Bad PCM?
 

I'm wondering if I have a bad PCM. My truck (01 7.3) will run fine, but then just shut off momentarily. Sometimes it will start up and run 3 seconds, sometimes 120 miles. I've changed the Cam sensor, fuel filter, swapped the idm from my other truck, all to no avail. I've read that sometimes the cam sensor signal can get lost in a defective PCM. I've checked the valve cover connections, and they are good. My only other thought is a possible intermittent cps out of the box from NAPA? Help!

Haven't heard any good words about the Parts Store's CPS. Pick one up from Ford or International. You should be good to go.

Too many reports of poor quality CPS's from parts stores, it's really about the same price from Ford or International, so it's a no brainer for me to use them.

Is there a way I can test a cps with a meter? If so, what resistance or voltage should I get?

Have you concidered cutting your loss and maybe trying another truck?

Just got this truck. It runs great, just a matter of figuring out what causes the problem. Even changing out the pcs is a few hundred dollars. Cheaper than a new truck.

:-huh

You theoretically could, I would like to use an oscilloscope personally as it will be a pulsating signal, square wave.

I think an '01 you can still see the tach move on the dash if it's working I know on '02+ you cannot though. Usually diagnostic tool that can view live data to watch RPM signal. If it is an intermittent as you say though it would be tough to catch it with a meter until it is failing.

I personally have not heard of a bad CPS taking out a PCM...basically the PCM just looses it's reference for timing of the injection event, so it shuts down to keep from missing correct firing sequence.

Thanks Big Al. Do you think I could borrow the PCM from my 02 7.3 and try it in my 01? Would I be taking a chance at ruining my PCM in my 02?

There's the advice we were looking for. A one size fits all cures-all solution to anything that ails you.

Originally Posted by Grapevine Ford Junky
"Have you considered cutting your loss and maybe trying another truck? "




http://www.fairfaxunderground.com/fo...edTheTroll.jpg

Obviously a troll. Only one post and it's something stupid.



Mowing man,
Get a cps from Ford or international. Even if it doesn't fix your problem you'll have a spare. If it does then it's a cheap quick fix.

Thanks guys. I'll grab one from Ford this morning and see what happens.

So I swapped out the Cam sensor today with a Ford one. Didn't change anything. A few notes that may or may not affect or cause the problem, but here is the info. A few weeks ago I blew a H.P. Oil line, which I replaced. While doing that, I broke a fuel fitting going into fuel bowl. I ended up replacing the fitting and the fuel lines that feed and return the fuel. Thought I did a good job of snaking them through and cleaning any crud off of them, but maybe not. The truck started and ran great for 2 days, and then this current problem. I have checked valve cover harnesses, they are good. I have tried 2 cam sensors now, it is good. I have changed fuel filter 2 times. First time there was some oily mud in the bottom of the bowl. I cleaned it, and it ran great for 100 miles, now back to the same. The bowl is spotless inside. I have also swapped the IDM from my other truck, no difference. When this truck acts up, it throws a po 344 and a po 340 code. It also runs on the odd cylinders, but not even ones. I can unplug the valve harness on that side it runs the same as plugged in. Harness has right amounts of resistance though, and the return wire is good. I'm wondering about my IPR. Also, only does it when warm. Any thoughts?:-X16:-arrgh

Have you pulled the valve covers and actually looked at the UVCH? Sounds like it could be a burnt pin making intermittent connection. Have you done the 50 cent mod yet? Also, check the connector on the driver side that is notorious for rubbing on the VC. 42 pins maybe? It's pretty easy to spot where it would rub.

PO344 = CPS circuit intermittent

PO340 = CPS circuit malfunction

Unplug to CPS check and clean the connection.