Positive air shutdown installation - Ford F150 Diesel Forum
 
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post #1 of 6 (permalink) Old 07-01-2019, 07:32 PM Thread Starter
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Question Positive air shutdown installation

Good afternoon, new member here. I have had my f150 for a few months now. I need to install a PAS for work. I am wondering if anyone else has had to install one on the 3.0 yet and what your set up is like. I doubt anyone has already had a runaway but if you did can you share what happened?

Coming from the 6.7 there was two options 1) use the throttle plate with an aftermarket controller 2) install the PAS valve on the air intake. On the 3.0 there isnt any space to after the aftermarket PAS valve.

According to the Ford publication for the 3.0:
The throttle body is mounted on the intake
manifold and houses a servo- controlled flap, called
the throttle blade. The throttle body assembly has
the following functions:
Meters the flow of air into the engine, under
all operating conditions
Prevents serious engine judder when the
engine is stopped
Throttling of the intake air during the DPF
regeneration process
The throttle blade is actuated by a DC motor.
Actuation is performed via Pulse Width Modulation
(PWM), which is controlled by the PCM/ECM. The
position of the throttle blade is monitored by a
Throttle Position (TP) sensor assembly. This sensor
is actually two sensors, each of which is a
potentiometer, in a single housing. The output
signals are analog voltage signals and are mirror
images of each other going in opposite directions.
The throttle blade closes on shutdown and then
remains closed for about 2 seconds before
reopening.


THANKS!
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post #2 of 6 (permalink) Old 07-01-2019, 07:54 PM Thread Starter
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I realized there are most likely lots of members who never even heard of this. For your enjoyment watch this youtube video. It shows what happens when an uncontrolled amount of fuel is sent into your air intake. I had to include a space in the link as my post count is too low.

youtu be.com/watch?v=BYSXCHFA7MM
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post #3 of 6 (permalink) Old 07-01-2019, 09:38 PM
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Wow, what do you do that requires this? Just curious...

2018 Ford F-150 King Ranch 3.0L Power Stroke 4x4 | Icon 2.5 Front & 2.0 Rear, Toyo AT II 295/60R20, 3" ProComp Rear Block, S&B Dry CAI, LineX & BakFlip MX4, BuiltRight Seat Release | ForScan Mods: Disable Double Honk, 2x Panic, DPF Full %, Digital Temps Above Gauges, A.S.S Disabled
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post #4 of 6 (permalink) Old 07-01-2019, 10:03 PM Thread Starter
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Quote:
Originally Posted by wreedsvt View Post
Wow, what do you do that requires this? Just curious...
I have to drive to oilfield sites, among other places....

To gain access to oilfield sites it is usually mandatory to have a way to shut down the engine if combustible gases become mixed in the environment. A positive air shutoff is needed for anyone with a diesel engine that may come in contact with natural gas, propane, or any other flammable gasses. A small leak of flammable gas is likely to cause a diesel engine to "run away", causing catastrophic damage to the engine, and surrounding area as it explodes. If it explodes on a site with hazardous atmosphere like a refinery, you would most likely make the 6 o'clock news. Diesel engines will run on any fuel available even when the key is removed. Once a diesel engine gets a supply of flammable gas in the air, it will run indefinitely or to the point of catastrophic failure. The only way to prevent and stop this is to shut off the air supply to the engine, starving it of air born fuel.

However in the crappy link I posted to youtube above, none of the vehicles appear to be on oilfield sites but they still had runaways. This is because diesels can also run on their own oil. For example, if your turbo started leaking in your driveway the motor would rev past the red line until it was starved of oil and it seized up solid and/or had its own coming out party.
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post #5 of 6 (permalink) Old 07-01-2019, 10:13 PM
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Yes I completely get and know what a run away diesel is, interesting, I will ask Dorian (local PS expert in Houston) about this....

2018 Ford F-150 King Ranch 3.0L Power Stroke 4x4 | Icon 2.5 Front & 2.0 Rear, Toyo AT II 295/60R20, 3" ProComp Rear Block, S&B Dry CAI, LineX & BakFlip MX4, BuiltRight Seat Release | ForScan Mods: Disable Double Honk, 2x Panic, DPF Full %, Digital Temps Above Gauges, A.S.S Disabled
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post #6 of 6 (permalink) Old 07-01-2019, 10:25 PM Thread Starter
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Quote:
Originally Posted by wreedsvt View Post
Yes I completely get and know what a run away diesel is, interesting, I will ask Dorian (local PS expert in Houston) about this....

Haha okay sorry for the long explanation some people just dont get it. I was just in Houston last week, saw a dark colored leveled 3.0 deleted while driving down the road. They sure sound good when they get done!
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