Overboost..

BMFB

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Ok, so im running code 59. i have my waist gate set up, right now to run no more that 8 PSI, adn i have my duty cycle set at 0, and the amounts that it can correct also at 0 9 im just seeing how low it can go, for tuning purposes) any way, ill give it full throttle, and my boost will go to about 8, and then within about 3 seconds build up to about 15, and the whole time ill eb watching my knock retard and that seems fine, but its not controlling it. I do see on my waist gate duty cycle that it is staying at 0, and not moving.

I have an aftermarket boost gauge, and at idle im getting like, 20 inches of hg, so i don't think its a vacuum leak, at least its not obvious. but im wondering if the solenoid itself can be bad, or how to test to see that it is working properly, or if you guys had any other ideas
 

bezerk

New member
Re: Overboost..

if you are running a stock solenoid, take off the connector at the plug and it should show you 7 psi (base boost)
 

BMFB

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Re: Overboost..

it doesn't, it does the same thing.

i took my waist gate actuator off, the lever part of the gate that sticks out of the turbo housing seems to move about 45 degrees total, and it seems very free moving. I took the vacuum part off as well, and it doesn't seem to have any leaks, i took my air compressor and had it turned on to bleed air and put that gently to the port and it seemed to open and close smoothly with air. I also pulled it out and held my finger over the port and it seemed to hold pressure, so that part also seems ok.

People always told me about a spring down there, but i didn't see one...just the actuator, the rod, and an the adjustable end, i thought about turning that a bit out and making it longer, but i have a feeling its not my problem.

now, what about the solenoid itself. what should its internal resistance be? and more importantly, can it be causing my problem.

this truck does have a gutted cat and a more free flowing exhaust than stock. But, im running Code 59 and have been told that i can adjust for this through the waist gate duty cycle. I was just wondering if what im running into is normal. it seems a big jump for that standard 7 or 8 minimum PSI to a minimum of 15 at WOT.

i will say until WOT it seems to hold at around 8-9 psi with no problem.

eh?
 

WyoSyclone

Active member
Re: Overboost..

I'd take the rod off the wastegate arm and make sure the wastegate isn't frozen in position. The stock wastegate setup is marginal and with a gutted cat you're probably running up against what it's able to control. Dig thinks the stock solenoid may be marginal as well... I've got a heavy duty replacement to test but haven't gotten around to it yet.

I've got a couple of DM runs from my Sy with WGDC and KDCSTEP set to zero.... I'll look at them tomorrow and report back. I've got the RPM Stage1 turbo, but if I remember right I still get up to about 11psi with everything zeroed out.
 

BMFB

Not to scale
Re: Overboost..

my waist gate seems to swing free and easy, although the stock boost controller only opens it about 3/4 the way it could be opening. everything in the system seems to be working as it should though, i took it all apart and checked it all out. (is taking the battery out a pain for others too?) when i drive it, it seems to be fine until i give it WOT, and then my minimum boost rating is 15ish...I don't know how i feel about this, as Im planning on running 18, it seems like something i should fix though.

is running a BOV a good idea as a just in case method of control? i have my truck set to shut down at like, 19 PSI, and i don't seem to have any real knock retard at those levels, )whats the thresh hold for needing alky BTW?) But would a BOV save me from having to port the external waist gate, or save me from replacing it? (I really dont know much about BOV's so hopefully that doesn't come off as straight ignorance)
 

Phil O' Dendron

New member
Re: Overboost..

has anybody here tried that device?

tn4_2135212.jpg

http://www.gfb.com.au/turbo-fuse

does this work?

if it does, maybe it could help your overboost problem.
 

turbodig

Active member
Re: Overboost..

I had a stock turbo with an open exhaust and no wastegate flapper at all in it- an open hole.

It still made 10-12 psi.
 
Re: Overboost..

my waist gate seems to swing free and easy, although the stock boost controller only opens it about 3/4 the way it could be opening. everything in the system seems to be working as it should though, i took it all apart and checked it all out. (is taking the battery out a pain for others too?) when i drive it, it seems to be fine until i give it WOT, and then my minimum boost rating is 15ish...I don't know how i feel about this, as Im planning on running 18, it seems like something i should fix though.

is running a BOV a good idea as a just in case method of control? i have my truck set to shut down at like, 19 PSI, and i don't seem to have any real knock retard at those levels, )whats the thresh hold for needing alky BTW?) But would a BOV save me from having to port the external waist gate, or save me from replacing it? (I really dont know much about BOV's so hopefully that doesn't come off as straight ignorance)


What you want is an external wastegate, not a BOV. The stock turbo uses an internal(or is it integral?) wastegate. Here's a little bit of info for ya.

Yup, the noise is just the compressed air being forced backwards through the turbo when the throttle blades slam shut. A BOV will vent this extra pressure out instead of forcing it back through the intake path.

A wastegate is on the exhaust side of the turbo. It controls how much exhaust passes through the turbo, which in turn controls how fast the turbo spins.
 

BMFB

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Re: Overboost..

how big of a pain would it be for myself to port my wastegate, also, how effective. i really would like to keep the stock setup, just so i can use tuner pro to control it and monitor it
 

BMFB

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Re: Overboost..

From what im told for a truck with no cat and an aftermarket exhaust this is normal, is it not?
 

BMFB

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Re: Overboost..

I made sure my wastegate opened, and its very free and easy moving, i know it at least works because it can control boost with no probs until i give it WOT. I made sure my vacuum controller worked, and doesn't leak. my boost control solenoid does have resistance in its coil, although if someone out there could check the resistance of there working boost solenoid i would love to compare the two and make sure they are the same. I know its getting all the pressure it can from my turbo, what else can i check?

EDIT: I also have about 20 HG on idle, thats about right, ive looked for vacuum leaks and haven't found any.
 

BMFB

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Re: Overboost..

Would i be better off just getting like a magniflow high flow cat. Like, would i loose any measurable power just replacing the none existent cat with a high flow one?
 

WyoSyclone

Active member
Re: Overboost..

You may be overthinking this one just a bit...
I guess the first question is what is your final boost target? The boost control on the stock trucks is proven as being inadequate... but, if your boost target is around 15 or a bit more the stock system will control it and do an OK job... not perfect, but OK.

You'll really just need to play with the boost control parameters in '59 to get it as flat as possible. I hope this makes sense :D
 

BMFB

Not to scale
Re: Overboost..

Well, at the time my boost target was 10 (just for the tuning and trying to be safe) but my final target is around 18, which is higher that what seems to be my minimum of 15ish. i am not sure how my system will take 18 PSI, if i will need alky or anything, but its where i would like to end up. If Im trying to go 18 and i can control down to 15, should i just leave it?
 

WyoSyclone

Active member
Re: Overboost..

Well, at the time my boost target was 10 (just for the tuning and trying to be safe) but my final target is around 18, which is higher that what seems to be my minimum of 15ish. i am not sure how my system will take 18 PSI, if i will need alky or anything, but its where i would like to end up. If Im trying to go 18 and i can control down to 15, should i just leave it?

I don't have any experience running without a cat... you should be able to add 5% back into WGDC and see what effect that has. The trick with the dang stock WG is getting a smooth boost response.... the wastegate is so marginal that it either undershoots or overshoots and results in a bumpy boost curve :(
 
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