Still losing boost !!

[taki944]

Hi all I fixed the fuel issue compression test was as follows
#1 135psi
#2 135psi
#3 128psi
#4 140psi

I am still losing boost I think some where at part throttle the car pulls good at WOT it wont go anywhere and I here the hiss sputter under the car it fells like I am losing the boost!! Thoughts??

[nize]

have you checked the BOV to make sure it's not leaking?

[taki944]

Originally Posted by nize

have you checked the BOV to make sure it's not leaking?

Where would it leak to does it blow off to under the car or back to the intake. How would I test it ?? Pete

[nize]

check this thread;
Blow off valve question, Please help!

and this one;
Just bought 951 a few questions

and possibly this one;
Acceleration Drop Off Question

use the forum search feature and search for: blow off

[jmj996]

The one that got me this past weekend was the vacuum connection UNDERNEATH a metal section of the air intake leading directly to the intake manifold - just left of the BOV/diverter valve (if you're under the hood facing the engine). Once I got that connected, MAJOR improvement.

Prior to this problem, I was getting pretty solid boost, and then in the middle of a run, under acceleration, I lost most of my boost, it was like it was capped off. I found two vacuum connections that came undone - the one I described above, and the one between the fuel damper and the connection at the intake manifold.

If you really want to eliminate these vacuum gremlins, get a complete vacuum replacement kit with the hoses and connectors and replace everything. I had the Lindsey vacuum hose/connector kit from Paragon with me at the track, and that saved my butt big time. Next step if that doesn't resolve it is to replace the items connected to the vacuum lines - BOV/diverter, fuel damper, fuel pressure regulator, etc. in case any of them have a torn diaphragm (or if you can separately diagnose those parts to confirm they're holding vacuum, even better). If you buy stock diverter/damper/FPR and the vacuum hose kit, you'll spend about $200-$250 total, and you'll have eliminated another source of future problems. My 1986 has 137k and between the previous owner and I, all of this has been replaced.

Good luck!!

[nize]

all you need is a mity-vac hand pump to diagnose vac leaks in the system. another good investment for around $30;

[jmj996]

Originally Posted by nize

all you need is a mity-vac hand pump to diagnose vac leaks in the system. another good investment for around $30;

Very nice, I'll have to borrow one of those some day, that would ensure I've completely knocked out my vacuum gremlins.