[96GMC6.5L]

Is there a way to check whether or not your boost gauge is accurate. If so I would really like to know, because it seems kind of low for me to not even be able to touch 5psi under WOT for 15 seconds.

Thanks, Jacob

 

[Dave12]

5 psi does seem low. Any restrictions in the tubing from the intake to the gauge? Pinched or twisted? I would think you should be seeing at least 8.

Dave

 

[96GMC6.5L]

I don't think there are any twistings or kinks, there isn't really any place for it to twist or kink. I don't know.

Thanks, Jacob

 

[Dave12]

How about those little compression ferrules (olives). I don't know if it's possible but if you tightened the fittings too much, could you have pinched the line?

I'm just trying to have you eliminate the obvious to see if that is what's causing your low boost reading.

Dave

 

[96GMC6.5L]

I think you would have to tighten those quite a bit to pinch the line. That thin line is pretty stiff. I don't know they have to be fairly tight so that they don't leak.

Jacob

 

[teroma25]

If you tighten it too much you will bust the fitting long before you will kink the line.

 

[Turbine Doc]

Get a combo vac/press test gauge usually good for 15 psi & 30" vac about $20 most part houses; add a long hose so you can run it into the cab great for testing vac, fuel lift press, and boost verification.

 

[96GMC6.5L]

I don't think that is the problem. I tightened it, but not that much. Honestly the more I look at it the more I think it is the vac system. At idle my wastegate is still down, rather than the rod sucked into the canister and having the wastgate parallel to the bracket the canister is mounted on. If i wire the wastegate shut I should be able to find my problem real quick, whether it is my gauge, or the vac system. Is this a good way to troubleshoot?

Thanks, Jacob

 

[Turbine Doc]

Simple way to TS it yes, don't get greedy though with "found power" and keep the WG wired shut, use it for problem isolation then unwire it until you can fix it properly, have you been through the low vacuum/low boost troubleshooting FAQ threads?

 

[96GMC6.5L]

I did wire it shut, and still barely hit 5psi. I am starting to think that the exhaust is not pushing out fast enough, or something else is seriously screwed up. Any thoughts?

Thanks, Jacob

 

[Dan Hunter]

I'd want to know of the soot trap is full (add mileage to your sig maybe) and restricting flow though in general the factory exhaust in inexcusably restrictive and a great place to spend your money. As a minimum, putting a 3" downtube on your exhaust will free up the flow and likely reduce your EGT.

 

[96GMC6.5L]

You think the cat may be plugged up. The truck seems to run fine, though. Just seriously low boost. I dont' know what is up with this.

Thanks, Jacob