Bad pair valve mod/vacuum line routing my problem?

[twvette]

I have another long thread about what got me to here so here is a quick summary. My #3 cylinder is not firing properly at low RPMs and get popping, etc. and just runs like crap in general. Figured out if disconnect the Air Intake Pressure sensor all cylinders are well alive. Then realized if I plug the sensor back in and disconnect the vacuum line going to it it is also fine. So something is up with my vacuum line pressure or similar.

I think someone did a bad pair valve mod that is perhaps causing all of this (or not). Here is a schematic and some pictures.

Why would one of the #2 and #3 vacuum lines not be connected and actually have the nipple pulled out from the manifold !!!????

As mentioned above, this pic shows the missing vacuum line and no nipple for it to conenct too next to the vacuum line that is conencted. There would normally be a second brass nipple next too it I assume.

This is what they did at the headers to plug the ports with a screw. Looks like there might be some "epoxy" in there too.



Could someone show me a schematic of how the vacuum lines should be routed in my case (no stock airbox or pair valve)?

Are the vacuum line nipples in the intake manifold replaceable and if so where to get and do they just press in? It doesnt look like they filled the holes with anything.

Should I do one of the more professionally plug kits vendors sell like BDE at the header location instead of the screws or are those screws likely good enough?

 

[twvette]

These are the only vacuum lines I have! it almost seems like I am missing half of the "stuff". Looking at the Service Manual I do not appear to have anything going to a Vacuum Transmission valve, Vacuum Dampner, or a Vacuum Control Solenoid. WTF?

 

[haya2005busa]

see pic i attached:

this is on a 2005 model

this pic is if your looking from front of bike towards rear...so left side is where throttle hookups are.

ok, second nipple going from left to right is what went to PAIR valve.
middle 2 throttle bodies only have 1 nipple each
last throttle body (far right nipple) goes to valve down on right side of bike behind fairing.
if you look in the middle you can see where i have a T valve with 1 disconnected..that line went to module on back of air box.

does that help?

 

[twvette]

Thanks! I think my issue might be that I did not have that T in the middle and that this is where my Air Intake Pressure Sensor should be hooked up rather than on the nipple for #1 shown on the right side. So, the extra nipple on #1 and #4 will be plugged. The theory I have learned now is that this tube is to balance the pressure/vacuum and it see lots of spikes naturally due to each cylinder being in different states. So, if my ECU sees these spikes it wigs out but it needs some idea whats going on for proper fuel injection. Having it in the center should be better balanced but still might need to a restriction or maybe some more volume. Testing this theory out later tonight. Any further input/ideas would be great. I dont have the stock airbox, pair valve, etc. so what I drew in the first pic is all the vacuum lines I have.

In terms of why there are not a second nipple on the #2 and #3 this appears to be just a manufacturing difference between generations of the throttle body and the port is actually not drilled through into the throttle body. If you look at pre '02 they have the nipple but it is just plugged. Each of those nipples see the same pressure in the their individual ports so they basically allow different ways to balance out the pressure and allow other devices to be T'd into the balance loop that is created by chaining them together. Atleast this is how I understand it LOL.

 

[GIXERHP]

The 2 middle cylinders do not have the second nipple.
And yes you are correct, the Map sensor, need to see direct vacuum, from all 4 cylinders, and from the middle!

 

[twvette]

Here is what others are doing with a similar setup as mine that works:

SWEET !!! Just put the theory to test. Just added the T to put the Air Intake Pressure sensor in between #2 and #3 for now and she is MUCH happier. Header temps after a few minutes were 595, 770, 720, and 685.

My #3 is alive !!!!!!

I am hoping after I zip tie up the vacuum lines for better seal will get closer in temps and I know my Power Commander mapping, although not cylinder specific, had a big impact on evening out the temps when I played with that with that before too. Might play around with connecting the fuel pressure regulator to the vacuum line also as if nothing else this will add volume to help dampen the vacuum/pressure in the entire loop but doesnt seem its required. Also considering connecting the extra nipple on #4 with the extra nipple on #1 with the check valve T'd off in the center to perhaps better balance the #1 and #4 and thus also completes a full loop rather than a dead end system (just an idea ... not sure if this is proper). Will add the check valve too to my setup.