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Old 12-07-2019, 06:23 PM
Strongbuilt1775 Strongbuilt1775 is offline
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Default LB7 boost pressure test noise

Hello, first post here on the forums. I am new to the diesel world and recently got my ‘02 LB7. Quick story, I went to step on it on the freeway the other day and it just felt like the truck wasn’t what it should be. Not a huge power loss but just didn’t feel like full power was there.

After researching online I decided to do the boost pressure test. After i hooked up the plug w/ fitting I began the pressure the line. Here’s where it gets weird, if i had the ball valve half open I can hear it loading the air and then air leaking out at the EGR valve. Now if i open the ball valve all the way it makes this very weird noise. I am no mechanic by any means so I came here to seek some help on this noise.

As for the EGR, do I take it off and clean it or once it leaks it is bad? Thank you for the help! Below is the video of the noise I am referring to .

https://youtu.be/Q0jGENOkNMw
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Old 12-08-2019, 09:55 AM
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Welcome aboard!

The 02-04 CA LB7 EGR's can normally be cleaned a few times before needing replacement. Much depends on how long they run dirty (longer means greater erosion). They can be fairly dirty before they trip any codes or cause running issues, so a check/clean should be part of normal maintenance if using any fueling-type or pressure-fooler power adders (timing only doesn't seem to accelerate fouling).

The noise you hear is either more air passing the EGR, or the wastegate (which will be equally fouled with increased fuel), or both, causing valve oscillation. How much air pressure were you using? Both should be cleaned regularly. Black smoke on acceleration and soot buildup at the tail pipe is a good indicator. More modern power adders tend to be a LOT cleaner than earlier, so you may consider that in the future. Avoid any devices or power levels that produce noticeable black/gray smoke or soot buildup. Rolling coal in SoCal can get you flagged pretty quick these days.
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Old 12-08-2019, 10:15 AM
Strongbuilt1775 Strongbuilt1775 is offline
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Thanks! I had my regulator set at 25 psi for the test. I was planning on deleting my EGR when I get efi live in the future. So for the time being I guess i will need to remove my EGR valve and wastegate and clean them. Just brake cleaner and a wire brush i would suppose? Any special instructions? Thanks again
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Old 12-08-2019, 10:39 AM
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I like a soak in kerosene (or #2 if no kerosene) to break up the soot, then minimal brake cleaner (which can damage seals/plastics with too much). Nothing special really, just get in and get dirty. A subscription to alldatadiy.com is invaluable for the procedures, assembly, and torque specs.

CA EGR deletes can be tricky. If the diag's are just disabled, it won't pass smog. The PID's must run or the test will fail before it begins. Most EFI Live scripts fail, so be choosy. Once de-rated prior to a test, run it hard at least a couple days to make sure all the diag's run, or it will fail. Always pre-test at the smog station, and they will usually tell you which diag's haven't ran.
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Old 12-08-2019, 05:07 PM
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Soaked the EGR in kerosene and cleaned off with brake cleaner. A lot of soot came off, let it dry and reinstalled everything, PITA by the way haha. Tried the boost test again and still leaks !!! So new EGR must be in the future.
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Old 12-08-2019, 07:39 PM
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If it's been fouled and leaking for a while, it may be eroded enough it won't seal. The valves are fairly durable, though. Before throwing in the cash, make sure air is actually leaking through the valve.
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Old 12-08-2019, 09:17 PM
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I’m not sure how long it’s been like that, I bought the truck a few months back. So when i pressurized the lines I heard the air so I pinpointed it to the EGR valve and when i put my finger over one of the three oval slots on the top of the valve i could tell the air was coming from there due to the noise difference it made.
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Old 12-08-2019, 09:32 PM
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That's probably it, then. Do you know what power mods were run before and how long, and what are you running now?
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Old 12-08-2019, 09:49 PM
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No power mods before older gentlemen I work with that I bought it off of. Since I’ve had the truck I put the MBRP 4” down pipe back exhaust on about a month ago and just put on the PPE boost valve this weekend.
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Old 12-08-2019, 10:25 PM
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That won't accelerate or exaggerate EGR fouling. Must be high miles or a LOT of idle time.
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Old 12-08-2019, 10:36 PM
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I’m guessing idle time cause she’s only got 112k on her. So since the new egr’s I’ve found online are 175+ should I just get block off plates?
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