help, i'm stumped.
 

Like a week ago when driving home from Corpus, I was passing a pick-up....and when i was most of the way around him the Z like boosted incredibly quick all of a sudden followed by a popping noise and no more boost. Right after the car is making this very loud sucking noise that sounds like it's coming from only one piston. The car still idles and runs fine other than that loud noise and no boost. My first thought was I blew something in the motor (which would like way suck since it was recently rebuilt)....so after a compression test it showed 180 across the board. Okies...not internal....moving along, i replaced the intake/exhaust gasket thinking it was there since i could smell exhaust faintly. Nope...the problem is still there so like i'm stumped. Oh, and this is a 1983 280ZX turbo.

I know this video is kinda horrible, but this is the noise... http://s8.photobucket.com/albums/a32...t=DSCF0007.flv

Yowsa! That's a bad exhaust leak. Did you inspect the exhaust ports on the head, the exhaust manifold, and turbo when you had it all apart changing the gasket? It might be a cracked exhaust mani, blown mani to turbo gasket, or maybe a cracked turbo exhaust housing.

Do you have an a/f ratio gauge? I'm wondering if that was caused by running too lean... ever any backfiring? Running stock boost?

it does sounds like one individual cylinder.... I think the cracked (or blown chunk) of exhaust manifold sounds right. That may also leak pressure and prevent the turbo from spooling up.

Sounds like my Z's exhaust when I blew a head gasket. It wasn't enough to have oil mix with water, but it was letting combustion gases leak by.

then what explains the sudden spike? potential wastegate actuator problem?

wouldnt be headgasket as her compression is at 180 across the board. it would show up one dead if it was hg. id say manifold or is one sparkplug blown out its hole. ive seen that on ford engines, sounds about the same too.

JESUS you take forever to start a car. and did you learn how to film at the blair witch project cinematography school? lol. but yes you most definitely have a HUGE exhaust leak. so start by fixing that.

:024: