94 f350 7.3l turbo diesel looses oil pressure as rpm increase

engine problem, and no engine told at all.
No year told now that is a hard ROW TO HOE. 1973 to 2017 outside asia. wow so hard to guess year no? crazy hard.
NO country told and that fact helps point to 10 engine used world wide.
Diesel engines but is it turbo charged.
NO DTC errors to tell? just PID = 8000 psi?
is idle RPM at spec?
leaking injectors or bad 2000 bar pump or RPM way too low.
GEN 9, 2007 first diesels, is my wild wild guess is this./

• Diesel:
• 1.8 L 4N13 turbo I4 (part Renault) CSR (I guess this)
• 2.0 L VW BWC turbo I4

get the service manual is best. for sure presssures
common rail solenoid Injectors?
some have pressure regulator, ? 2,000 bar ,says web searches.
29k PSI,

on the pump is this SCV (is modulated by PCM)(ECU)
the tank feed pump feeds this, SCV. my guess is this is bad,
Diesel Fuel Pump Pressure Regulator Suction Control SCV Metering Valve 294200-2960 For Mitsubishi Lancer 4N13 4N15 the rail end has pressure limited, that opens at 2400 bar.
if it leaks , pressures fall. but my guess is ok. here.

my guess is the 8000 psi, failure is real the sensor did no lie.
550- bar is too low. (using bar, pressure seen in Denso manuals 4N13)

see page 14 for they whole deal

https://www.service-engine.com.ua/webroot/pdf/MITSUBISHI%204N13,%204N14%20ENGINES.pdf

check for turbo failure, loose turbo hoses or cracked intercooler
at idle the amount of air is correct for the fuel setting but on rpm the fuel increases but the air increase is missing
run fault codes

2.9 to 3.9 bar at 3000 rpm is fairly general for the Nissan range including turbo diesel, though the pressure isn't listed for the td27 engine. I doubt it would be more or less than the others.
I notice one Nissan commercial vehicle engine where 3.0 bar at 2000 rpm is specified.

The oil pressure test should be carried out at normal operating temperature.

Have you checked the PCV system?? If its stuck in the closed position then you will lack power and turbo boost. A vehicle needs 3 things to make it run proper; FUEL,FIRE and AIR. Try that and see if it helps.

Oil pressure drop after reaching operating temp is normally caused by worn main bearings (depending on mileage).Worn bearings will allow pressure drop at idle and increase when accelerated above idle.

The turbo charger has more to do with rpms than road speed.The turbo uses exhaust gas leaving the engine to push more fresh air into the engine thus creating higher compression and more horse power.You should feel some boost above 1500 rpms if everything is working properly.If not then you should have the system checked by a dealer or a good diesel shop.Good Luck!

This seems pretty normal. So long as the pressure does not fall while driving, you're good.
When Idling there is very little stress on the engine, and it requires little oil pressure to maintain.
Additionally, the pressure is directly related to the rpm of the engine as the oil pump is driven by the engine. As the rpm increase, so does the pressure. The pressure should be stable at a given rpm.

The pressure on the high side is good. On the low side is adequate (idle). You did not say how many miles, but the only way to change this is to rebuild the engine with new bearings and seals. I don't think that's somthing you want to do. Sounds fine for now. Leave it alone.
Don't fall for a new oil pump. That is very rarely the issue.

That is normal. As you accelerate and rpm's increase the oil pump rpm increases. I think the oil pump runs 1 to 1 or 2 to 1 with the crankshaft rpm. Check the oil and inspect for any visual leaks if the gauge does not operate like that consistently. If it is intermittent or it just started acting that way, the sender my be bad. Other than that any Chevy Dealer will say that is normal.

You probably have a high mileage engine. Change the oil and go to a heavier oil viscosity and use a quality oil filter. This should help a little. If the engine has many miles on it this is about all you can do to boost the oil pressure. I don't know what engine you have. So you have one of two possibles here. A 302, a 351. A high mileage engine in either of these two engine configurations should have at least 20 pounds pressure at an idle and should rise as the engine rpm's increase. Good luck.

No diesel I have ever owned will heat up to operating temp while idling. I have had semi's and dump truck and a Dodge with a Cummings turbo diesel. If you don't idle a diesel up to around 1200 rpm while sitting the combustion chamber temperature will drop because the diesel does not ignite fully at low rpm. You may also notice after an extended period of idling 1/2 hour or more that when you pull away the exhaust will be whitish blue because of the unburnt diesel fuel sitting on top of the rings. Also extended low idle will wash down the cylinder walls with unburnt diesel and remove the oil from lubricating the cylinders and rings. Hope this helps you understand why your diesel won't heat up while idling. Mike