Recommended readings - Temperatures and Pressures

Edit (since the excel format is no longer supported)
https://www.ford-trucks.com/forums/a...0&d=1487990249





Also
VGT % duty cycle:
low idle......73%
high idle.....43%
cruise........55%
light accel ..67%
hard accel ..38%
coast.........57%

A high % means the vanes are commanded to a closed state.
85% vgt - vanes fully closed (trying to accelerate the exhaust flow to develop more boost)
A low % means the vanes are commanded to an open state.
15% vgt - vanes fully open

The VGT control valve is commanded by the PCM, based on engine speed (CKP sensor) and load (calculated value based on MFDES (Mass Fuel Desired) at a specified RPM). The PCM uses EP (Exhaust Pressure) to act as a closed loop control for the VGT and to monitor its performance.

When diagnosing a low boost concern, verify that there is no other concern that would cause low power. Since boost is created by the heat of expansion, anything that can cause low power will create low boost (ex. injectors, EGR issues/sticking valve/leaks, exhaust leaks, fuel pressure and quality, etc.).

Before replacing a turbo for low boost all other systems must be tested. Verify that MAP, BARO, EP PIDs are within 1.5 PSI with Key On Engine Off (KOEO).

More "low boost" troubleshooting:
EGR valves not fully closing which can cause these symptoms - heavy smoke, no power and typically the engine sound is muted; muffled and lacking that crisp combustion sound. A fully closed EGR valve will have a sensor voltage around .6 volts. If the valve is hung up and not fully closed it will not set a code until the voltage is 1.2 volts with the valve commanded closed. A stuck valve will bleed off exhaust back pressure which the turbocharger needs to speed up and build boost. Second, the open valve at low RPM chokes the engine with recirculated exhaust gasses which replace the air needed for combustion. THis causes the muffled engine sound and heavy black smoke. Often, the valve will stuck open more and the smoke will sometimes become gray.



and ...
https://www.ford-trucks.com/forums/1...d-voltage.html

 

More Info: Tranny Temp
As for the "Factory" transmission temp gauge, it is a glorified "idiot" light as its response is severely dampened. The panel gauge will show the temp as fully warmed up at 50 *F. Between 100-220F the needle will remain in the same position on the gauge. At 230F it will move up slightly to the middle of the normal range. At 250F it will move to Yellow. The gage moves to red at 280. This is supported on page 36 of the OBDII Theory and Operations manual. The tow/haul light will flash at 275.
Over 220 is really too hot for continuous service IMO - most likely something is not right when you see temps continuously this high. Never exceed 250 for more than 30 minutes for reasons below.
Mark Kovalsky (former Ford tranny engineer) says the fluid can get to 300 for a SHORT time w/o any seal damage (however a measured temp of 250 could actually mean that some areas and parts may already be as high as 300 - normal tranny fluid is good to 300 or so, but your tranny isn't!).

Also: Fuel Pressure
Ford does state that you definitely should not let your fuel pressure get below 45 psig - ever (even at WOT). They also say that 75 psig is the upper limit based on o-ring integrity in the injectors. Generally the right side injectors (passenger side) are the first to fail from lack of fuel pressure. Fuel MUST act as a buffer for the injector plunger. The suction pressure loss to the HFCM should be no more than 6 inches of vacuum.

Also: Coolant Temp
Some say fan kicks on at 210, some say 215, others say 220. Full explanation: Engine temperature is not the only parameter that the PCM monitors to determine cooling fan operation. This is the reason that you will see some variation in engine temperature as it correlates to fan operation. The operation/description of the FSS (Fan Speed Sensor) from the PC/ED manual has a fairly good explanation as to how the system "thinks". This is not your traditional engine hits temp X and the fan clutch locks up. The fan speed sensor is a Hall-Effect sensor integral to the vistronic drive fan (VDF). The powertrain control module (PCM) will monitor sensor inputs and control the VDF speed based upon engine coolant temperature (ECT), transmission fluid temperature (TFT) and intake air temperature (IAT) requirements. When an increase in fan speed for vehicle cooling is requested, the PCM will monitor the FSS signal and output the required pulse width modulated (PWM) signal to a fluid port valve within the VDF. Engine begins to defuel at 221 deg. The thermostat begins to open at about 190*F to 195*F and is not fully open until about 215*F to 219*F..

Also: Oil Temperature
Usually 5-15 deg above coolant temp. Engine begins to defuel at 253 *F oil temp (PC/ED manual). You should not exceed the ECT by more than 15 degrees.

So - The readings are based somewhat on opinions, somewhat on Ford values. People COULD argue that 220 and 230 are too conservative as alarm temps for the transmission. I couldn't really disagree too much, but I will say that for many transmissions, these alarm values are good. Most folks I talk to say their transmission runs way cooler than these alarm temps. IMO alarms should be set to inform you that something is not normal BEFORE you get into a danger zone. Also, some people with tuners and studs say 1400 - 1500 EGT MAY be OK for VERY SHORT bursts - I wouldn't want to do it. Lastly, BOOST values depend heavily on aftermarket mods like studs, turbo and tuners. It is really very hard to define a set of readings that apply to everyone. I know some people running at 40 psig boost w/ studs though and they do not seem to be worried. Even with studs, this would make me nervous.

 

Also -

The minimum engine oil pressure (low pressure oil) specifications are 82.7 kPa (12 psi) at 700 rpm, 165.5 kPa (24 psi) at 1,200 rpm and 310.3 kPa (45 psi) at 1,800 rpm with the engine at operating temperature. Low or no pressure could be caused by the oil pressure regulator, gerotor oil pump or an internal lube oil pressure leak. The engine will not start until the PCM reads 500 psi from the ICP (High Pressure Oil). The HPO pressure will range from 625 psi at idle and 4045 max psi with full engine load. a fast idle with no load will be about 1450 psi. This can be checked via the ICP sensor port.

The oil pressure sensor is just a switch that sends a signal to the instrument panel gauge. It closes a circuit to ground when the oil pressure reaches 5-7 psig. When the pressure is above 7 psig, the gauge will read normal. When it drops below 6 psig, it will read zero. The info from the switch does not feed back to the PCM in any way. The oil pressure regulator opens at pressure of 75 psig to send flow back to the pump suction.

Degas cap rated for 12 - 18 psig. Over 18 psig indicates possible headgasket leak.

For the EGT POST TURBO - this is based on cooling down after a heavy engine load before shutting the engine down (heat saturation on the turbo is the issue): Some people say that you should run the engine unloaded until post turbo EGT drops to 400 deg F .... then shutdown. Some people say the value is 450. You definitely should not TOW HEAVY and just pull into a fuel statiuon or motel immediately off the highway and shutdown.
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Bismic,

THANK YOU VERY MUCH !!!!!!!!!!! YOU ARE THE MAN

 

What would you think about removing the oil pressure switch and replacing it with a real sending unit to feed another gauge? Does the switch sense before or after the filter? I have a filter cap with a 1/4" port on it. I;m sensing temp there now but i could read pressure there instead but it won't tell me post filter values. Thoughts?

 

Thanks alot bismic!

 

IIRC, the oil pressure is after the oil filter and before the turbo feed.

Page 25: Lubrication System

Page 22: Lubrication System

I don't see why you couldn't replace this switch with a proper sending unit and connect it to a real gauge. The PCM does not see the info from the oil pressure switch at all.

 

Another great write up Mark..thank you!

 

Mark,

Excellent info. Would like to give you a rep but FTE says to spread the love.

 

Ditto on that Cowboy

 

Thanks again Mark,I too must wait to rep you.

 

10-4 Now that is great info !!!! I'll have to copy that.

 

Brilliant info as always from you Mark. Well done and thank you.

I've been considering doing this too. I'm wondering if the factory gauge will accept and display the signal from a proper pressure sender unit? Anyone tried it? What sender unit to use?

 

I still can't rep but I can say thank you for again being a great asset to FTE
Thanks bro,

 

Thanks for the write-up but I have a question about the 15 deg ECT/EOT. My truck runs about 8-10 degrees aroud town, 12+ degrees at 75 mph freeway and it can exceed 15 when I go up into the mountains or tow. I live out in the sticks so I always drive it more than 20 minutes before I get these readings. Dose this mean I am getting close to needing oilcooler service?

I am bothered by this because when I tow I go about 2000 miles round trip and I would hate to have problems when on the road.