I am new to Ford and new to forums, please bear with me if I miss some details.
2003 F150 SCREW 5.4 FX4 recently purchased in AZ with CEL diag from Brakemasters showed it was due to malfunction in purge valve circuit driver from pcm. I performed all standard tests and revealed the same findings, pcm driver failure. The truck had a 2-4 second extended crank day one. By the end of the first week it was 5s and every week following it would take an additional 1-2s adding up to a 15 second crank. If I left the key on 4 seconds before crank it would start right up. I drove the truck up north to colder weather and in the mornings it would crank 20 seconds and no start until the third try. 4 second stall or cycling the key three times made no difference. Once back to warmer temps a 15s crank would start it up. Fuel pressure was at spec while cranking but bled off immediately. Replaced p regulator, same outcome. Replaced pump with Delphi now pressure holds fine. Truck started first try immediately. Second try was long crank. Turned key on 4s then cranked right up but only once. Now extended crank is about 8s, Ran test light between pcm signal wire to coil, started immediately and test light lit. Turned it off and tried again, back to extended crank with no illumination at signal wire to coil. Key on engine off, pwr exist at coil pigtail. Something is cutting signal from pcm to ignite coils.
There are no codes stored with the exception of the original purge valve problem The theft light functions as it should. I purchased a good running 2002 SCREW so I have the ability to swap parts to test, Im just not sure where to begin.
Any thoughts or direction would be much appreciated!!!

 

I would start by swapping PCM and ignition switch, and of course the keys from the donor truck to see if you run into the same problems.

It could also be a grounding issue too.

 

Thank you sir, I will head outside and do that now.

 

A quick note, I had already swapped pcm with donor and held donor key against my key and had a no start condition. Will swapping out the ignition give me a different result??

Thank you for the previous reply and suggestion ManualF150!!!!

 

I may be wrong, but I think if you swap the PCM, the ignition switch has to be swapped too. I think they go together?

- Jack

 

Swapped out pcm and ignition switch have a no start condition and theft light blinking fast. Assuming pats has taken it from here. Is there a pats module I could swap out of the other truck or is this a VIN programmed pcm fault?

Thanks guys

 

Jack -- I mentioned that in my post. Yes, those 3 need to go together for the donor PCM to work.

Happy Holidays too!

 

Sweet! I just reinstalled everything but doesn't take long to unwind again. Would the pats module be considered the rap module (yellow box behind left kick panel)? If not then Im not sure where to find it.

 

So I dont seem ungrateful, thank you for the replies gentlemen and happy holidays to both of you as well.

 

IIRC it's built into the instrument cluster.

 

Fires up every time with everything swapped. Thank you kindly ManualF150!!! Clearly pcm is making the decision on its own not to fire coils for 10-20 seconds. Was hoping to avoid expense of replacement, even had registered out of town to avoid emissions.

Found a guy talked about on here, pontisteve who does pats delete on ebay. He could could get me one with my vin but I havent heard back from him in weeks. I know a pcm will have to be flashed and pats key programmed. I can live without pats!!

Thanks again

 

Thanks, wsky for letting us know that Manual's suggestion worked! It's great when things end well and, welcome to the forum! I'm glad you were able to solve your problem here.

- Jack

 

Thank you for the kinds words. Happy holidays all - stay safe.

Don't forget to pass this site on to others. We are here to help. Lots of knowledge on here and great folks that know their stuff.

 

Yes PCM, Cluster and Keys are a married set for PATS to work.

If PATS is activated, it will disable fuel.

Interesting you had multiple problems stemming from the same root cause

 

Hi Patman, I have learned that they are a married set. In fact I have been driving around with the parts truck parts sitting in place unmounted. Picked up a Cardone reman pcm from Oreillys and will take to a local guy Monday to have cloned and pats talked to.

It may seem interesting to you that I had multiple problems but to me, not so much. I picked up this truck in a pinch one night, as I needed a truck the following day and it has not served me well. The first 30 days....
both front unit bearings were shot
both front rotors severely cracked
pads worn almost to sensors
horn defective
wrong oil filter and leaking
transmission never serviced 122k fluid burnt
both axles never serviced slight whine in both (removed front to service properly)
salvage title was disclosed at purchase but after carfax, it was the second time it was salvaged and wrecked additionally another time with major damage
fuel pump check valve bad, as mentioned before
front passenger seat belt non functioning
Interior trashed so I replaced all including carpet from the King Ranch parts truck then restored the leather
starter ring gear bad spot with no engagement
dash cup holder fell out in pieces
long aluminum shavings in oil (hopefully coming from timing cover although stethoscope on pan reveals very slight knock when hot)
spark plugs original
bad pcm
Thats off the top of my head, Im sure there has been more. Approx $1500 in parts and fluids! My choices that night were trucks with 250k in my price range and I figured at 122k I couldnt go wrong. Having bought and sold all my life and as my only living these past years, this has been a great lesson for this 53 year old. A well maintained vehicle at 250k will likely serve you better than a low mile neglected one!!! I am, however determined to win this battle. I intend to remove the engine, introduce a new timing set, rod bearings and ring gear. I am certain shortly after that, although performing fine at this time, the transmission with need replaced. Once I remedy all that is sour with this truck it will be new and mine to drive for the next ten years!!!

I want to give credit to this site, as most of the work and trouble shooting I did were aided by the threads from this site. Hence the reason I decided to join my first forum or group, not sure what to call it. Nevertheless, THANK YOU to all of the knowledgeable folks on this site who have given their advise over the years. It has been MOST helpful.

Regards to all