91 airbox vaccum line question

[FourXFred]

ok, i did a backyard k&n airfilter setup today with some pvc pipe from home depot and a k&n clamp on cone filter. there are 2 vaccum lines attached to the back of the stock airbox, which i just disconnected and plugged. it ran fine for about 1/4 mile, then acted asif it wasnt getting anywhere enough fuel, or only running on like 3 pistons. so i pulled over, and it stalled (might be because IAC valve is gone, but it allways has been, and ive never had any problems with stalling. just rough idle). i started it back up, and again, it ran fine for about 1/4 mile and stalled. it did this all night long, until i put back in the stock airbox and reconnected the vacum lines. anyone have any idea what these vacum lines do? or how i can somehow rig something up so i can get my back yard filter to work? thanks for the info!

 

[biggs85]

I would also like to know exactly what the vacuum lines are for. They go to a lot of different places and I could never figure out what they did. All I know is that you have to cap the lines off with a screw and you should be fine.

 

[FourXFred]

i did that, and thats what caused the problems. i uncapped them afterwards and had the same problems. they go to a sensor in the airbox that appears to be some sort of thermostat or something, but thats just a guess. capping them off wont work.

 

[dejello]

That shouldn't have caused the problem. Not sure if this would have any effect, but did you reset the computer?

 

[jnsnwt]

FourXFred said "ok, i did a backyard k&n airfilter setup today with some pvc pipe from home depot and a k&n clamp on cone filter"

Do you have any pics you could share with the rest of us? I have thought about using PVC to replace all of the stock air tube from the MAF all the way to the metal intake. I have not gotten that far down the "TODO" list yet. If you have aleady invented this setup I'd like to learn from your experience. :smoke:

 

[FourXFred]

i just made a bracket to mount the k&n filter onto the MAF sensor. im still fine tuning the details out, as it makes my truck run like hell. and jello, it definitely made the truck die, as i put the stock box back on and its fine now.

 

[huskyfan23]

The part on the airbox is not a sensor. If you think about it, it doesn't have any electrical wires, just 2 vacuum tubes. It's supposed to help warm up your X quicker but it doesn't matter if you do or don't have it. You might wanna check your MAF, plugging the tubes shouldn't have done anything. When I did my intake I forgot to plug the MAF in and it ran horribly for the few seconds I had it running.

 

[dejello]

Originally posted by FourXFred
i just made a bracket to mount the k&n filter onto the MAF sensor. im still fine tuning the details out, as it makes my truck run like hell. and jello, it definitely made the truck die, as i put the stock box back on and its fine now.

Interesting... One of mine is gone (along with the heat-riser assembly or whatever it is.... And the other one is capped off...

 

[huskyfan23]

Ok I just read your post about putting the factory box back in. The only thing I can think of is the missing IAC valve that you spoke of. I don't really see why that would do anything if it's worked fine before, but maybe your K&N was drawing in lots more air then the stock, which affected the IAC?

 

[Ronin8002]

I think huskyfan23 is probably correct here. The only tube you need to plug is the one that goes back over toward your vacuum tree....it's a very thin one. The other one doesn't go to a vacuum source...if I remember correctly it just fits onto a part of the factory intake that's closer to the grille....you can junk it if you don't plan on going back to the factory setup. You may want to go get a new IAC....that may be the source of your problem. Also..check to see if your MAF filaments are dirty/broken.

You might also try pulling your codes, or resetting your computer.

 

[FourXFred]

ok, so its for the heat or something. im going to assume that it must be a problem with my adapeter that i made, and go back to the depot tomorrow and rig up something a little bit better.

 

[wilson_nick]

Let me know your progress on this, i'm going to be making one out of aluminum and i could use your ideas to help w/my alum. one.

 

[jnsnwt]

Glad to see that I am not the only tight wad out there that won't spend 150 USD for an intake that I can build for myself.

If PVC is not a good choice has anyone found a muffler repair shop that could custom bend some 2.5 or 3 inch pipe to replace the plastic tube ? I have checked locally and the biggest they go is 2.25 inch pipe.

 

[Rhett]

Ok FourX. Make sure you don't have any air leaks around your PVC setup. You may think it's sealed tight but even tiny leaks can cause big problems. If you do have air leaks in the intake stream, you'll get unmetered air into the system, which can throw off the air/fuel mixture and cause rough running and stalling.

 

[FourXFred]

i had to go buy a different piece of pipe to adapt the k&n to the throttle body. if you guys do this, you need a drain for tile floors/ it has about 3 parts on it, a 3 inch inlet, and a piece that bolts onto the back of it. it cost about 7 dollars at the depot. you need to make some custon mods to it using a sawzall, etc etc. ill do a full write up tomorrow, as im stripped on time now. but i found out that my whole problem was that the adapter i used only had a 2 inch outlet, and the MAS wasnt receving proper airflow, and therefore crapping itself. if i was to do this for an on road application (i did this so my air intake will be higher for forging streams) i wouyld suggest putting the air filter in some other place than where the stock box is, as in its current location, it sucks in hot air off the exhaust mainfold, and i actually have about the same power as i did before, if not a little less.

 

[dogfriend]

Originally posted by FourXFred
anyone have any idea what these vacum lines do?

http://www.explorerforum.com/forums/showthread.php?s=&threadid=60204&highlight=heat+stove

http://www.explorerforum.com/forums/showthread.php?s=&threadid=57137&highlight=heat+stove