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My 2003 f150 5.4 runs ruff then stalls when cam sensor is…

Customer Question
My 2003 f150 5.4...

My 2003 f150 5.4 runs ruff then stalls when cam sensor is plugged in. but if I unplug it the truck runs great. it is a new sensor also

Mechanic's Assistant: Is the check engine light on? Does the car stall at idle or when driving?

When its plugged in

Mechanic's Assistant: Are you fixing your F150 yourself? What have you tried so far?

Yes myself new sensor and alternator

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

That's it

Submitted: 4 months ago.Category: Ford
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Answered in 8 minutes by:
12/10/2017
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago
David Craig
David Craig, Auto Mechanic
Category: Ford
Satisfied Customers: 5,179
Experience: owner/mechanic at 3D Automotive
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Hi my name is ***** ***** I'll be more than happy to assist you. Please allow me a few minutes to review your information. Thank you

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

what are the fault codes, please?

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Customer reply replied 4 months ago
P0340 the only code
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

ok, standby please

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

how many wires on the cam sensor 2 or 4?

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Customer reply replied 4 months ago
2 wire I checked continuity from the plug to the pcm and both are good
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

check the resistance of the sensor

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Customer reply replied 4 months ago
the sensor is good I checked the sensor. and tried 2 new ones that I had
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

what s the resistance?

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Customer reply replied 4 months ago
both sensors are new. and are good
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

not what i asked

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Customer reply replied 4 months ago
299.8 ohms
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

ok, thanks.

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

now, even though the wires from the sensors connector checked good for continuity, please check each wire for a high resistance short.

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

hows it going?

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

do you still need assistance?

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Customer reply replied 4 months ago
checked both wires and both have between .1 and .2 ohms
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

if both wires read that then they are shorted to ground. are you sure you had the other end of those wires disconnected?

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Customer reply replied 4 months ago
both these wires were tested from the cam sensor plug to the harness bulkhead to the pcm. and it was unbolted from the pcm
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

then those wires are shorted to ground somewhere

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Customer reply replied 4 months ago
but I can take my volt meter and on the cam plug green wire (signal wire) probe it at the plug with my red lead and ground my black lead to battery ground and have no conntinuity
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

ok, that checking the wire for a short to ground. no continuity is good. are you doing the same for the other wires?

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Customer reply replied 4 months ago
this is just a two wire plug. and the ground wire probed to the plug and the battery ground I have continuity.
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

as you should.

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Customer reply replied 4 months ago
where do you think I should go from here
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

so we have good continuity from the sensor to the ECM and no short to ground on the signal wire

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

standby please

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

so it does start with the sensor plugged in but it runs rough correct?

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Customer reply replied 4 months ago
with the sensor plugged in it does start runs fine for a half a minute then surges and stalls. if I unplug the censor the truck runs great.
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

ok. standby

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Customer reply replied 4 months ago
I will try this tomorrow and let you know. thanks
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

ok, thanks. Ill be on most of the day

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Customer reply replied 4 months ago
is this link asking me to disconnect pcm harness and check cam signal wire from the harness to the battery negative with key on
Customer reply replied 4 months ago
if that's the case I have no voltage at the harness
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

standby please

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Customer reply replied 4 months ago
on DR9 I got 2 ohms per wire. not too sure exactly what their asking for DR10
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

standby

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

signal return is the ground wire

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Customer reply replied 4 months ago
also can I drive the truck with the cam sensor wire unplugged
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

i wouldn't. that will throw a lot more things out of whack and the computer can only compensate so much

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Customer reply replied 4 months ago
on DR11 do they mean when I plug the pcm back in. check the resistance on the can sensor plug end with both my red and black leads on the female terminals of the plug. if so I'm getting 4.650 ohms
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

standby please

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

it says to read across the cam sensor connector pins with the pcm connected.

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

is that 4.650 ohms or k ohms or m ohms?

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Customer reply replied 4 months ago
4.60 M ohms nothing on k ohms or ohms
Customer reply replied 4 months ago
4.650 M ohms nothing on K ohms or ohms
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

ok, then that's ok.

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Customer reply replied 4 months ago
I still have to test the next step but wanted let you know I took out the cam sensor plugged it into the harness started the truck. waived a wrench back and forth over the sensor and the truck ran rough and died out
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

then the sensor is either bad or the trigger wheel is dirty/oily

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Customer reply replied 4 months ago
trigger wheel do you mean cam gear
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

yes

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

if its stalling/running rough when picking up a target its either the sensor or the computer

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Customer reply replied 4 months ago
we know the cam sensor ( sensors ) are good we already established this. what should it be doing when Its picking up a target way way I'm doing it here. also you think it probably the computer then
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

its an inductive sensor picking up the target and producing an ac voltage to let the computer know the firing sequence of the injectors and coils

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Customer reply replied 4 months ago
ok so should it be stalling out when I waive a wrench over the sensor
Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

if it not at a constant pulse of the same speed then it will run rough or stall

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Ford Mechanic: David Craig, Auto Mechanic replied 4 months ago

hows it going?

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