Can't build boost

[cartert]

A couple weeks ago I replaced the thermostat housing gasket, radiator, and water pump gasket. While doing so I pulled the CPS. Had a terrible time re-timing it. I followed these steps... http://www.supramania.com/forums/showthread.php?38775-How-To-basic-timing-instructions-CPS-alignment No matter if i turned the CPS ccw or cw a tooth I could not adjust quite to 10 degrees, 12 from one cps setting and 8 from the other was a close as I could get. Noticed my cam marks were slightly to the right of the timing marks. Ended up setting the crank to TDC and 0 deg; moved the cams back a tooth. Finally got the timing right. It didn't make sense to me that I had to move the cams back a tooth when the car was running fine previously.

I have a divorced downpipe.... Somewhere during all this timing I noticed alot of exhaust (mainly because of the increased noise) was coming out of my waste gate dump tube. Also noticed that at idle my boost was reading -15 psi, I normally read -23 to -25 psi. Didn't think much of it at the time. Took the car out and it would not build boost. I hammer down and the turbo sounds rowdy but it won't get above 0 psi and the car falls on its face.

Tonight I took the downpipe off to examine the rear of the turbo housing. I assumed I had the crack that often occurs on ct-26s. There is only the start of a hairline crack, and I was not leaking there or at the waste gate. Also replaced my actuator with one from a buddy which was tested before install. I left the downpipe off because I need to pick up RTV tomorrow. I fired it up and boost was at -15 psi again, so I don't have much hope for my test ride tomorrow.

Anyone have suggestions on what else to look at or check?

 

[supraguy@aol]

Your cam timing is probably off now, which would explain the loss of vacuum at idle. There have been a number of people who suffer crank pulley breakage:
The rubber between inner and outer sections shears, and the outer pulley section(with the timing mark) moves in relation to the inner section. Try retiming your cams, by verifying TDC with a long 3/8 extension or a chopstick, etc. sticking out of the #1 cylinder spark plug hole. This should fix your issue.

 

[supraguy@aol]

Ps- if you find that this is the case, be sure to mark a new TDC notch on your pulley.
Of course, a replacement pulley is a better option, since it could slip again at any time.

 

[cartert]

I appreciate the replies. I checked the crank pulley with a extension in cylinder 1; the extension climaxed right at zero so my pulley hasn't slipped. I replaced a worn hose clamp on the stock bypass valve and the actuator which was previously mentioned. Fired it up and my vacuum was back to -23 psi, great! Took it out for a drive and it'll build boost now.... but it hits cut at 4000 rpm at WOT. Previously I was hitting cut in 3rd gear or above, at around 10-11 psi. Now I can't get through 1st with out hitting cut. I don't quite understand the difference between fuel cut and boost cut or how to determine which one you are experiencing.

It hits cuts at 4000 everytime, if you hold down on the gas it does: brapppp, cut, brappp, cut, brappp, cut, etc. The exhaust smells rich when it cuts out. Boost cut or fuel cut?

All of my little vacuum lines have been replaced in the past year. They did fit snug on the nipples, after multiple heat cycles they have become very easy to slide on and off. Could small leaks around the little vacuum lines cause me to cut like this?

 

[supraguy@aol]

Hey Cartert,
Glad you figured out the issue, and it wasn't the cams/ crank pulley.
I would continue to check all of the vac and boost hoses/ pipes for leaks.