dwhite645

Ok, so I installed my Mac off road H last night, DID NOT get the MIL eliminators, yet my check engine light does not come on. I thought on the 96+ mustangs that if you installed an off road mid pipe, it would come on no matter what, unless you bought the MIL's. It's an '01 4.6. Any suggestions? Oh, I also hear a little bit of a hiss while getting going faster. I thought it was a leak, and re-impacted everything on and felt around. No leak. To test the leak factor even more thouroughly, while driving at 20 mph, I had my right foot floored on the gas while holding the brake with my left to cause the engine to push harder. No sound of a leak that way. It didn't do this with the factory H, so I have no idea. Any suggestions?

Dan04COBRA

On any OBD controlled Mustang with an off-road x/h pipe you WILL need MIL Eliminators.

As for the leak, there is a tricky O-ring that is only on one side of your x/h pipe nearest your headers/manifolds. This is where everyone experiences a hiss & leaking problem.

04mustang

ive got a x pipe and have a hissing noise to but it only does it between idle and about 2000 rpms and goes away. you cant hear it if you put it in neutral and rev it . i dont understand why you can hear it only at these times. i also put back on the gasket that was on the passanger side. the gasket was fine and nothing was damaged. could it still be leaking from there cause those bolts are as tight as they can go. or could it be something else?

dwhite645

Dan02GT: what exactly does the MIL eliminator do other than turn off the check engine light? If that's all it does, then I don't need one since the lights not on. Does it adjust mixture or anything else?

04mustang: That's exactly what I'm talking about. Mine does it between 1200-1800 rpm's approx, and only under a little load. It won't hiss in neutral on mine either. I don't think it's a leak, since I used a new gasket that came with the H pipe, and we impacted it on all over. I can't feel any or hear any while I'm under it. Not sure what it is, but it's definately not a leak.

04mustang

hey if you figure it out you better tell me what it is cause it is has me fooled what it is and where its coming from. its hard to fix something if you cant hear when you are under the car. ill let you know first thing if i find out what it is.

Dan04COBRA

They will come on. It has taken up to a week of driving for the light to come on. It pulls timing and adds fuel when the light comes on..

USAMuscle

Yep, I can tell you from personal experience it took a few days after I put my off-road X-pipe on for the light to come on, and after it did, the car drove like a dog. You will for sure need them, so plan on getting them ASAP or you're going to dislike your ride.

dwhite645

Well, I knew it was too good to be true. Driving into work this morning and the light came on. Dammit! It still drives the same though, can't tell any difference. I guess I'll have to buy the MIL elims. to get rid of the light.

04mustang

Did u find out where the swooshing noise is coming from?[:-]

dwhite645

Ok, so far so good. After realizing that I can probably make my own MIL elims, I did some checking with a few electrical engineers I know. Yeah, they weren't much help. I used somebody else's schematic and it consists of a PC board, a capacitor, resistor, small jumper wire, and 2 PCB term strips. Multiply each by 2 and you have your pair of MIL eliminators. I also wrapped each one with a section of bike inner tube and electrical tape to prevent water and heat damage.
Anyway, here's how it went: I get home from radioshack, assemble my MIL elims, jack up the car...again... and go to town. After some mild cursing, I had them installed. I jump in, start her up, and the 'service engine soon' light is still on. Son of a... So, I lower her off the stands, take it for a spin to see if there was any difference. None. While driving along, some 17 year old turds in a mullet mobile (89 IROC) pull up along side and I guess they think I want to race. I'm older and not into that anymore. Anyway, cruising along (mullet mobile not far behind) some dingleberry 16 year old girl in a sunfire convert is riding my ***. I don't like that. She was so close, I couldn't see her headlights. I had enough and dumped into second, back spinning tires and all, and that little sunfire sure did a good nose dive from the hard braking. I forgot about the mullet mobile. They must have thought I was showing off since they yelled some expletives while driving by. Oh well, look what they're driving. I didn't know any of those were still on the road! The sunfire was back right up my *** after not learning it's lesson, so this time, I braked down to 20 until she got mad and tried to pass. She didn't accomplish the objective. Well, After being thoroughly disgusted, I drive back home with hissing sound, and 'service engine soon' light staring at me. I get out and stare at it for a minute, and I swear to god, I think: dammit, I wonder what I could get for a trade for a new Mach 1, this damn thing. So I go in and start reading posts here about the light coming on. I originally thought that the computer would have to be reset, but I wasn't sure. I read on, and learned that I could just unhook the battery for about 10 mins. I did this, and while staring at the engine bay, still cursing and being disgusted, I noticed that a big vacuum line was off. WTF? It was coming from the driver side valve cover, and goes to the intake tube (from the air filter). It leads right in front of the throttle body and spans across the engine to the valve cover. I thought, how in the hell did this come off? I thought back, and never had it off for any reason. I put it back, and tried to pull it out again to see if it just fell out by itself. No way, it took some force to get it off, and it's approx 5/8" in diameter. A big sucker. So I'm feeling better that it might be the hissing sound I can hear. After a while, I hook up the battery, and go for yet another drive at 3am. My neighbors must love it. So I'm driving, and no 'service engine soon' light or any hissing sound! I fixed it! I take it out on the highway, slow down to 55 and drop it in 3rd. Holy crap! I shot up to 70, in no time, in 3rd, with only 3.27's! So I later came to a red and got on it from a 10 mph roll in 1st. Now I jumped to 75 in an effortless 6 seconds approximately with the new H and borlas screaming! I was off like a prom dress. It feels like a whole new car! Damn I thought, my butt got planted to the seat pretty good. I'd just like to know how long that line was unhooked, and who did it. I'll see what happens in the next few days with the home made MIL elims. It took a day and a half for the engine light to come on after the H pipe install, we'll see if it stays off for good. Just saved myself $60 if it does. If it works, I came make them for people pretty cheap. Here are some pics...

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