potato

My car seemed to run okay until I tried to up the boost on my new controller. after WOT and hitting about 10psi it starts idling horribly when im slowing down and drops to about 100 rpms and bounces back up to about 1100 and down to ~100. at that point it seems like i have no vacuum and the car idles horribly all the way back home. In researching the issue to see what others say I think my vacuum lines may just be wrong. heres my current setup



after doing some searching and reading, I have come up with the following to better run (i hope) my vacuum lines. left vacuum above throttle body to fpr tee'd to boost gauge. left vacuum above throttle body to bov. tap into hot pipe to run a line to boost controller to wastegate



if my current setup is fine, could my vacuum issues be from different size vacuum lines when it tee's off to the BOV and boost contoller/wastegate? before the boost controller it was run this same way, but with bigger vacuum line (ive replaced it with what came with my hallman boost controller).

if the new setup would be optimal then I just need to know what size vacuum line I will need for all pieces

any input is appreciated. if you want to draw your own layout, here is the original http://i.imgur.com/E65wKKp.jpg

derass

The first photo is ok, but the second photo is ideal. Simply because the wastegate will not see vacuum as they are not designed for that. However, neither are so terrible that they would cause the engine to run poorly. If the idle issue did not exist before adding the MBC, it would be safe to assume the addition of different sized lines and tees may be the cause.

Thinking about it further, if there are no vacuum leaks, the only other thing that could be the cause is the FPR, but you did not do anything to those lines.

If you don't want to weld a nipple to the hotpipe, you can use on of these to get your wastegate signal:
http://www.atpturbo.com/mm5/merchant...egory_Code=BCS

potato

no new tee's were added, just different vacuum line size for the mbc. i did recently replace the FPR and boost gauge because my old one was bad however i hooked it back up the same way and used the same lines/locations. if my second design is ideal, ill redo it and use the quick tap like you suggested for the mbc. do you know what size vacuum lines are used for all these ill be replacing?

potato

Just to give an update on this, I reran new hoses and used 5mm hose on all. My vacuum is now back up to ~20-22 vs the ~14-16 it was at before. Also the idling issue seems to be related to the maf, after messing with it and retaping it, it seems to idle just fine now after venting to atmosphere.

Thanks derass for suggesting the quicktap instead of welding into the hotpipe.

For anyone who finds this thread in the future, here is my setup:

Left side -- FPR -- T -- boost gauge
Right side -- BOV
Wastegate -- Boost cont. -- Quicktap

Kaifd3s

Second photo looks good. Try to put the source for the boost controller/wastegate close to the turbo on the hotpipe. The closer the better readings for the controller/wastegate.

As far as the boost gauge, I've heard horror stories about running it of the FPR. I have an S14 SR and I just run it from one of the nipples underneath the Throttle Body. I'm not positive but you should have a nipple that you could use for it other than the FPR line.

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potato

I put the quick tap in the first coupler going to the hotpipe. I've heard that also about running the FPR and boost gauge as a bad idea however I wont be pushing serious power so I should be okay.

TheRealSy90

But there's no reason to t into the fpr hose when there should be more than enough vacuum sources on the throttle body.

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potato

I only have 2 on top and 1 (I think) useless one on the bottom. Is there another location you suggest?