Boost Builds Then Lets Off

ALL4thaN0okie

OK.. I've been having this problem for a while now, but e'er attributed it to my leaking 1g BOV. Now I've replaced that with a Greddy type southward.
The automobile will boost normally to effectually 18-20 psi, as soon as it hits xviii-xx psi the boost will driblet all the mode down to near 0. I have checked for boost leaks and there are none (checked by 25 psi). I take no idea what else could be causing my boost to drop all the mode down, other than maybe my wastegate opening and staying open up?
Any and all assistance is appreciated, as always guys.

Mod list- EVOIII16G, walbro 250, FIC 550s, greddy blazon s, apexi true cat back 3", 1000&N, UICP, stock IC, Joe P MBC

91gvr4 · 160 three Aug 30, 2003 Omaha,, Nebraska

Letting off the gas :tease:

ALL4thaN0okie · 15 2 Mar 3, 2004 Columbus, Ohio

Letting off the gas

I wish it was that easy....

psychlow · 2,866 13 Jun 30, 2003 Colorado Springs, Colorado

What happens if you disconnect the MBC and run the boost source straight to the actuator?

Does the car even so accelerate smoothly (albeit slowly) fifty-fifty at 0 heave? Any black smoke or backfiring? I'yard but wondering if y'all're having ignition issues, which would cause you to not create enough exhaust to maintain boost.

Plugs/wires/coil pack may be would exist suspect if you lot think it may be ignition related.

oldman · nine,794 190 Jun 21, 2003 Dayton, New_Jersey

Where's that safc? Don't tell us you're running the 550s without safc and the 255 without an afpr. OMG

edit: Are you venting as well?

ALL4thaN0okie · xv 2 Mar 3, 2004 Columbus, Ohio

at 0 boost it accelerates fine.... pulls actually difficult (similar it should ) when its building and at max boost for a second.... i've never had any smoke or misfiring either...

sorry i forgot to listing the safc... i have the safc and logger and it's tuned as well as i can get it without steady boost...

i don't all the same accept an afpr.... and i'm definitely not venting the bov..

ALL4thaN0okie · 15 ii Mar 3, 2004 Columbus, Ohio

oh..and in response to your ignition idea.... i have had some random misfire codes in the past..

oldman · 9,794 190 Jun 21, 2003 Dayton, New_Jersey

at 0 heave it accelerates fine.... pulls really hard (like it should ) when its building and at max boost for a second.... i've never had whatsoever fume or misfiring either...

Then what happen when boost starting time to drib? How fast does information technology drop? Noises? Sputtering? Requite united states more.

ALL4thaN0okie · 15 2 Mar 3, 2004 Columbus, Ohio

well.. when the heave drops, it drops quickly.. i dont know how to draw information technology other than that... the turbo stops making a spooling sound as well... the only other thing is that it doesn't make any power (plain) after the boost drops.... i can still accelerate without sputtering or any other problems just slowly

dynatos · 434 nine April 1, 2003 Gresham, Oregon

so when the boost builds - hits xviii-20, goes to 0.. does it start spooling back up imediately? If not, what happens to go it to start spooling again back up to 18-20?

psychlow · 2,866 13 Jun 30, 2003 Colorado Springs, Colorado

oh..and in response to your ignition idea.... i take had some random misfire codes in the past..

I'd starting time with plugs, wires, and coil pack so.

peregrine

and check for heave leaks

truwarrior

When does it starting time to spool? Is the flapper attached to the actuator? Possibly it fell off.

oldman · 9,794 190 Jun 21, 2003 Dayton, New_Jersey

and then when the boost builds - hits eighteen-20, goes to 0.. does it start spooling support imediately? If not, what happens to go it to offset spooling once more back up to 18-twenty?

A very important question. How long does it take for the turbo to start spooling again after it drops to zero? Whatsoever more details during this flow would be swell. I think your random miss fire may take something to do with the lack of afpr, if ignition is the problem you should accept felt some turbulence if not complete close off, it certainly should not have driven normally like a Northward/A subsequently it dropped to 0. I tend to think information technology'due south turbo related but can't figure out why without more than info and testing. I have never heard of a problem similar this, maybe some wiseman can enlighten united states all.

ALL4thaN0okie · 15 2 Mar 3, 2004 Columbus, Ohio

A very important question. How long does it accept for the turbo to showtime spooling again after information technology drops to zero? Whatsoever more than details during this period would be nifty. I remember your random miss fire may accept something to do with the lack of afpr, if ignition is the problem you should have felt some turbulence if non complete shut off, it certainly should non have driven ordinarily like a N/A after it dropped to 0. I tend to call up it's turbo related just can't figure out why without more than info and testing. I take never heard of a problem like this, mayhap some wiseman can enlighten us all.

when the heave drops to almost 0 it stays there until the finish of the gear... or i could let off the gas and then stride on it again it will build again... but.. past itself.. it won't start building heave again..

OddyseusDSM

If its pulling like it should even though the gauge is reading 0 have you stopped to check the judge? I mean, you said it yet pulls hard and in NA style the turbo engine would take less power than a NT. Is your guage an electrical sending judge?

ALL4thaN0okie · 15 two Mar 3, 2004 Columbus, Ohio

information technology pulls similar a geo metro would pull when the boost drops.. it'due south all the same shine though as in not sputtering... basically when information technology spools upwardly.. it feels similar information technology should... only when the heave drops.. there is a major loss of power..but it still accelerates... so i doubt it's the judge... the judge is mechanical (autometer ultra lite) ..

ALL4thaN0okie · 15 two Mar 3, 2004 Columbus, Ohio

another thing that i forgot to tell you lot guys is that it'll hold boost longer with the college gears.... 3 holds longer than two ..4 longer than three... 5 longest of all... i'chiliad not sure if that'll aid at all...

oldman · 9,794 190 Jun 21, 2003 Dayton, New_Jersey

another affair that i forgot to tell you guys is that it'll agree boost longer with the higher gears.... 3 holds longer than ii ..four longer than 3... 5 longest of all... i'grand not sure if that'll help at all...

So it's rpm related, what rpm? What happen if you lot go role throttle at like 15 psi?

ALL4thaN0okie

its somewhere between 4000 and 4500rpms .... part throttle or full throttle doesn't matter... boost still drops at the same charge per unit....

oldman · 9,794 190 Jun 21, 2003 Dayton, New_Jersey

I propose doing a pinch test and go from in that location.

AllWheelPeel · 4 0 Aug 10, 2003 Rhode_IslandUS

I have an 89' dodge colt turbo west/a 1.6L 4g61 (The start edition grandaddy of all these cars)
that is exibiting the verbal same symptoms. Upon pulling information technology apart I found three things wrong.
1. The nipple on the heave solenoid was busted off allowing the boost to flash loftier .
afterward that ,I'm guessing that the ECU was pulling timing severely.
2.The exhaust manifold and turbine housing are both cracked.Simply the rotor spins freely.
3. My o2 sensor is dead.
I am currently changing everything over to 1g DSM stuff that came off my Talon (14b, etc.)
While I realize that I haven't answered your question directly, I can offering some ideas.
I will post once more soon when its back together.

truwarrior

maybe you accept a kink in your boost judge line, mine does now and my vac reading is all messed up

dynatos · 434 9 Apr 1, 2003 Gresham, Oregon

I would recollect a damaged nipple, teared line, cracked manifold, etc would exibit more than of a a constant consequence. Such as just hitting maybe iv-5lbs of heave.. or the auto always running horribly, etc. Sounds similar the ECU is seeing something it doesn't similar, and is telling the BSC to cutting boost. You lot shiift, or let of the gas and endeavor again.. readings change, and the ECU tries again. Are random misfire codes all you're logging?

vtracer20 · 407 0 October 1, 2004 Milton, Vermont

it sounds to me like something is leaking...like it spools and at a certian psi something gives and deceit handle the psi but it'southward evidently something small....bank check all ur piping connects...

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