Boost not constant

[1stTurboGN]

I cant figure this one out.... If i hit the gas half pedal, for example, my boost will hit 10# but then drop right down to 7# then back up to 10....then back down to 7, all in the matter of a few seconds. It does this at any amount of boost, say 16,13,16,13 etc. It only does this some of the time, but im trying to figure out what it is so it doesnt happen when i really need the boost. dont want any ricers going home thinking theyve got something.... any help is appreciated! thanks

 

[turbo2nr]

What down pipe/waste gate are u using? Stock wastegate solonoid? How about a boost controler? no?

 

[1stTurboGN]

TH 3" downpipe with the built in wastegate, stock solenoid and a boost controller under the dash

 

[turbo2nr]

well, it could be only a few different things. Maby a sticky wastegate swing arm. after car has warmed up, take off actuator arm and check for free movement, Wrong type of fastener on the swingarm, (don't use a paper clip, aligator clip, etc. ), electronic boost controler has bad wiring/malfunction. Remove it and try. Check for boost controler "T" orientation (vac lines, oriface) Maby wastegate hole in turbo is wrong size in relation to puck size? Maby your boost guage has a leaking line?

Scott

 

[1stTurboGN]

the actuator arm moves freely, although i use an alligator clip... my boost controller isnt electronic, it is the type where it is just a knob and a vaccuum line (sorry i dont know the right name) the wastegate and puck size are definately right because i made sure of this when i installed the turbo and downpipe a few months back, and im positive the gauge doesnt have a leak because you can hear the turbo drop off and come back when this problem happens. i wasnt quite sure what you meant with the "t" orientation...could you explain that a little more? but i am kind of hesitant to think that it is a vac leak because it only happens every now and then. thanks for the help again.

 

[turbo2nr]

May be hard to believe, but I think it is your aligator clip! I have read this many times and seen it myself at a track on a guys car. Try to locate the correct clip. Worth a shot. I have been told this by John Craig himself.

Scott

 

[1stTurboGN]

i had 2 of the correct clips and they both flew away when i was trying to put them on...theyre a pain in the a$$, but ill give it another try...thanks for the help!!

 

[1stTurboGN]

got rid of the alligator clip..... still the same problem. I was thinking maybe the wastegate solenoid arm was adjusted wrong? how should it properly be adjusted with the in car boost controller type setup? (not electronic)

 

[turbo2nr]

I guess you have a valve in car to bleed off pressure. Try removing it and just using the normal method. Start of with the rod adjusted one turn in, from a loose fitting.

 

[1stTurboGN]

Ill give it a try, hopefully today....thanks for the help TURBO2NR

 

[XLR8]

What you are discribing doesn't sound out of the ordinary to me. It is very hard to control/modulate the amount of boost with the gas pedal. Does boost stay at a constant level when you are at WOT? If so you are probably in good shape.

 

[1stTurboGN]

XLR8- im sure it is out of ordinary only because of the fact that i get these symptoms some of the times...not always. im not sure about wot but i know that i can build constant boost at any level some of the times and it fluxuates the other times.

 

[microELVIS]

My boost was doing that same thing when I had a tiny axhuast leak right at the flange of the passenger side header on cylinder #2. Everything was tight, but there was a hole right at that spot where the flange and tube come together. It made the boost fluctuate.