So last year November i got my FD tuned @ 13.7psi problem free with out a boost controller running on manifold pressure. i tuned my car at sea level ( im pretty sure it's sea level at least....) and drove 2hours back to chicago boosting occasionally. Well pretty much the next day the weather dropped into the 30's drove my car around boosted and of course i had the boost spike like whoa. so fast foward to the warm days.

The first warm day there was i took the car out let it warm up like i always do. drove around in 60+ weather and boosted with a hella spike to about 16-17psi while hitting fuel cut. WTF... So i purchased a .9 bar (13.5 psi or something close to that.) spring from tial, pulled the Wastegate out and replaced the WG spring. tested it out and spiked to about 17psi again.

So i pull the WG off again thinking could i have installed the WG spring wrong . thats when i noticed the top of the WG assembly was loose from the bottom part.

So your looking at my WG the red part moves from the bottom part where the exhaust flows.

I took the entire WG apart and re-assembled it back together and tightened anything i thought was loose on the WG

So im running out of idea's. i have checked my vac line that run from my manifold to the wastegate and even the vac line that goes from the BOV to the UIM and nothing any idea's...... i have done everything short of putting my hallman bc back on. the only other thing i can possibly think of is the WG not sitting in right on the manifold or the down pipe. ( my WG is routed back into my exhaust. )

 

Boost spikes can be attributed to a lot of other things besides the spring. If that top was loose than the valve stem could jamb and that could have given you a spike, but if that were the case you would have seen that when swapped the spring.

Wastegate placement on the manifold, dump tube location on the down pipe, turbine wheel, turbine housing are going to be the most obvious reasons for uncontrollable boost.

Are you using a one-off setup or something off the shelf??

 

im on this old school A-spec manifold and down pipe set up with a T70 T4 non-divided. the problem is when it got first tuned It never over boosted...

 

I would move the pressure source to the compressor housing. Then pressure check the line with low air pressure.

 

how can i go about doing that ?