Jump to content

IGNORED

What the heck is this? *pic included*


sonofzzzap

Recommended Posts

I have been searching and trying to find out what this device is... I have looked through online tech info and my FSM and EFI bible, and I can't figure it out.. what ever it is, its not connected to anything... its the object on the left that has a wire going to it and is a cylinder type shape...

post-7406-14150794755327_thumb.jpg

Link to comment
Share on other sites


Ok, i think I found the name for it finally, BPT valve, the question is, if the end of this is not connected, what goes on within my vaccum system? I have yet to check if it has suction, it is cold and its dark on the eastcoast. I have considerd this also the possible cause of my richness I suffer from...

Link to comment
Share on other sites

I take my description back. In the photo, the cylinder on the left is what I have, and I don't know what it is. Hanes book ( p. 220) has a photo of the egr valve & "vac switching valve," but the switching valve is not what's in the above pic.

Link to comment
Share on other sites

Using the blue connector on the back part of the intake manifold as a reference point. Are you talking about the item at the 9:00 o'clock position that's attached to the manifold with the flat bracket and (3) screws and (3) bolts??

webdawg1

Link to comment
Share on other sites

The flat bracket is bolted to the side on the intake manifold. The tube coming from the bottom of the mystery valve which goes off to the right (in my 280Z) went across the pass. side to to the vacuum solenoids. the isn't any wire going to it, just a hose on either end.

I haven't removed it as yet until I figure out what it does. I thought it was some kind of vacuum port. :ermm:

Link to comment
Share on other sites

I have that on my 78 and have never been able to find out what it is! It is left out of the picture in the FSM. It seems to pull against the linkage under vacuum. Like Tomohawk says, Haynes show a picture of the vacum switching valve which my car and yours does not have. The BPT (Back pressure transducer) valve is the large round one to the left of the EGR valve. Mine is hooked up differently than yours in that vacuum comes directly from the manifold. I always thought it was just part of the California emmisions stuff. If anyone finds out what this actually does, let me know!

post-3797-14150794755587_thumb.jpg

Link to comment
Share on other sites

Steven-

I don't have that 'S' tube in the forground. Instead my 280Z has a vacuum head sticking up with several nipples for vacuum, and a rubber tube coming from the mystery valve. These are on my (fastfrog vacuum hose diagram), which is below. Maybe we can contact some Z-specialist to help us with this? It seems to be the key to several things, including how to get rid of egr valve. Assuming it doesn't help to have it still on there.

The thing that pulls on the throttle linkage is a fast-idle doohickey for cars with a/c.

post-2169-14150794755956_thumb.jpg

Link to comment
Share on other sites

My car has the 'dealer installed' a/c rather than the factory installed setup. It doesn't have some of the things shown in your diagram like the solenoids, the vacuum bottle etc. That 'S' tube is just a vacuum hose. The 'thing that pulls on the throttle linkage' (labeled ? in my picture) is the item that sonofzzap and I are questioning. It doesn't seem to act as part of a fast idle control device (F.I.C.D.) at least not on my car.

Link to comment
Share on other sites

The picture posted on "Fastfrog" appears to be almost exactly what I'm looking at in my FSM for a 75Z. (As far as the magnet valves, vacumn lines...etc...etc are concerned) According to the terminology in the FSM it's called a "Fast Idle Actuator". Only time it should be "On" or "Active" is if you have the A/C turned on. If you pull the wrapping tape off of all the vacumn lines and trace the whole bundle of vacumn lines across to the "Fast Idle Actuator" it should be the "D" connection (Rear solenoid and port facing the passenger side inner fender) on the "Solenoid" (Bracket has it stamped on the bracket as well as to which which port it is) On the "Fast Idle Actuator" side it should be labeled "F". Should be one piece of vacumn line approx. 4-5 feet long +/- a few inches.

webdawg1

Link to comment
Share on other sites

I have the same vacume cylinder on the left hand side of the picture. My car is a california model (1978) with the factory a/c and manual trans. The small vacuum hose goes to a set of solenoids on the passenger side that seem to be hooked up to the a/c system. Im just guessing but I think that the vacuume cylinder in question activates and increases the throttle slightly when the a/c is turned on, since this load at idle causes the engine to drop RPM considerably. On my car however the arm of the vacuume cylinder has been adjusted beyond the range of the throttle linkage so it has to effect that I am aware of.

Hope this helps.

t_andrews

Link to comment
Share on other sites

snip...... On my car however the arm of the vacuume cylinder has been adjusted beyond the range of the throttle linkage so it has to effect that I am aware of.

Hope this helps.

t_andrews

Did you mean to say "no effect that I am aware of?" I only ask because that is how it is set up on my 78.

Link to comment
Share on other sites

  • 7 months later...
The B.P.T. or Bypass Pressure Transducer valve only lets the EGR operate when exhaust backpressure is above a certain P.S.I.

You are correct; that is what the BPT does. However, if you read the thread again, you'll should note that the question is about the item to the left of the BPT in post #1.

Link to comment
Share on other sites

  • 3 months later...
If that is from a california model, then why does my 280Z that is from Georgia have it?

Or did my car come from Cali? this is puzzleing

All California Model 280Z's have a "Floor Temp" sensor light on the panel.

Vicky

Link to comment
Share on other sites

That item is a BPT valve (backpressure transducer). It blocks the vacuum to the EGR valve until there is some pressure in the exhaust system. On some of the early cars with this device they would come unsoldered or detached somehow. Nissan had a recall where they put this brace/bracket to hold the tube against the body. If for some reason you have no tube running up to the transducer from the exhaust or have one of the defective ones have no worries. All that’s happening is that your EGR isn't working. Not good for emissions but unless you have to smog the car or are environmentally conscience your car really won’t care. Some early Fed 280Zs didn't have the EGR and no early car had the BPTD.

The device on the left is the AC idle up. I don't believe I ever saw any Z with a converter that didn't have the floor light. Some of the early 280s had a Catalyst light too. Damn thing came on when a sensor got to a certain temp and tripped a relay. Actually all the early catalytic models had the cat light. Used to have to reset the damn things on brand new cars off the trucks. The guys driving the cars off the boat would start a line of cars and leave em running on the choke while they drove the cars off. On the carburetor cars the fast idle wouldn't shut off by itself in those days and it overheated the cat.

Link to comment
Share on other sites

That item is a BPT valve (back pressure transducer). It blocks the vacuum to the EGR valve until there is some pressure in the exhaust system. On some of the early cars with this device they would come unsoldered or detached somehow. Nissan had a recall where they put this brace/bracket to hold the tube against the body. If for some reason you have no tube running up to the transducer from the exhaust or have one of the defective ones have no worries. All that’s happening is that your EGR isn't working. Not good for emissions but unless you have to smog the car or are environmentally conscience your car really won’t care.

See post #18. The actual question that this thread is based on is answered in post #21.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.