Anyone get a P1103 code? maybe some compressor surge!!

[Allen fong]

I was enjoying some nice weather and upped the boost, was holding steady around 25psi then popped this code, (P1103) cleared it and hasn't come back on. I did notice the other day while going up a hill i had some bad compressor surge, this was under part throttle and felt like the front end was going over washboard. Is the compressor surge fixable without turning down the boost? is it a Bov thing? i have a greedy type s without the lower vac hose connected. Or can it be the waste gate?

[Brett Haviland]

thats to do with a wastegate diaphram malfuction..  Probably because the ECU is trying to lower the boost, and cuz you have a aftermarket controller (do you) controlling the boost it sees too much and with throw that code..


As far as the compresser surge... You say its happening at a partial throttle cruise??  How much boost?

The Greddy bov sounds like its hooked up right (bigger top vac line connected to PORTED vaccum).  Where does the BOV vac line get its vac from?  the stock nipple?  One time i used the "P" vac line thats on the throttle body... but the hole is SOOOOO small it wouldnt allowe enough vac to the BOV at higher boosts and the BOV would flutter/surge like crazy.  I ended up drilling/tapping a bigger sized l?nipple on the intake manifold (ported vacuum) and it worked great after that. What kind of wastegate do you have??? interna;?

[Allen fong]

Yes sir I am running a AEM TRU boost gauge/controller. the surge happened at part throttle up a hill at about 25psi (i had my boost cut set at 28 psi and it went off.) i was just backing off on the throttle and the surge continued for a few seconds. the BOV is connected right to the port on the manifold behind the throttle body. I am not running the lower hose on the BOV. I am just running a stk internal waste gate. I should note the bov does open on light throttle release low rpm shifting i can hear it open.

 On a side note i've noticed that my gm 3bar map reads different than my AEM gauge? e.g. at idle -11 on gauge and logging with evoscan i get -5. Seems to be off 5 psi while driving??

[Brett Haviland]

yeah at a partial throttle situation like that i have experienced a bit of compresser surge as well.  Its pretty normal running higher boost like that.  WIth the throttle plate closed a fair bit... and the turbo spooled up that high its trying to push a lot of air into the engine but it gets stopped by the partially closed throttle plate so the air "surges"  (forces pressure back against the compresser)

  As long as its not doing it at a WOT pull you should be good... or right after a hard WOT pull and letting off, both are bad for the turbo bearings.