4.6 and vacuum issues

[Chuck Norris]

Ever since I bought the TC it's made a slight hissing noise under the hood, gotten poor gas mileage, and had a somewhat shakey idle on occassion. I put in a new air filter last week, and much to my suprise, the gas mileage DEcreased and it ran less powerfully. Today it started to surge terribly, so bad I stopped the car and popped the hood. I then noticed a pronounced hiss, but coming from where? Well, right before what I guess is the intake manifold, there is on my car a big plastic "thing" that says OHC V8, then proceeding towards the front of the car, an air tube and then the air box. Well, that plastic contraption with V8 printed on it wasn't attatched to the intake manifold correctly, and it was hissing. When I loosened the hose-type clamp and attempted to reassemble the peices, the idle really dropped. Then when I fit them together, it returned to normal. I hopped in the car and put it in drive, and it was as smooth as silk! But the plastic V8 thing doesn't attatch well and has a bad crack in it, so I think I will be looking for a replacement part. But the car is running better than it ever did. I thank in part for this discovery P71Towny, who informed me of some maintanance issues I may want to chec out to raise my gas mileage. I had actually purchased a new PCV valve (at Townys behest) and in locating the existing unit, had messed with some vacuum lines, so when the car messed up I thought "vacuum line, accidently loosened one." Then I found the real culprit. Gas mileage is now looking more like 25 mpg or so instead of the 19-20.5 I had been getting. Thanks Towny!

[85crownHPP]

sounds like the air tube going into the throttle body - if thats cracked and letting air it, it will run poorly. That is what they mean when they say "unmetered air" becuase it is slippin in past the MAF sensor undetected, so the computer doent know you are trying to go faster...

[Chuck Norris]

sounds like the air tube going into the throttle body - if thats cracked and letting air it, it will run poorly. That is what they mean when they say "unmetered air" becuase it is slippin in past the MAF sensor undetected, so the computer doent know you are trying to go faster...

Well, unfortunatly, whatever it was I did didn't last. It's chugging again, not sure why, may be because there is a larger line diconnected under the hood. It also has vacuum (it runs from the air tube to some doohicky on the driver-side valve cover that looks like a pcv but isn't.) The autoparts store was short on hoses so I couldn't replace it, but they'll have it in tomorrow.. Also, I had to force an undersized tube onto the new pvc because they didn't have that either. Thats why living in the boonies sucks. But I temporarily had better gas mileage and a smoother ride, and when I get the proper lines back on I will have it again. I hope.

[85crownHPP]

But the plastic V8 thing doesn't attatch well and has a bad crack in it, so I think I will be looking for a replacement part.

I bet the crack is still a problem. replace this thing!!!

say no to crack!!!!

[Chuck Norris]

I bet the crack is still a problem. replace this thing!!!

say no to crack!!!!

Yeah, I'm going to go to the parts yard and pick up another one. I had it going great, but then it started chugging. I decided just stop at Autozone, get the new lines and whatnot (like I mentioned, I had to settle for the wrong size, but they GAVE them to me.) I detatched that ait contraption and reattched it, messed with some of the lines, replaced the soft rubber lines that run to the pcv. When I started her up it was chuggin still. Messed with lines more and it straightened up. Disconnected the line that runs to the pcv-looking thing and BAM! instantly running perfect. I thought maybe it wasn't getting enough flow through that air contraption, so i go inside and buy a minifilter and stick it right on the line. Car dies immediatly. But when I attached it to the line, I trimmed it doen to short to reattach it properly so now there is no line there, and too small of a line on the actual pcv that I trimmed the middle out of to fit. They will have the proper parts in tomorrow from a sister store I think, so I will go get the right stuff, and replace the "air contraption (air tube you called it) next week hopefully. Before it started chugging again, I was geting great gas mileage, and I'd like that to be a permanent thing. So here's to new rubber!
It's so hard to tell whats wrong with cars sometimes. I wish I had a pile of test equipment sometimes. But I know it's vacuum related, so at least I know where to start.

[p71towny]

Dude, you can have my 4.6 air intake since I made a cold air setup for my car. Its yours for free, just pay shipping. Its one of the things I was gonna get rid of at scottfest. Also, behind your intake you will see a tan colored tee with vacuum lines running too it. It goes to your brake booster as well. Check that for cracks as those are prone to it. Hope this helps.

[Chuck Norris]

I'll check that out, thanks. I managed to wrap the unit I have with "wrap tape" and seal the crack, but I'll take you up on your offer when I get back from Louisville, that is, unless you want to meet up. I'll be there next week from Monday till Friday but I will be on the run most of the time. If not, I'll just have you ship it. Give me an approximate weight so I know how much shipping will be please. And thank you VERY much!