Hi Guys,
I have been wrestling with this problem for two weeks now. Here is a short summary. Car was rock solid before with this exact setup.

Greddy ProfecII, Autometer boost gauge and GT800 package from EVOMS.

1) Two weeks ago, noticed a surge in the car on 91 octane.
Car was set to 17 lbs boost on low setting on EBC, but was boosting to 21.

2) My Autometer boost gauge seems to work as before (showing 21 lbs), the Profec however, seem to see 4.5 lbs less boost.

here is what I have done so far.

1) Both my Autometer gauage and Greddy seem to read 0 when I open the back (we are almost at sea level in San Diego).

2) I attached an air hose with boost gauge to the back of Greddy and at 30 lbs it read spot on, my air-compressor does not operate accurately below 25 lbs.

4) using a vacuum pump, I have tested the integrity of the boost lines. NO APPARENT LEAK.

3) We are checking the waste-gates on my 3071s and planning to install a manual boost gauge right before the input to Greddy.

I am about to buy anther Greddy Profec II to just eliminate that piece as well.

So all you Oracles help this near mortal here, any and all suggestions are most welcome.


Over-boosted and Frustrated.
-Arman

 

Not much advice, except why don't you use the factory boost valve? Are you changing boost with your gas type?

be careful until you figure it out, not worth blowing the engine.

 

Thanks for the advice, car is running Sunoco 104 GT blue at the moment for safety reasons. The setup was/is a pre-exisiting one and use I use the low and high setting for 91 and race fuel setting.

-Arman

 

changing the greddy is not the answer...
whats your set gain set up at?

to really see the pressure your car is doing why dont you run a durametric on it... then compare...

another thing to do... pressure test from the turbos... but you need a accurate gauge compressor... and pressure to 20 psi lets say... then have someone look at the greddy and see what it will read out...

also, are both auto meter and greddy tapped in at the same location?
Boost leak? did you do a boost leak from the turbos?

 

Check all pressure turbo pipes for leaks...But i bet vacuum hoses that goes to wastegates leak somewhere...Had the same problem and one of them was leaking...(at 996TT)...

 

>> We are about to find out. I am not sure, I need to follow the boost line from the ****pit to the bay as it is routed over the tranny.


Again Mark thank you for all your suggestions and useful tips.

-Arman

 

This is what my mechanic thinks too, however, what bothers me is that Greddy is seeing X and Autometer sees X+delta, no if Mark is correct and both are fed from the same source why the difference.

It is just weird.

 

Mark (or anyone with Greddy),
With a fully warmed engine my Greddy Shows -99 while my boost gauge shows -14 in.Hg. Is this normal?

 

at idle on vacuum it should show -.60 to -.67... so you probably have some boost or vacuum leaks... boost test from the turbos will show everything... assuming you do it right and diagnose the issue(s).

 

How about my boost gauge showing -13/14, is that one ok?

-Arman

 

I have no idea... btw who installed the kit? or did you buy the car that way...
I didnt know Evoms sold that kit with a greddy... Usually they offer it on the bigger motor build packages.. is this something you added afterwards?

 

I purchased the car as is, but it was motor work was done by Alex at Sharkwerks and the additional tuning by EVOMS itself. As a matter of fact I plan to send the car back to them for injector, fuel pump upgrade and if lucky a new tune.

BTW, thank you for all your suggestions.

-Arman

 

-13/-14 is that in bar or PSI?

 

I believe my gauge uses in.Hg which with the use of google unit conversion gives -6.39 PSI as Mark mentioned.

 

Ok them why don't you send the car to Alex to figure it out instead of having different people work on your car ? The more hands in your motor the worse it will be in the long run, and while your car is there you can do the rest of the work