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What is the function of the black 6 sided knob w/ vacuum lines connected to it on my 1994 toyota

The knob is on top of engine w/ spring under it,seems to have no effect on engine when turned

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  • page hardy Jan 04, 2014

    it is on the rt. side of the plenium chamber when facing the truck, the egine is a 2.4 litre 4 cyl.



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I have been thinking about your request over and over (lol). First I wondered if you might be describing the Throttle Body, but there isn't a six sided knob. So I looked again and I believe you are referring to the valve cover. The valve cover is made of aluminum, rectangular, and is on top of the motor. The oil fill-cap is a six sided knob (no spring underneath but could have in inside it to let it click), and there are four spark-plug wires coming out of the valve cover that you may think are vacuum lines. Please write me back and let me know if this is in fact, what you were describing. If not, try describing other parts that are next to this part (in question). Good luck.

Posted on Mar 13, 2014

Testimonial: "no, this is a black knob about size of a dime,vaccuum lines going to it, seems to have no effect on idle 22-re engine 94 toyota base pickup 4 cyl."

  • Larry Blais
    Larry Blais Mar 15, 2014

    I do apoligize but I can not help you at this time. The description that you provided me just isn't enough. If you were able to help me narrow down this serch it would help. The vacuum diagram is posted under the hood. If the diagram has been removed, you can google it and view it that way. The engine comartment houses many parts that are a part of the vacuum ciruit. I have looked over images of different 1994 toyota trucks with a 2.2L. I don't see anything that resembles a six sided knob (the size of a dime) with vacuum lines and doesn't affect the engine while its running at an idle. You may try viewing a vacuum diagram on your own or write back with a detailed description of the suspected items location. As you can tell, there are vacuum lines all over the place. Please narrow down the area that you are describing. You may be talking about the EGR valve vacuum modulator valve but I am not sure at this time. Once again, I apoligize. I pride myself in helping others with their questions but I am very dependent on specifics and details. If anything else arises and you would like to give me another try, I would be more than happy to give it another try, good luck.



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SOURCE: I need a vacuum line diagram fo a 1996 Chevy

Sorry I don't have the diagram, but I do have a diagram of the engine and component locations. Your vacuum system is fairly simple. You have a MAP sensor attached to the air cleaner. I have pasted a picture below. It has one electrical connector and one vacuum hose that goes to the intake manifold or the throttle body.
Behind the right headlight is your evap canister. This will have a hose or line running to the fuel tank. Then it will have another hose going to the purge valve. The purge valve should be close by and it has a connector plus another hose that goes to the intake manifold.
Then you have the PCV hose that goes from the PCV valve in the valve cover to the air cleaner or intake manifold. I think yours just has a hose from the air cleaner and the rest is internal.
There is one more vacuum hose, and that is the bog one that goes from the intake manifold (or throttle body--looks to me like there are a couple of vacuum ports on the back side of the throttle body, and there may be a "T" on one of the hoses) to the brake booster. It this one was off, the engine would not run, as the vacuum draw is large. Please let me know if you cannot figure it out from these instructions and provide a picture, if you can.

MAP sensor:

purge valve:


Posted on Oct 30, 2011

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