So... Major boost-spiking after EBC install etc...
 

My "new" ride is an '87 Turbo II. Mods are:

rebuilt/streetported motor with RA apex seals and 15k miles.
9.4:1 N/A rotors
STOCK turbo w. ported WG
Walbro 255
____ 750cc secondaries
R-Tek 1.7
Greddy Profec B EBC
2.5" DP/MP to dual Apexi N1's
etc. etc. etc.

I recently installed a Greddy Profec B EBC and decided to 'tune' it tonight. I've had it turned 'off' the past couple of days, just to get familiar with the "base" PSI using just the stock WG setting. :) The most I would see at WOT in 3rd/4th gear was a solid 8-9psi with the EBC off.

So before I fiddled with it, I 'centered' the "gain" (rotary knob) and turned both the 'low' and 'high' boost settings all the way counter-clockwise, or OFF.

I began doing WOT, 3rd gear pulls and one of the 1st things I attempted to fix was the 'natural' high RPM boost bleed-off, by adjusting the "gain" setting. IIRC, turning the knob to the 'left' helps keep the boost 'up' in the higher RPM's. So I then started slowly turning both the 'gain' and 'low' boost settings up, with the overall goal being a solid 13psi.

Well, I ended up turning the gain knob almost FULLY counter-clockwise, just to see what would happen--and nothing did (at least that I was aware of). But several 'runs' later I did a hard 3rd/4th gear shift (I had not done a WOT shift up until this point). Well, it held a solid 13psi (bleeding off to 10psi by redline in 3rd gear), but when I shifted into 4th gear, I heard the stock BOV vent, but as soon as I mashed the pedal, the boost spiked immediately to 16psi and the turbo sounded VERY loud... :eek:

This was the strange turning-point, because after this strange 'shift' incident, the car began wanting to creep to 15psi on EVERY run after... I had changed nothing. One moment the car was holding 13psi and bleeding to 10, the next moment the turbo was sounding very 'spooly' and immediately creeping to 15psi on just a lower RPM 3rd or 4th gear run...

So I turned the boost controller OFF and was hoping to see the 'normal' 8-9psi... Nope.

It didn't help at all :confused:, the boost still wanted to creep to 15+psi with the EBC OFF.

I pulled to a nearby grocery store and allowed the car to idle. Well, the idle was poor--so I assume that there is a hose/vac line that's popped off. Only problem with a popped off IC hose etc., is that; wouldn't this HURT the boost response? Right now, it feels like the WG is stuck shut...

Tomorrow I'm going to disconnect the EBC to try and eliminate a variable.

But other than that, I believe I should be looking for a vac. leak (poor idle). But what could've happened on that 3rd to 4th gear shift that's now causing this insane boost-creep?

Thanks peeps.

check the vac hoses to the WG and EBC

Alright... I fixed the problem. That stupid *L* nipple on the compressor 'cover' (feeding the WG) popped out. But it's weird because this happened on my old hybrid turbo setup, but the effects were different.

On my hybrid (when the *L* nipple popped out) the turbo had EXTREMELY slow boost-response, the boost would bleed off the 6psi by redline and the MAX boost I could hit in any gear was 12psi.

This is almost the exact OPPOSITE of what was happening last night. Last night the boost built like crazy and would spike uncontrollably--way past 12psi. Not that it matters anymore, but does anybody have any theories as to why there would be two different results from the same issue?