Hi guys. I know this gets talked about a lot but search is retrieving very few threads that actually focus on this and they aren't answering my questions. However, future searchers should be able to find this one easily.


Anyhow, I found this diagram on PFF. While this looks good and all it appears overly simplified from how my 3800 was originally set up. In addition, if I did do a routing like this I would have a lot of unused vaccuum ports. In any case, I'm just looking for some general guidance on how to approach this. Do most people block off a lot of these vacuum lines and change the routing dramatically or was my initial engine setup just strange? Thanks in advance



For example...

1) My throttle body has two ports, one of which was t'd off in two opposite directions. The diagram only shows one line coming off this. I imagine that these extra lines don't need to be used but I would like to know what they are originally for especially since they aren't in the diagram above



2) The unit which feeds the brake booster has three ports in total...the diagram only shows two. While one did run to the bbv, another line ran off somewhere (I'm not sure where)

3) My boost bypass solenoid has three ports in total, one which is connected to the actuator...one I'm not sure about...and one which is connected to yet another tri-port unit on the supercharger (I don't even see this unit in the diagram). Here's a pic since I don't really know how to describe it better.



4) The "supercharger assembly" never ran to the bbv on my engine initially. It only ran off somwhere towards the MAP sensors
Anyhow, I have more but I'm sure you get the idea. Thanks in advance for the help and comments.

You have a 97 blower in your pictures, which is much different than the 98 style routing you have in that picture.

As far as things go, you can run your routing however you wish, you just need to know what needs "boost vacuum" and what needs "no boost vacuum". On a 97, your "tree" thing is boost vacuum, as well as the port under the blower. The non boost parts are the big 3/8 T fitting on the top of the blower, and the port on your throttle body.

Most people will block off all but 1 port on the big T on the blower, and run that to the BBV, run the brake booster to the EVAP line on the throttle body, and run boost reference to the fuel rail, MAP sensor.

I personally would leave the BBV in manual mode, which just uses a non boost vacuum source to work... you just connect the top port to the top of the blower and leave the bottom side open to fresh air. Remove the solenoid, and all the lines associated.

Thanks DH, plus for the help

quote Originally posted by darkhorizon: You have a 97 blower in your pictures, which is much different than the 98 style routing you have in that picture.

Ah...I was suspecting as much even though my source for the engine claimed it was from a 98. Hopefully this doesn't back to haunt me anywhere else on this swap.

quote Originally posted by darkhorizon: As far as things go, you can run your routing however you wish, you just need to know what needs "boost vacuum" and what needs "no boost vacuum". On a 97, your "tree" thing is boost vacuum, as well as the port under the blower. The non boost parts are the big 3/8 T fitting on the top of the blower, and the port on your throttle body. Most people will block off all but 1 port on the big T on the blower, and run that to the BBV, run the brake booster to the EVAP line on the throttle body, and run boost reference to the fuel rail, MAP sensor.

That sounds like that would clean things up quite a bit...

Alright, so what needs "boost vacuum" and what needs "no boost vacuum"?

"Boost vacuum"
-BBV solenoid
-Fuel Pressure Regulator
-MAP sensors

"No Boost Vacuum"
-Brakes
-BBV actuator

What else am I missing here?

And what about these two guys?

quote Originally posted by darkhorizon: I personally would leave the BBV in manual mode, which just uses a non boost vacuum source to work... you just connect the top port to the top of the blower and leave the bottom side open to fresh air. Remove the solenoid, and all the lines associated.

Interesting idea. Is this a popular? How much of a role does the ECM play with the solenoid?

Here's a couple more pics for ya.
Last one is how I ran my setup with the Evap deleted.

Nice! Thanks (+)

That looks like that would clean things up quite a bit. It might help even more to run the brake booster off of the throttle body if possible.

What did you do for EVAP out of curiousity or did you just leave it out altogether? Have you had any issues with it if you did?

quote Originally posted by GraterFang: What did you do for EVAP out of curiousity or did you just leave it out altogether? Have you had any issues with it if you did?

It's all deleted. No emissions in OK. I don't know if there are flags concerning EVAP that get changed when the PCM is re-flashed but I think there are and Ryan at Sinister took care of them. No issues. EGR is gone too.

quote Originally posted by GraterFang: Oh yeah..does anybody have any "clean" looking ways of plugging off these vacuum ports? In the past I've always used a bolt or something but it's pretty ghetto looking

Up at Autozone (or most auto parts stores) in the help section they have some nice rubber vacuum caps in different sizes. Sometimes they are next to the vacuum tee's and other fittings.

I spun the big plug on the top of the supercharger 180 degrees and then capped one port and used the other two for brakes and BBV.

[This message has been edited by Bubbajuju (edited 05-23-2009).]

Yes, the rubber vacuum caps are a nice fix. With many 97 s/c's I come across, I typically remove that entire tree & plug the hole with a 3/8" NPT plug. This is probably not an option for you, since it's on the car, though.

x2 on deleting EVAP, and the BBV solenoid as well, if you get the DTC shut off for it.

I make a point to do very simplified vacuum routings (clean looking appearance, and 100x easier to hunt for leaks). Everything you're connecting can be run in as short of a path as possible, and all hidden on the back (front) side of the s/c. With a 98+ sc/lim and using a TB adapter plate it's a bit easier, but even with yours, you should be able to come up with something clean and unique.

- Dave

------------------
'98 Daytona GTP - MP112 & ZZP I/C (warming up before a RWD 3800SC build)
back in '06 - 333.5whpSAE - 12.73 @ 111mph (street tires) GenV, XP, 9.4:1, stock heads, non-I/C
Admin of CNY3800
http://geocities.com/dezldave961/

quote Originally posted by dezldave961: Yes, the rubber vacuum caps are a nice fix. With many 97 s/c's I come across, I typically remove that entire tree & plug the hole with a 3/8" NPT plug. This is probably not an option for you, since it's on the car, though. x2 on deleting EVAP, and the BBV solenoid as well, if you get the DTC shut off for it. I make a point to do very simplified vacuum routings (clean looking appearance, and 100x easier to hunt for leaks). Everything you're connecting can be run in as short of a path as possible, and all hidden on the back (front) side of the s/c. With a 98+ sc/lim and using a TB adapter plate it's a bit easier, but even with yours, you should be able to come up with something clean and unique. - Dave

Nice, thanks to both of you for the help.

I would probably delete the BBV solenoid but currently my ECM is likely setup for it (there are DTC's for the BBV solenoid, right?) and it isn't too much extra stuff to work in. However, are there any supposed benefits to running without it other than simplicity?

Also, I would like to try and also make an effort to keep the EVAP but I would really like to try and simplify the setup. Can I simply just run a vacuum line to a charcoal canister with an electric purge or do I need the extra stuff (switch and purge valve) that came with the 3800?

[This message has been edited by GraterFang (edited 05-24-2009).]

If you've ever noticed how often newer GM vehicles set DTC's for EVAP systems, you can see how picky they are about all components involved. The Fiero fuel system doesn't have all of the complex items involved to let the pcm monitor, diagnose, and utilize EVAP. It's just best to leave it off instead of adding 4-5 difficult-to-include items, just to use the 2 easy-to-keep items.

The BBV's solenoid is only for pcm overriding of the BBV's natural functioning, for various torque management modes, reverse, and speed/etc. limiters. It can also cause people to wonder why they're only getting the default ~4psi if it's improperly functioning. On 90% of the 3800 cars I modify, this item is unbolted from the BBV and not used. You'll need to have DTC P0243/P1646 de-activated, depending on year/model of pcm file.


(on a top-swapped '04 Impala... hence all the extra wiring/vac lines on the front of the engine)

- Dave

[This message has been edited by dezldave961 (edited 05-25-2009).]

bbv's can be extremely handy for launch control.