bewstin
Proven Member
- 131
- 0
- Dec 4, 2012
-
Groton,
Connecticut
Alrighty, so basically my problem is my turbo spools to 4-5psi, and wont spool to it's setting (12psi) until the RPMS get up to like 4500-5k. I feel I've narrowed down the problem to a Boost leak. Problem is, I've never properly been shown how to do a Boost leak test other than what I've read or seen on the forums. I made a boost leak tester a few months back, works good, and I've used it before to find major leaks. Right now I'm pretty sure I'm chasing down a small leak, but cant get the system to hold pressure. Now, when i fill the BLT with pressure using a air hose off my compressor, it pumps up the system great, But I cant get it to hold any psi. It just leaks out of my valve cover breather hose, pretty slow but enough to not let it even register 10psi on the air hose gauge. I imagine this is because the pressure from the intake manifold is leaking through the PCV valve into the valve cover. I can't really hear anything else leaking, but it's hard to tell because of the leakage from the valve cover. I've triple checked all my vacuum lines and inter cooler couplers.
The reason i think i have a small vacuum leak:
---Rough first 20 seconds after a cold start, w/ boost gauge bouncing between 5 and 15 vacuum, feels like it misfiring, AFR is solid 10.0. After about 15 seconds AFR goes up to 12ish and idle smooths out a little bit. after about 5-10 more seconds AFR goes up to 14.5 and car idle's smooth. Once car is up to temp, vacuum bounces between 19 and 21 vacuum slowly, with the AFR bouncing between 14.7 -14.3 constantly. I'm pretty sure the rough start is because of the EGR delete and its cold outside.
--- Front o2 is brand new and working, Coolant temp sensor is brand new and working, Brand new BPR7ES plugs, and NGK wires.
--- Brand new FP manifold, so no pre-turbo exhaust leaks. All bolts from manifold and head and manifold to turbo are on and tight.
---Boost lag, WOT in any gear other than 1st, the turbo will spool to 5psi. Then when the rpm's get up to 4500 -5k the boost climbs to 12psi, which is where i have the MBC set to.
---AFR's are 10.0 in boost, whether I'm lightly on the throttle in boost or WOT, the AFR is 10.0 the whole time, until i get to 5k ish it hits 10.8, 11 at the most.
---Cruising AFR is 14.7-13.5 depending on hills or flat.
---Stock fuel system
So I'm lost, does it seem like a boost leak?? I'm getting very frustrated, this seems to be my last little problem before i go to get tuned. I'm waiting to put in my DSMlink v3 full, FIC 1200's , walbo 255, and Fuel labs FPR until my tune date which is 1/5/13. It's a 2 hour drive and will cost me 600$ between gas and the tune, which is why i want my car perfect before I get down there. Sorry for the novel, but the more you guys know the more you can help. Thanks
The reason i think i have a small vacuum leak:
---Rough first 20 seconds after a cold start, w/ boost gauge bouncing between 5 and 15 vacuum, feels like it misfiring, AFR is solid 10.0. After about 15 seconds AFR goes up to 12ish and idle smooths out a little bit. after about 5-10 more seconds AFR goes up to 14.5 and car idle's smooth. Once car is up to temp, vacuum bounces between 19 and 21 vacuum slowly, with the AFR bouncing between 14.7 -14.3 constantly. I'm pretty sure the rough start is because of the EGR delete and its cold outside.
--- Front o2 is brand new and working, Coolant temp sensor is brand new and working, Brand new BPR7ES plugs, and NGK wires.
--- Brand new FP manifold, so no pre-turbo exhaust leaks. All bolts from manifold and head and manifold to turbo are on and tight.
---Boost lag, WOT in any gear other than 1st, the turbo will spool to 5psi. Then when the rpm's get up to 4500 -5k the boost climbs to 12psi, which is where i have the MBC set to.
---AFR's are 10.0 in boost, whether I'm lightly on the throttle in boost or WOT, the AFR is 10.0 the whole time, until i get to 5k ish it hits 10.8, 11 at the most.
---Cruising AFR is 14.7-13.5 depending on hills or flat.
---Stock fuel system
So I'm lost, does it seem like a boost leak?? I'm getting very frustrated, this seems to be my last little problem before i go to get tuned. I'm waiting to put in my DSMlink v3 full, FIC 1200's , walbo 255, and Fuel labs FPR until my tune date which is 1/5/13. It's a 2 hour drive and will cost me 600$ between gas and the tune, which is why i want my car perfect before I get down there. Sorry for the novel, but the more you guys know the more you can help. Thanks
? It sounds like you still have a MASSIVE boost leak. Next time you test it your goal should be to build 20psi. It will naturally leak out pretty fast at that level, maybe 1psi every 1 or 2 seconds, but once it hits around 10psi it should take it awhile to leak the rest out. If not there's a problem somewhere.
This is starting to drive me insane, i just want to get rid of boost leaks so i can get my tune already!!! 
Boost leak was done when the motor was cold, and i can imagine the rings are bad, they were gapped within spec (.008-.020, i gapped comp ring at .018 and scraper at .022) and the car has good compression. When i had the engine rebuild i did not have a valve job done, wonding if excessive carbon build up on the valves could cause my problems...
