P0340 low power

Phillip Diagnostician Alaska Posted   Latest  
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Driveability
2011 Ford Explorer XLT 3.5L (8) 6-spd (6F55) — 1FMHK8D80BGA33095
P0340 — Camshaft Position Sensor "A" Circuit Bank 1 or Single Sensor
Poor Power Under Load

So I have the vehicle mentioned above. Originally The vehicle came in for code P0340. I was able to verify I had zero signal output on the B1/S1 CMP via scan tool pid’s and labscope. I put a new Ford sensor in it and no signal. So I gained access to the ECM and scoped all 4 sensors and only the B1/S1 had no signal. I was able to swap a known good sensor with it and still didn't have a signal. The harness was long enough I was able swap B1/S1 connector with B1/S2 connector. look at that B1/S1 connector would output a signal on the B1/S2 CMP. Okay I must have a mechanical problem. To make a long story short I removed both bank valve covers and ….nothing looked bad. Took a feeler gauge and they were all damn near the same distance. (I don’t remember the actual number) At that point I was like WTF. So I re did all my test again like 3-4 times. One the last time I did my connector swap I put B1/S2 connector on B1/S1 CMP and I had a signal. So then I thought to myself...You idiot you didn’t do a pin drag test. I wiggled B1/S1 connector and hey had a good signal.(Keep in mind at this point I had valve covers & intake plenum off so I was only doing a cranking test) So I replaced the B1/S1 connector pins and code didn’t return. That was 1 week ago.

So the vehicle is back with same code. This time the sensor would be picked up by the ECM intermittently. This was verified via scan tool. So again I checked the signal at B1/S1 CMP connector. I had a signal running the vehicle at Idle. But when I snapped throttle it I got the screen shot. I checked with B2/S2 sensor and I don’t have the same problem. (I did wiggle my back probes and actually swapped from the red channel to yellow to just rule out tool problems) No I am at a lose and I hope someone can look at the wave form I provided and maybe tell me what I am not seeing. I know when the signal is going crazy is when the sensor signal on the scan tool drops out. I did also put dielectric grease on the connector right before writing this and that did nothing.

Please note the last data capture I had the B1/S1 on the blue channel & B2/S2 on the yellow channel.

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Thomas Technician
Virginia
Thomas Default
 

From what I can see is B1S1 and B2S1 share the same return circuit they. VRS RTN comes out on pin 44at PCM on GY-OG wire then they splice off at splice S151 which is in the harness right about at the Y for the PCM connectors. look at the voltage difference on the two. the blue channel you can see all the hash and it spikes to 8 v and then looks like its trying to go down. it almost looks as if…

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Albin Diagnostician
Washington
Albin Default
 

That Looks like things go south at the end of screen 16 and stay that way as long as the engine is running fast. If you slow your capture rate down to 2 MS per division, your scope won't miss so much data. Since the signal is stable at idle, and only goes bad at high speed, I would suspect the sensor is not reading properly. All the noise in the signal is either caused by a poor connection at…

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James Technician
California
James Default
 

It looks like the signal wire is touching ground somewhere. Look for bare wires.

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JB Owner/Technician
Minnesota
JB Default
 

Plus 1 for an overlay harness. You could also backprobe a ground at the suspect sensor connector to see if that helps. Always a quick and easy test.

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Caleb Diagnostician
Indiana
Caleb Default
   

Is that a coil leaking secondary into the circuit? Looks like it happens after car is running? Put a trigger and see if the problem lines up with a coil firing event. Just an idea.

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Ray Diagnostician
Ontario
Ray Default
 

The bad cmp pulses don't line up with the ignition spikes.

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Caleb Diagnostician
Indiana
Caleb Default
 

You are correct. Thanks Ray.

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Phillip Diagnostician
Alaska
Phillip Default
 

I don't think I under stand could you explain?

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Ray Diagnostician
Ontario
Ray Default
 

This capture is from a 2011 Ford Edge 3.5L and you can see some of the the ignition spikes in the cmp sensors.

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Phillip Diagnostician
Alaska
Phillip Default
 

Ohh okay I see what you are referring too.

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Phillip Diagnostician
Alaska
Phillip Resolution
 

So I have been able to conclude this vehicle and make a happy client. So after reading your responses and taking your suggestions, I want back to some basics along with just some system analysis that I over looked, cause well I probably got arrogant. So I looked for things the B1/S1 CMP had in common and found B2/S1 CMP shared one of the wires, as a member had pointed out. So I watched both of…

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Ray Diagnostician
Ontario
Ray Default
 

Good work and thanks for posting the fix!

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James Technician
California
James Default
 

I am glad you found it. Bare wires are tough to find sometimes. I knew it was grounding out by the looks of the signal.

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