Strange problem (help please?)

[dk05]

Ok, here is the problem. About a month ago I started hearing a strange scraping noise in my (3.4L DOHC) engine, for a while I figured it was just nothing, but then it continued so I took a look under the hood and found the problem. There was a broken vacuum line that I have no idea what it is for. I came here hoping someone could help me out. I have done a very crude job of circling the line on the picture that I tried to attach. What I need to know is, first of all, what is the little device that the line goes to underneath the airbox, also the noise has quieted down alot, but is still there... is there any chance I did some serious damage to my engine by leaving the line broken for about 3 weeks? I appreciate any help that anyone can give me as I am stumped, and would very much so like to get rid of the noise completely.

Thanks a bunch,
Dustin

[LugNut]

that line goes from the upper intake manifold to the transmission
vacuum modulater didnt the tranny shift all wierd when the line was broke?
either way id say no that line leaking couldnt hurt the motor if your
still hearing a vacuum leak you still have a problem somewhere look
at the diagram on the sticker above the radiater and check all the vacuum connections you are using new gaskets for the upper intake
after a test fix right ?

[dk05]

that line goes from the upper intake manifold to the transmission
vacuum modulater didnt the tranny shift all wierd when the line was broke?
either way id say no that line leaking couldnt hurt the motor if your
still hearing a vacuum leak you still have a problem somewhere look
at the diagram on the sticker above the radiater and check all the vacuum connections you are using new gaskets for the upper intake
after a test fix right ?

Thanks for the reply! Not sure what you mean about the new gaskets after a test fix, but yeah they are new gaskets. There was and is no audible vacuum leaks it was actually a very loud grinding noise, like metal to metal scraping. It is still there, just quieted down alot, and now I wonder if I messed up the tranny. Actually I didn't notice any difference in the shifting. I was actually pretty sure that the line did go to the tranny though, and now you confirmed it :-) Well.. anymore help anyone could offer would be great.

~Dk

[WhiteZ34]

I beleive that line connects to the map sensor. There should be two of them that connect right next to each other. One is the metal one which I think is your problem, the other is a very thin flimsy plastic one. It is the one on the right in the picture.

[dk05]

I beleive that line connects to the map sensor. There should be two of them that connect right next to each other. One is the metal one which I think is your problem, the other is a very thin flimsy plastic one. It is the one on the right in the picture.

Thanks for the reply :-) Yeah, that is the one that was broken, but I did fix it and the scraping is still there but only at a certian point on the gas pedal and at a certian speed, although not sure what it is exactly...


~Dk

[WhiteZ34]

i know its a different car, but a friend of mine has a chevy prism that has the same problem. It is the AC compressor on his car. Its been going on for a while now.

[Juglenaut]

I would think leaving that line unattatched for an extended amount of time will effect the whole engine, not only the transmission.

The map controls the shift points into and out of gear from park or neutral to drive or reverse. The vacume diaphragm is regulated by atmosheric pressure as well as ambient temp. Also can cause the TC to act like it is cold and may not shift through gears easy and may also not shift into over drive.

[dk05]

I would think leaving that line unattatched for an extended amount of time will effect the whole engine, not only the transmission.

The map controls the shift points into and out of gear from park or neutral to drive or reverse. The vacume diaphragm is regulated by atmosheric pressure as well as ambient temp. Also can cause the TC to act like it is cold and may not shift through gears easy and may also not shift into over drive.

What kind of effects do you think it could have? The only thing I can notice is the scraping, it is very annoying and I wish I knew what was causing it exactly so I could fix it. As far as the tranny shifting it seems to shift very well yet, no hard or delayed shifting. I noticed it only scrapes while accelerating at low speeds, never while traveling at about 35+ mph. I appreciate all your help on this as I have no idea what could be causing this problem.

~Dk

[dk05]

Just wondering if maybe I could have damaged the transmission vacuum modulator by not having the line hooked up for as long as I did? Or is there something special I need to do when I reinstall the modulator to keep it from leaking? I have a feeling the noise is still coming from the modulator/tranny. I have found out that it only makes the noise when I accelerate around a corner, as strange as that seems. Maybe the modulator is broke and the tranny is having a hard time telling what gear it should be in while cornering? I really have no idea. The noise that is being made is very irritating, and I would sooner not take it in to have it checked out unless it needs to be done. Thanks again for all the info.


~Dk