Automobiles Forum banner
1 - 20 of 21 Posts

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #1 ·
hey, today i put a new vdo boost/vac gauge in my car, and i never paid that much attention to the old autometer boost gauge, but i (according to the vdo) can attain 12psi of boost in 2nd,3rd, and 4th, when revving out to 6k+. when in 5th and floored it hits 6psi and no more, but the higher the rpm the higher the boost goes,topping out at 12psi. this is kinda freaking me out since as far as i know, the audi computer and W/G spring are stock.
could the gauge be faulty? now I wish I'd paid a little more attention to the old gauge at high rpm.
 

·
Registered
Joined
·
6,305 Posts
Could be caused by a small tear in the wastegate diaphragm except it would be worse in 5th. In fifth is it pulling smoothly.
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #3 ·
i replaced the W/G diaphram soon after i got the turbo conversion complete, about 4,000 miles ago, so i don't think it's that.
 

·
Registered
Joined
·
2,351 Posts
If you have a stock ECU and a stock spring and you're getting 12 psi you have a problem in your boost control system...

Check:

Check operation of the WGFV
Check Lower Waste Gate Hose from Intake Manifold
Check Vacuum/Boost Hose from Intake Manifold to Engine Control Unit
Check Waste Gate Diaphragm
Check Waste Gate Valve for sticking or restricted movement
Check Waste Gate and Waste Gate Solenoid Hose connections and routing.

Also, I'm interested in why you're not experiencing fuel cutout? Did you alter anything in the ECU?

Steve
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #5 ·
well, the 034 unit maybe why i'm not experienceing fuel cut out :wink:
i have my mac 11 powered by a relay that is triggered by the ignition key.
it runs only ignition duties on my car.

as for the WGFV, i removed mine, one less thing to worry about.
the lower wastegate hose that pressurizes the lower half of the diaphram is new, but i'll double check it.

also, i did a couple of WOT runs in fifth, and it pulls nice and smooth, and good :p , very good 8)
 

·
Registered
Joined
·
3,280 Posts
what's your car/engine? i wish i had that problem! :bump: i'll be installing a boost controller tonight....just a bolt thru the cap.....hopefully i can crank it up some then.............

jeff
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #7 ·
check my car on my webpage, (hint, it's in my signature at the bottom of every post :wink: )
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #8 ·
ok, i checked the W/G diaphragm by putting a vac in the vent of the W/G housing and could pull nearly 30 inches of vaccuum with no leak.
if the wastegate is somehow sticking, how would i be able to tell. like i said earlier, when I'm at about 3k rpm and i floor it, the boost goes right to 6 psi and stays there til' about 5k, then slowly climbs until it tops out at 12psi at about 6k to redline. and it is consistently doing this, no jerking or abnormal boost spiking or dropping. i really wish i'd paid attention to the boost gauge more when i drove it before i got rid of the first gauge. usually I was paying attention to my tach and wether or not there were any cops around :p
plus, when i did my tuning i was paying attention to the laptop, not the gauge.
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #10 ·
ok, as far as i know, the spring, mac11 and all that stuff is stock. i have not messed with making it adjustable. the factory cover plate is still in the W/G cap. so i can't mess with it.
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #13 ·
ok, i took my W/G housing off and checked to see if it moves freely and it does, no problem. so i don't know what i'm dealing with here. you can see in my pics the wimpy lookin' gold colored spring is my stock one and the silver one is the 2bar. the 2 bar is considerably larger in diameter than the original, is the later model spring larger than the earlier? cause if i remember right i got one for an s4 thinkin it would be the same. it doesn't quite sit in the perch just right, but any of you think i might have a problem with that too? or what my boost increase might be caused by? :(
 

·
Administrator
Joined
·
201,871 Posts
It could be that the lower pressure line to the WG is leaking a little, and not cracking the WG enough, if it's the origional Audi 'cloth' wrapped line chances are it's seeping under pressure.
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #15 ·
nope, i replaced the manifold pressure line to the W/G housing with a new weatherhead heavy duty hoses. about 4000 miles ago. so anybody have a stock spring they'd be willing to measure or send to me for comparison, so i can find out if my spring is actually a stock one?
 

·
Administrator
Joined
·
201,871 Posts
I agree with Jim, looks bone stock, right down to the little green paint marks. Have you run the car with the upper chamber hose to the WGFV disconnected? That should result in ~6psi max, perhaps the lil wgfv is leaking air/not hooked up right?

Dunno man, keep at it :)
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #18 ·
derracuda said:
as for the WGFV, i removed mine, one less thing to worry about.
the lower wastegate hose that pressurizes the lower half of the diaphram is new, but i'll double check it.
ha, guys, i'm at a loss here too :)
also, i haven't installed the 2bar spring yet, i'm just gonna keep the stock one in there for now and make it adjustable.
 

·
Registered
Joined
·
2,692 Posts
derracuda said:
derracuda said:
as for the WGFV, i removed mine, one less thing to worry about.
the lower wastegate hose that pressurizes the lower half of the diaphram is new, but i'll double check it.
ha, guys, i'm at a loss here too :)
also, i haven't installed the 2bar spring yet, i'm just gonna keep the stock one in there for now and make it adjustable.
Just a thought.
Since you seem to be having boost creep, usually caused by an undersized wastegate (not the problem in this case) I'd drive the car with the spring removed from the WG and see what you get. There is a chance that, somehow, your wastegate dump into the downpipe is fouled up somehow, so that it can't vent enough exhaust gas at higher RPM. It's a long-shot I know....But testing without the spring will take another possibility out of the equasion.
Good luck :)
Mike
'88 VW "R22" 6psi on stock spring
 

·
Registered
Joined
·
17,178 Posts
Discussion Starter · #20 ·
well, i did just that, and only can acheive about 2-3 psi. no more and it makes my car sound all raspy (ugh). so i guess i'll have to live with my cars curse of high boost :D . when i make my header, i'm planning on just having the W/G dump strait out underneath for the wow effect, i guess i'll just have to wait and see how noisy it is :p
 
1 - 20 of 21 Posts
Top