06-27-2006, 12:24 AM
Join Date: Mar 2006
Location: Edmonton, AB
Total Cats: 0
Stumble on boost
Stock greddy manifold, turbo and DP.
Starion I/C with JimB pipes.
VTA Bosch BOV with check valve
JimB MBC (connected between outlet on turbo and WG)
MSD 2225 aux fuel pump
FM O2 Clamp (not installed)
323 GTX PCV (plumbed into intake)
I'm running 7psi. I've tuned the AFPR to have ~37psi at idle, ~50psi with vacuum line disconnected. I have added the restrictor to give me more fine control over rate of rise. At full boost I'm seeimg just almost exactly 100psi. So I think I'm pretty close on fuel, while being a little on the rich side.
The car runs great, pulls nice and hard. Boost holds very steady at 7psi. The BOV seems to be doing it's job, when I lift under moderate boost I get a nice whoosh, under heavy boost it lets out a higher pitched whoosh (chirp, whistle).
The issue. Mostly have noticed this in second gear, but is present in third just not as pronounced. Under boost if I go from WOT to partial throttle I get a stumble and the car jerks a bit until I either completely lift or go back to WOT.
I have two thoughts on this. Change the BOV from VTA to recirculating. Maybe I should do this anyway? Or maybe the O2 clamp will smooth things out a bit.
Any suggestions? I really want to get on the dyno and make sure my AFR is on target and up the boost to 9-10psi. Before I do that I want to get the car running as good as possible (Dyno time is 180-200 per hour).
Once again, excellent resource we have here!