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**BobD** · **Air rushing sound from TBI car**

Hi All,

I just bought a 94 Sundance 2.5 TBI. I'm wondering if an air rushing sound could be coming from the 3/4" hose that goes from the valve cover to the air cleaner. The nipple on the air cleaner is broken so the hose just hangs there. I just got the car running last night so I haven't had a lot of time to look at stuff. The sound of the hiss is loud. Could the hose being off make this sound? I've been driving turbos too long. I don't know/remember much about anything else.

XxhorizonxX · 12-12-2006, 08:52 AM

that should be just the breather hose......... sounds to me like you got a big vacuum leak somewhere............... how does the car run? ......does it idle funny or anything?

88_Pacifica · 12-12-2006, 09:48 AM

That is the vacuum hose that controls the "thermac unit"(GM terminology... sorry) that is what regulates the temperature for hot air/ cold air induction that is used for "warm up" typically. I used to have a 2.2 horizon that had this and when it gets really hot or really cold it will dictate the function of the system. It goes to the temp sensor which is affected by a thermatically sensitive piece of metal inside the plastic sensor. It is "univerally" the same concept in all vehicles, but was much more prominent in the carb cars and early TBI units... Here's a link explaining it... Hope this helps...

http://tech.oldsgmail.com/emis_THERMAC.php

HotRodDodge · 12-12-2006, 11:58 AM

The TBI cars do make a loud sucking sound and its even louder if you have the air cleaner off. Might be normal if it seems to be running fine.

**BobD** · 12-12-2006, 05:43 PM

Quote:

The TBI cars do make a loud sucking sound and its even louder if you have the air cleaner off. Might be normal if it seems to be running fine.

The car seams to run fine. That must be what it is then. The hose is so big, the sound must be coming out the hole which is almost like having the air cleaner off. Thanks. I'll just pick up another air cleaner next time I'm at a salvage yard. This TBI car opens up a whole new type of stuff to search for in yards.

I bet I can even find stuff now days.