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Old 07-07-2020, 11:01 PM   #1
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brand new 6.0 with low fuel pressure (<30psi at WOT)...results

by installing the regulated return, we were able to compare the pressures at the fuel filter cap (edge pressure sensor) and the Fuelab fuel regulator.
it's about a -7psi difference from filter to regulator...which doesn't bode well for the pressures noted below.

Posted this on FTE about a month ago with updates:

Would really appreciate the forums input on a issue we're having with a brand new engine (DD) with maybe 6,000 miles on it.
This is not a daily driver and is driven infrequently...this is a camping vehicle.

We got the vehicle - E350 - back in fall of 2019 with the new engine and it was great.
Fast forward a few months and we started experiencing an intermittent bumpy idle and sluggish acceleration + more than normal black smoke from a stop.

Sluggish means that it feels like there's no turbo until ~2,000 rpms and then boom...takes off.
There's also a noticeable difference merging onto the freeway...
1. during bumpy idle, the transmission will downshift in order to get up to speed..
2. during normal operation, the vehicle will accelerate more smoothly and quickly without downshifting

Over winter 2019-2020, while repairing the HVAC system, we discovered the vacuum line was disconnected from the remote reservoir and thought that the aforementioned issues were from a vacuum leak....we fixed the leak.

About 2? months ago, the bumpy idle returned (or at least it seemed like it did) and we decided to pull the codes from the Edge CTS2, which showed a P0284 code.
We took it to the shop that did all of the engine work and they determined to replace the #8 injector.
The very evening we got the van back, we went for a ~70-80 mile test drive.
Everything seemed normal until the return trip and the offramp to our house...the bumpy idle was back and sluggish acceleration + more black smoke from a stop (and P0284 code).
Returned the van to the shop and they said that the compression came back good...and unable to recreate the issues.
Replaced the FICM (BPD) with a known good FICM and we got the van back.

Now to the question - how much would low fuel pressure affect injector lifespan?
Or cause injectors to fail?

Here are the reading from the Edge CTS2 with a pressure sender on the fuel filter cap in the past week.
low = 29psi at WOT
and ~48 psi at idle

We changed the HFCM last night and fuel pressures are:
low = 35 psi WOT
and ~53-54 psi at idle.

We had installed the blue spring kit on the old engine.
With these pressures, does it seem like a blue spring kit was installed with the new engine?

If a blue spring kit wasn't installed and these fuel pressures have been ongoing for ~6,000 miles, what might be the outcome?

What do we need to do?

The engine is not like it was when the engine was new about 9 months ago.

2006 E350 4x4 with 6.0 (5r110+Atlas TC+D60's w/ 4.11 gears on 34" tires) with the same specs as the KDD stage 1 -
It has custom tuning from using a SCT X4.
Diesel additive was added to every half tank of gas (46 gallon tank) - Amsoil all-in-one or RedLine 85+
5w40 synthetic oil once the engine was broken in...15w40 during break in.
Diesel always purchased from Chevron/Shell/Costso.


OK. So we fab'd a custom regulated return using banjo-to-AN fittings on the back of the heads, 6AN PTFE lines to a Fuelab 51502 that returns to the HFCM.
And gutted everything under the fuel pressure orifice plate...installed a 16mm x 1.5 to 1/8 npt and fuel pressure sensor in the return line port.
[the next step is to fab PTFE lines from the tank to the HFCM and the HFCM to the engine >>> 8AN supply and 6AN return]
Idle pressure is 59.0psi and WOT is 56.5psi...
And still have the bumpy idle, significant black smoke from a stop and sluggish acceleration.
It behaves this way for 90% of the time...and is not how the engine behaved when new.
The reason we say 90% of the time, we just drove two miles after letting the engine sit for ~20 minutes (EOT on startup was 188...IAT was's a mid-90's afternoon here).
The engine started the 2-mile trip with bumpy idle, etc., etc. and when we pulled into the driveway, the engine was idling normal - no bumpiness whatsoever.
Checked the codes and only a P0113 - intake air circuit high
The Edge Insight cts3 shows IAT at slightly above ambient unsure if an air sensor is failing?!?

Any ideas?
If we drove this engine for ~6,000 miles with 28-45 psi, what should we expect?
Appreciate the help.


Here's what the exhaust looks like today July 7, 2020
while driving:

and while idling at the end of our 25 mile round trip road test:

The entire playlist =

2006 E350 4x4 SMB: 6.0L-5R110-Atlas-D60-D60-yada-yada-yada
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Old 07-07-2020, 11:12 PM   #2
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That's low enough to trash the injectors. But I don't know how quick that damage can happen. You're the first person I know who was able to track their own fuel pressure. Usually I'd only get it after it stalled or wouldn't start, so it could have suffered low pressure for longer than you did.

Also, just to help rule out contributing causes, what's your FICM voltage at worst case (hot, idling with headlights and A/C on, including rear a/c if you have it)? What about Injection Control Pressure at idle, and ICP duty cycle? What about turbo VGT duty cycle when you have those rough running or black smoke conditions?

FYI your videos are set to private.

2000 E450 dually V10 wagon
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Old 07-08-2020, 07:07 AM   #3
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Thanks for the youtube reminder...haven't uploaded in years.

Here's a video of the engine monitor while idling in the Lowes parking lot...the halfway point of our road test yesterday.
The idle at this point was what we term "normal" with load changing by 1-2% 26% to 28%).
A video showing the bumpy idle from the previous evening with load changing 7-8% (48% to 56%)

FICM changes to a low of 48 volts during a drive.
This had a 6-phase bulletproofdiesel FICM on it and the shop swapped it for another FICM.
We're not driving this until the shop lets us know how to fix it, so the headlights+A/C test will have to wait.
2006 E350 4x4 SMB: 6.0L-5R110-Atlas-D60-D60-yada-yada-yada
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Old 07-08-2020, 09:01 AM   #4
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Those number all look really good. Including FICM. If it was suspect we'd see at least a little fluctuation.

I think next step is a cylinder contribution test with graphing. Relative balance should be done first to rule out compression issues (and then again when it's hot), but this is a reliable way to see if an injector(s) is bad. But if the balance graph is random while you're having the rough idle, it's being caused by something else.
2000 E450 dually V10 wagon
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Old 07-10-2020, 04:43 AM   #5
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Quick question from THE dumbest guy when it comes to diesel engines regarding the problematic FICM's---would it be beneficial to have a small battery and/or capacitor, almost like a battery back-up system for computers etc feeding that device to lessen any low voltages it might see?

At minimum I'd want to monitor via an accurate voltage meter or gauge on the charging system so any dips in that voltage would be easily determined.

Again I'm completely dumb about diesel engines so pardon me if I'm dumber than I think.
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