My 2005 6.0L Excursion is at it again. I thought I had these things figured out but alas, I guess I don't.

Symptoms: Cranks really well 300-400 rpm. It kinda chugs and tries to start while cranking then when I back off the starter, it chugs a couple more times and dies.

Actions (so far):
Replaced the crank and cam sensors, replaced the wiring harness. Put a scope on the two sensors and appeared to get a good signal (I'm not completely sure what a good signal looks like, but I can see where there is a gap in the crank signal just after the cam signal and one more time between - one cam blip per two crank rotations). Since I had replaced the sensors and wires and it looked like I had a good signal, and I still wasn't getting cam/crank sync, I ordered a rebuild PCM. Nothing changed.

My obvious question: What could cause this? If it were only FICM Sync, I would have replaced the FICM, but since it can't get CMP_CKP_SYNC, doesn't that indicate that the PCM isn't properly processing the signals? Does the FICM participate in syncing the two signals or does the PCM do that? I wanted to bounce this off the community before I dropped anymore money on replacing the FICM.

Thank you for any advice. This forum is great and I have gotten a lot of great info from you all.

Snapshot while cranking:
RPM: 372
ICP Desired: 1231 psi Actual: 1231 psi
ICP Voltage: 1.56 V
Exhaust Pressure: 15.8 psi
Engine CMP_CKP sync: 0
FICM Vehicle PWR: 12 V
FICM PWR: 48.5 V
IPR DC: 37.9%

Scope of cam and crank sensors:

 

What are you using to get engine data?

Have you verified that you are getting fuel to the secondary fuel filter bowl?

I would like to see BOTH FICM sync and Cam/Crank sync values.

Post the cranking v-reference voltage

 

What codes are present? Does the rpm gauge move up when cranking? Have you ohm'ed out the cam & crank circuits?

 

This one is interesting. Especially if the rpm reported is a true/correct reading and it likely is since owner reports a sputter so it's getting sync to a point



Seems like he chasing that long crank sync issue that's commonly just a side effect of the extended crank


Fuel filters changed recently??
Does it pass a bubble test??

 

Thank you all for your help.
Bismic, I think all the values you asked for are in this graph. I am getting fuel to the second filter bowl. In fact that brings me to my second response.
BLADE35, I wasn't familiar with the bubble test so I educated myself and conducted one. Bowl fills up quickly with the key on, cranking then produces no bubbles.
87crewdually, I do get a P0335 code. I don't see the tach move until I let of the key and then it blips up while the engine turns a second while it dies. I ohmd both of the sensors from the plug (images below) and got 840 ohms and 620 ohms.

Thanks again for any and all advice,
Preston

 

Two other questions - were the new cam and crank sensors you installed Ford OEM sensors?

In your first post, you said it cranked well and you gave rpm number. In the post above you noted a glitch in the rpm reading. Is this new behavior, or was it only observed in the dash tach (and the PCM rpm value does not show any such issues)?

 

378 cranking rpm? Wow, I thought 200 was a high normal value.
Is it possible there is no compression?

 

They were not OEM sensors. The "glitch" only referred to the dash tach.

 

I hate to say it, but this is an application where OEM is highly recommended.

I have to agree w/ xcrsp440 - even w/ a 6.4L starter, I wouldn't expect to see over 250 rpm.

 

378 does seem high. It is trying to start though so I think it is getting some help from the fact that there is some fuel igniting.

 

It sounds like some fuel gets to it if it sputtering and rpm is True Reading

Can you see a FPW HIGHER then 0 consistently

X2 on compression is it even sounding During Cranking with key off

 

With that P0335 code for Crank sensor circuit A and if you have 0 pulse width I'd say you have either a junk aftermarket crank sensor and/or a short in the harness.
I can't see what pins your on but here is a diag chart to follow.

 

I guess I'm going to dig in again and replace the crank sensor. According to the diagnostic flowchart that 87crewdually posted, I should be seeing 300-400 ohms and as shown in my photo, I'm getting 620 ohms.

Grrrr, I put in what the local parts store had in stock. Wether that is the problem or not, I have learned my lesson. Peace of mind is worth a little wait.

BLADE35, I will check the FPW before I swap the sensors and make sure it stays above zero.

Thanks again for all your feedback. I will let you know what happens.

 

Any update?

 

Update: I went ahead and replaced the crank position sensor with a Motorcraft one. This is where things get a little weird. Upon mounting and plugging the sensor in, I cranked the engine and it started. Not having the fan belt on, I immediately turned the engine off. Then I proceeded to hook everything back up (a/c compressor, engine ground wire, fan belt, intake/turbo ducting, etc). Got it all put together and jumped in and turned the key and...back to square one.

Cranks but doesn't start aaarrrrrgh!!!

I walked out of my garage and bought an F-350. Ok, I have been planning on getting a 6.7L for a while, and having the Excursion ruin another vacation wasn't going to happen again this year. That's why I have been silent for a couple weeks. I haven't decided if I'm going to sell my Excursion, but either way, I need to get it going.

Is there a chance that some other sensor or short is drawing too much power from the PCM so the voltage that is going to the crank sensor is dropping enough to not register? Is there a good way to test for that?

Thanks