Thread: Vac line or BOV problem?

I am still have issues with compressor surge and have tried two different BOVs so I am thinking the lines are run incorrectly. I am getting a reading of 18-19 in. hg. on the boost gauge and have looked at the vac line routing of the bluebird and gtir engine countless times. However I have a USDM de+t and cannot find the charcoal canister. Here are pics of how my vacuum lines are currently setup. Please help me get this sorted out.

i vote for the vacuum line ,i have a hks ssqv and i ran my line to the same spot and alls i would get is compressor surge, then i used a larger line and a deticated line for the bov and used a larger vacuum port source and that fixed my problem.

i recomend using a deticated line for the bov itssself and use a larger vacuum port on either the throttle or manifold, that should solve your problem

also you can T off the bov line if you use a larger vacuum port it will still work fine

Yeah, you can put the BOV signal anywhere you get vacuum. Having struggled with compressor surge in the past, I prefer using the fat brake booster line (just watch out for the check valve).

You can rent a vacuum pump at AutoZone to test your BOVs. If they aren't opening until 15-20inhg you'll likely have some surge no matter how good your vacuum signal is.

Does anyone have a diagram of vacuum routing on a USDM engine. As I mentioned above, all I can find are of the Bluebird and GTIR but not mine and I don't think I have a charcoal canister and if I do then I can't find it. I guess I am just needing some detailed help. Thanks much guys!

Do you suggest tapping the brake booster line in any certain place?

You can see my tee back there near the firewall. Just be sure you are on the side that connects to the motor. The other side that runs down to the brake booster itself has a check valve in it.

I can't remember the exact sizes I used, but the brake booster line is something like 1/2" hose. Then the line I ran to the BOV was pretty fat, but a little smaller... probably 3/8" or so. So I got a 1/2"x1/2"x3/8" tee. You get the idea. Then, since the BOV nipple is a smaller size, I used a short section of smaller hose inside the end of the 3/8" line to connect to the BOV.

thank you Swiss! That pic helps a ton. I really like your engine bay, it looks nice and clean.