raptorse68

ok so i just got done installing a ls6 intake and a walbro 255lph fuel pump. after start up it sounded like there is a serious vacum leak somewhere, but we could not find one. so we took it down the road and when i got on it it actually felt a little slower and at about 4500rpm it felt exactly like the car hit the rev limiter. now for the noise, i don't know if it sounds different then a ls1 intake under the hood or not. but with that whole problem with it feeling like the rev its bounceing off of the rev limiter i have know idea if it is the tune because of the new intake and fuel pump or if i just screwed up some where. my mods are below. any input would be greatly appreciated.

-2004 6.0L LS1 shortblock, freshed 4000 miles ago with new rings/bearings
-TEA stage 1.5 5.3L heads w/hand finishing
-222/224 cam on a 115 LSA (idles like stock)
-Comp cams 987 valvesprings
-Comp cams Ti retainers
-Z06 injectors
-Z06 clutch
-2001 T56 tranny
-4.10 gears
-hooker longtubes w/Y-pipe
-Corsa catback (stainless)
-ls6 intake
-walbro 255lph fuel pump

thanks ben

TheBlurLS1

iTrader: (8)

Did you remove the coolant pipe from under the manifold? Did you break the clips off of the knock sensor harness that's under the manifold? If you didn't replace the coolant pipes with a front pipe and rear plugs, you're intake manifold is probably not seating on the heads correctly.

LS1howto.com has a nice writeup about the swap.

Other sources for vacuum leak is the brake booster line, MAP sensor hole, a/c vent door vacuum line, fresh air tube (from valve cover to throttle body) and PCV valve hole. If you're sucking in too much un-metered air, it could lean out and not have enough fuel to run past 4500rpms.





If you've got a fuel pressure guage, you can check the pressure while its under load and make sure you're good on that end, but I'd go with the vacuum leak right now.

Jditlfm

iTrader: (26)

good call on those lines i did the intake swap with ben and i can tell you i didnt do that and neither did he, so its deffinitly not setaing right, witch would explain the vacume leak sound. thanks a ton.

TheBlurLS1

iTrader: (8)

You're welcome sir!