backspinning turbos
 

Ok, I've been trying to solve this boost problem with my sequential system for months with no avail. My primary would spool up perfect to 10 psi but then at transition, I would lose all boost, and if I stayed on the gas for more than a second or two, then you could hear the secondary turbo backspin when I let off the gas. I cant figure it out. I took it to Performance Buyers Club in Chantilly, VA, and they had no idea what was going on. So over the weekend, I switched over to poor-man's non-sequential to see how everything would run like that. Now only about 1-2 psi of boost reaches my UIM to the boost gauge, but i know that my turbo's are spinning, cause you can hear them spool, and you can hear that horrific noise of them backspinning when I let off the throttle. They are obviously spooling into a wall, but i cant figure out what that wall is. My charge control actuator rod is out, which means that the valve is open, so it's not that. I cant think of anything else that could be blocking it.

Any one have any idea's or input on what i should check next?

I think it would be good if you can take a sound clip and let us hear it.... you sure its not the sound of your air pump???

yes, im sure... it is a loud whistling noise that starts as soon as I let off the gas. I may try to get a video of the car, in which you could see the boost do nothing, and hear the backspin afterwards.

very strange...you have a bov on there right? stock, probably?

Oh, and it only does it if i give it boost. the longer and harder h hit the throttle, the louder the sound is.

HKS SSQV... works fine. when i had the turbos running sequentially, like i said, the primary worked fine, and the blow-off worked fine as well

did you go through all your vac lines?

You are non-seq and do you still have your CRV hooked up?

It really sounds like all your boost is venting through the CRV. It will make a loud whistling kind of sound when that happens.

a couple weeks back, i removed my UIM and searched through all the hoses and everything, because i thought that one of the vacuum hoses to the Charge Control solenoid might have been cracked or something, causing my Charge Control Actuator to stay closed keeping my secondary from spooling. all the hoses were fine, they actually seemd almost new, still really soft. and i dont think that is the problem anymore, considering now that it is set up non-sequential, the charge control actuator isnt even used.

no. i checked the CRV when i was still sequential, and it was not venting boost. and now that i am non-sequential, i have the CRV removed and the y-pipe hole capped.

Ok, so you've removed the CRV, the charge control is wired open, and you still can only make 1-2 PSI with a loud whisling sounds coming out while on boost.

You have checked, and rechecked, your y-pipe and other IC couplers for rips or tears? Is your HKS BOV mounted on IC piping or connected to a hose using a flange?

my money is it on being couplers

i have checked all my couplers, and they are fine. there is no sound of a boost leak, the only time i hear the loud whistling noise is after i let off the throttle. not while boosting.

the BOV is in the stock location.

and that loud whistling noise after throttle isn't the BOV, right?

Try sticking your old CRV in place of your HKS BOV and see if the problem still exists.

i tried replacing it with the stock ABV a few days ago and it was the same. Im assuming the CRV would be any different.

And you verified there were no problems with either line running to the BOV?

im not sure what you mean by "i can hear the turbo backspooling"

I've ridden in a turbo mustang that had no blow off valve and between shifts or when he let off the gas the turbo would make a terrible, almost like a studge laughing" noise. Thats what I'm picturing your noise being but that still wouldn't explain the 0 secondary boost.

it makes a loud screaming sound, almost like a siren... its hard to explain, i'll try to get a sound or video clip of it a little later tonight. i was told by some others that that is what the sound was

Ok. i have a vid of the car boosting to about 2 psi and the sound after i let off the throttle... it may be a little quiet in the vid, but you can definitly hear it.

http://www.we-todd-did-racing.com/we...ZmQzMXk1NDE%3D
(sorry for the shakiness, its hard to hold a camera steady while driving, even if just going around a parking lot)

also, a little update. i am 99% positive that that sound is the sound of the air being forced back through my turbo... which means all that pressure is being blocked by something and not getting to my motor. i started disconnecting intercooler piping and stuff, then running it real quick to try to find where this blocking is taking place, and i found that if i disconnect the intercooler piping from the elbow, i dont get that sound, which means that whatever is blocking the air, is something between the elbow, and the UIM... which could really only be one thing. the throttle body. i dont know much about the whole double throttle tihing in the car (just about the only part that i havent done extensive research on) but i'm thinking it may have something to do with that. maybe one of the butterflies is sticking closed and not allowing enough air through? i dunno. maybe someone could give me a little more info about how that whole thing works?

Anyone?

hmmm that is a very strange sound. it does sound like it is surging (the only time i have heard that before is when people do not use their bov, sounds cool but its hell on your turbos!). i dont think that your butterflies have anything to do with it other then that they close like they are suppose to and the air slams in to it with no place to go.

im pretty sure your bov are not venting the air properly

have you tried to take off your hood, put the stock bov back on and getting a very long hose and routing it in to the cabin where you can have someone make 100% sure that they are working. i think this is the only way your gonna beable to make sure that they are. how is your idle, are you sure you dont have a air leak which is past your throttle body?

check your blow off valve?

Are you absolutely sure that you have your vac lines hooked up properly? I'll look at the dig I have at home and see if the is anyway that the system could do this.