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Old 04-07-2021, 02:53 PM   #1
Join Date: Sep 2015
Posts: 32
Low power, low boost, high EGTs

Hey gang,

I've been on a slow quest to improve reliability and replace/upgrade much of my 2005 E350 6.0 (165k).

I've been starting with fuel delivery and electronics; working my way through Alternator, FICM, batteries, etc. Seem to have sorted rough start, improved cold performance and other common issues tied to that.

Most other 'common 6.0' issues have been replaced/repaired/or ruled out.

These days, my challenge is low power (relative to this van's historical), high EGT's (8500-9000 at cruise, even low grade gets me to 10500 quickly), and low boost (6lbs or less). Now... I don't entirely trust my boost gauge and will verify it's reading with a scan tool soon.

I suspected turbo or intake leak and decided to put new turbo and intake elbows on. It was time to replace turbo anyway.

No change.

I did have a mechanic do some troubleshooting (pretty familiar with 6.0) and he checked Exhaust Back Pressure, which appeared to be quite high at 50psi. His theory is plugged catalytic convertor. I have no codes. This is interesting to me because I had not thought of this (would have expected a code)... and it also might explain where I get almost zero audible turbo whine--and I remember having it on this van. Plugged Cat might explain high EGT, low boost... and therefore low power, right?

So... two questions:

- this sound like a viable theory? If yes, who do you like to buy new Cats from? Should I go ahead and do Cat-back exhaust at the same time?
- mechanic also found a decent hole in the Downpipe that I somehow missed? Where can I source a replacement downpipe for the Van? I can't seem to find anywhere. Do you have to go used?

Thanks all, you are an unbelievable resource!

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Old 04-07-2021, 04:28 PM   #2
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Maybe an entire 4" Diamond eye system for $300ish

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Conversion in process. Lol
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Old 04-07-2021, 05:24 PM   #3
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Location: Eugene, Oregon
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You could park it in certain areas and someone will remove the CAT for you....but all joking aside you can remove it pretty easily yourself and replace it with a straight pipe and see if that fixes it. Then you'll have a decision to make about what to replace it with. It won't throw any codes with it off.
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Old 04-07-2021, 08:17 PM   #4
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Yup. 50 psi is way higher than you should ever have post-turbo.

Go ahead and just yank it. It barely does anything on a diesel, especially one that's working right. But you'll still need to find the original reason why it fouled.
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Old 04-08-2021, 09:42 AM   #5
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Thanks guys,

That helps. I'm in Cal, so there's that for visual inspection I need to consider. Regardless I'll remove the cat and check performance.
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Old 04-14-2021, 11:09 AM   #6
Join Date: Sep 2015
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Has anyone found a source online for a 'Catalytic Converter Test Pipe' or a Downpipe for Vans? I haven't found either in the right diameter for the 6.0 van exhaust. I've not been able to source raw exhaust pipe yet either--but might just have to roam further for that. I'd rather find a Test Pipe so can keep the visuals lining up for California inspections. Anyone had luck?
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Old 04-14-2021, 12:55 PM   #7
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exhaust pipe +elbows +stuff =

a shop we used made a custom downpipe with elbows and pipe...and it's okay (rubs a bit on the engine cover). i think the downpipe is 3.5-inches?

a quality exhaust shop should easily be able to fabricate a custom exhaust, including adding flanges for replaceable items that you don't want welded in place.
if they can bend tubing, they can upgrade the pipe size to improve airflow.

2006 E350 4x4 SMB: 6.0L-5R110-Atlas-D60-D60-yada-yada-yada
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Old 04-15-2021, 09:12 AM   #8
Join Date: Sep 2015
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Thank you! The photos help and Summit had exactly what I needed and shipped it blazingly fast. I'm going to attempt this myself and try to weld the downpipe. We shall see... Appreciate everyone's help! I'll report back if I have improved performance.

And Digg255, unless I'm confused with the forum format--please delete your post from my thread--I'm uninterested in your recent issues and can't find any relevance to this thread. Thanks!

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