Boost Flutter Problems!!!!
 

I got big boost flutter problems, I have the stock BOV's, pfc, turboback w/ a small cat, fmic, and some cheezy hard intake pipes w/filters. I was thinking tps mite be bad, but I could def use all suggestions or help, and it usually happens on WOT or close to WOT, maybe like 4500-5000 all the way up to redline, flutters from between 8 and 10 psi..........

def not the tps...thats throttle not boost.

sounds like you have a perfect boost pattern 10-8-10. does it go down to 8 psi at around 4500rpms and then shoot up to 10 shortly after? then stay at 10psi till redline?

ya but shouldn't it be consistent, like holding 8 or 9 or 10 to redline

it should start at 10 then at around 4500rpms when the chage-over occurs it should drop to 8psi then back up to 10psi all the way to redline

idk if its the way the pfc is set up but it holds 5 from 3 to it switches at like 4500 and jumps to 10 but its flutters rapidly not smooth, every 100 rpm up down up down, its weird cuz it didnt do it stock, or with the pfc, i'm not sure if it was after the fmic or the cheezy ass intakes I got for 20 bucks off ebay, still haven't tuned it yet either????

I was thinking maybe a vacuum leak or a bad solenoid??? or maybe BOV's

yeah those are good guesses...check to see if the bov's are in tightly. if the idol is fine at start up and idol then its most likely not a leak...

a bad soleniod sounds like a firm possibility. maybe someone else on the forum can help you with testing them to see if they are in working order. using a voltege meter and wat not.

thanks again for the feedback

I've heard that a bad cat or clogged exhaust can cause this kind of problem.

Dave

^I could be wrong but I don't think so Dave. Generally a clogged cat would cause the boost to drop off at higher RPMs. You'd be able to hit your target boost at lower and mid RPMs but then it would decrease as you go up the RPMs. Thats what happened when my cat clogged.

axn - you might to try and search on "boost fluctuation". I was searching on that a while back and saw a few good threads. I have an issue where my boost fluctuates between 8-10 PSI but only at the transition of the primary to secondary turbo and only for a few moments until the transition is over. Still haven't figured it out but I think I may have an exhaust leak near the turbos.

i had turbo flutter problem before on my primary. the harder you boost, the louder the fluttering from turbo whistle.

it could be similar. Mine was bearing failure due to my blitz aluminum mesh intake was rubbing and the metal powder shreds got into the turbo, and caused permanent damage to the turbo bearings. So i end up picking up a set of 99spec twins. now its gone and the car pulls hard.

what kind of air filter are/were you running?

It has been suggested to me to check the trubo control solenoids. The ones directly under the UIM with the wire clips and two nipples.

Try adjusting the boost duty cycle on your PFC.