake on my truck this weekend. After the install she started to, for lack of better words, miss or backfire. It almost sounded like a potato gun going off with the bulk of the sound coming out the end of the intake.

*It only happens when between 900 - 1300 rpms and ONLY when I was off throttle or just as I would lightly press the throttle. (Happened most when coming to a stop)

First thing I thought of was an air leak as the kit does not come with clamps for the two air hoses that connect just before the throttle body.(PCV and something else) I bought 5 clamps to seal up any possible spots air could be leaking. I also rechecked all the fittings that had hose clamps and cleaned out the throttle body / MAF just incase.

The problem seemed to have gone away as I drove about 100 miles with no problems. Then it started again as I was coming to work this morning. I checked connections as best I could in the parking lot at work. Nothing looked like it backed off and I couldn't hear any sounds that would indicate a leak.

Suggestions on what to do next?

Thanks,
~j


*Pulled DTC with the programmer and only got P1000 and P1635 which both do not help me at all. (OBDII testing not complete & Tire size out of range)

 

Figured it out!

Turns out the rubber grommet around the EGR(?) fitting (the kit came preinstalled with) was collapsed letting in unmetered air. It was really hard to see from the outside but once I tore it down again and looked down the inside of the tube I could see it sticking inside the tube.

Guess I could of pushed it in sliding the hose over the fitting or it could of come that way.

 

Hey FX. I too have a MAC intake on my 2000 F150 5.4L. Although everything went together good, I had a problem where the filter and plastic housing met. Right past the filter and the polished bracket, the blue grommet slid into the plastic intake housing which had the mass air sensor hooked up to it. The only problem was when the engine torqued, this grommet would work itself out and let air bypass the filter and get into the intake, not good. I think I'm just going to buy another clamp to secure things. How do you like yours? The rumble under the hood sounds good to me

 

The rumble is nice and I like the look though I doubt anyone will ever see it but me. I don't show her, just the car.

I'll keep an eye out for the hoses backing off, thanks!

 

i had a mac on my 03=-chromed steel -inside of the tube rusted and the remnants clogged up my maf- learned my lesson-phil

 

...tell me more please.

 

MAC does not= junk. I have a bunch of freinds with MAC set-ups on their trucks, Mustangs, you name it. They hold up to 12-11 second quarter mile runs, are reliable, and havn't caused any of us problems. Maybe you should check your truck or the installation job out before you blame the parts you put on it...