Any one get boost spikes showing on their gage during decel?

I have GT2860RS, newly built motor etc, internal wastegate and greddy BOV - tried two things (removed 1 spring from the bov - originally had two in parallel) so it's cracked open at idle, and even opened the wastegate a bit 15% or so and was still seeing a spike where pressure jumps from full vacuum to 5-6psi for a short time sometimes coming right back down, other times holding for about 1 second or so. Went out and drove it, had noticably more lag in spool time but the gage still acting erratic in decel.

Let me preface this with:
internal gate starts to move at about 5-6 psi (static testing)
wastegate signal line is about 1 foot after the compressor outlet

I did realize that I have not yet installed the orifice (restrictor) for the boost gage that came with it for erratic type gage movement but I don't necessarily think this is it...

The compressor doesn't seem to be surging or making any obvious surge sound during this time or after shifts - just nice bov sound if i'm on it a bit.

What are the thoughts here? I'm going out for another short drive to test the boost gage restrictor

Edited 1 time(s). Last edited Monday, April 19, 2010 7:35 PM

If your reference for your boost gauge is after your throttle body, I would be questioning the reading of the boost gauge. What does your MAP sensor say, is it 5-6 PSI as well?

Wagonwes wrote:If your reference for your boost gauge is after your throttle body, I would be questioning the reading of the boost gauge. What does your MAP sensor say, is it 5-6 PSI as well?

It is after the throttle body or "after the throttle plate". I don't recall seeing it on the MAP sensor at all now that you mention it - I'll have to go check some decel logs for it to be sure.

Yea, I bet is your boost gauge, but you have to check your logs to be certain...