My 97 F250 has had a momentary engine cutout issue for a while. Monday it went to the next level.

Previously the truck would tend to cut out while going over rough roads. The behavior was very much like an ignition cycle. Power would go away, WTS light would come on. You could lift off the throttle and reapply, and the engine (still spinning due to vehicle speed) would come back to life. On rare occasions it would die during idle while parked. The frequency of this has increased in recent weeks. Monday it left me on the side of the road. During its final moments before the vehicle came to a stop the WTS light was practically flickering, as if something were rapidly cycling the ignition. After it came to a stop, the WTS light would again function as normal, however the vehicle would only crank. I got RPM indicated during cranking, taking suspicion away from the CPS. Called the flatbed and had it hauled home.

I liberated our scanner from work and got the following codes.

P0344
P0605

Next I cleared codes.

Did a Key On Engine Off self test...

P0605

Removed wiring harness from PCM, waited 1 minute, reattached.

Repeated Key On Engine Off self test

P0605.

Is it safe to say I have a failed PCM, or should I be checking out other things which may continue to generate a P0605 code?

I haven't yet been able to remove the PCM because the fender well is in the way and I can't slide it forward enough without removing some of the fender well attachment hardware. Whoever had the vehicle before me did change the exhaust over to a 3" straight pipe all the way back, complete with a post-turbo EGT sensor port. I don't know if it was ever chipped or not.

 

0605 PCED Powertrain Control Module ROM error Internal PCM failure Internal PCM failure
That can be bad news unless you have a chip.
Check all the fuses under the hood #22 & #9

P0344 CPS
RPM on the tach is not always a CPS. They are cheap to try, about $25 at the dealer. You might even get one under warranty..not sure though.

 

x2.. above. Since you experience it on rough roads I would check all battery cables including (especially) grounds. Also check the main power cable on the starter for loose or bad connections as that feeds most of the truck. Think I saw a thread a while back and had PCM relay clicking (WTS flashing) and it was loose connection on the starter.

 

I think the CPS is OK. I bought one a while ago to fix an issue which turned out to be fuse #22. Since it didn't solve the issue I swapped the original back in and carry this one as a spare.The loose / intermittent wiring connection issue is something I have been dreading chasing down, but having a starting point of grounds and the starter narrows it down enough that I'll have a go. I'll also have a look at fuse #9. I did a fuse check with ignition on and all but two fuses had voltage relative to ground. Even those which didn't I removed and checked for continuity. They were 10A rated.Will post findings when I learn more, likely tomorrow.thanks, Rory

 

Take a look at the CPS connector pins and sockets when when/if you replace it.

Also, you should check the main engine wire harness that drapes over the driver side valve cover. It's loosely wrapped with red tape. Shake the snot out of that harness while it's running. If the engine hiccps.....it may have chaffed or broken a wire in the harness, wouldn't be the first time.

 

New information...

Unfortunately I changed 2 or 3 things at once before attempting to start, for fear of dying batteries.

1. It's finally dried stopped raining for a day here, so something may have dried out.

2. I removed the fuel fliter / GPR plastic cover to better access the wiring harness Jim mentioned, and jostled it about.

3. I checked each of the four harness plugs going into the valve covers. Passenger side front (right near the oil fill cap) was saturated with oil from the inside. I blew it out and sprayed brake cleaner in to attempt to dry it.

From this point I plugged in the PCM and attempted to start - with success.

While the engine was idling I backed the truck up a few feet (its nose had been in the street).

With engine idling I jostled the wiring harness Jim mentioned again. No interruption to the engine idle.

Upon pulling forward, I got about 20 feet, then lost the engine in the same mode as before. Restart was successful.

Did a test drive in the sub, a few cutouts, always with successful restarts. Took it on the main road and did two WOT launches without incident.

So in short, I seem to be back where I was one week ago. I didn't have the code reader tonight. I'll bring it tomorrow and check for codes again.

Other observations which suggest maybe the PCM is on its way out are as follows. First I notice sometimes when coming to a stop the engine idle will dip lower than normal (<500 RPM indicated) then recover. Second, once this engine cutout thing starts acting up I notice the 2-3 upshift point and the 3-4 upshift point come sooner, such that (in the case of 3-4 at least) engine speed once in fourth gear is around 1100-1200 RPM. Typically it's 1400 RPM.

They tell me at the auto parts place that there are three possible PCMs for the 97 7.3L with ATX, and I need to get the old PCM out and read its part number. Does this sound right?

Rory

 

It's rare that our PCM's go bad. When the engine is stumbling the trans will get confused and cause a funky shift pattern. Have you checked all the engine grounds, both batteries and the ground straps? Try to get a recording scanner on it. It will record all the data as the trouble occurs, this should point you in the right direction.

The IDM's have been known let water in dues to a bad seal. It will get worse with rainy conditions until it completely fails. Remove it from the driver side fender and shake it. Listen for liquid sloshing around.

 

you said you recently had fuse 22 blow and you replaced it correct? unplug your fuel heater it can short the circuit without blowing the fuse and will kill the motor intermittantly

 

More new info - some interesting...

Re: the #22 fuse. When I had the issue in Jan, I disconnected the fuel heater element so as to prevent a repeat of that failure mode.

Finally got the PCM out. Looks like the truck was chipped, which I guess would explain the P0605 code. Plugged into the back was something by Superchips. Barcode serial number is 12001103--- (last 2 or three characters illegible).

Sticker reads:
NEW INTERSTATE CONCRETE
NAW6CARB.E2T
TDE1

THE NAW6 was stricken through with a pen and TDE1 was written in pen below it.

As for the PCM itself, these are the numbers on various locations of its barcode sticker.

NAW6
DPC-202
F6TF-12A650-AYG
*G0CS5331Q58X*
G NPF 6M181

It looks like the connections between superchips part and PCM were tight, though not clean on one side of the PCM board. Previous owner had wrapped clear shipping tape around the front and back of PCM to hold the superchips thing in place. Ironically it had either been cut once to access the chip (maybe if/when got reflahsed from NAW6 to TDE1) or the tape burned / fatigued away. The seem looks more like it was cut.

Many questions, as follows:

1. Any chance the superchips thing went south? Does superchips have a good reputation for longevity?

2. Can I just pull the superchips thing out and run, or does something have to be plugged into that open slot?

Rory

 

superchip is pretty good as far as reliability though the old gold plug in chip is only good for 40-50 hp. i'd remove it first and see how it runs, then if all is good clean the pcm connection and try again. that hole is just an access port, nothing gets plugged into it.

 

This'll be interesting to look at. I never noticed much more power than my 1995 PSD had. I did some on-road driveshaft power measurements last fall and only got just over 200 HP peak - the enginer production sticker claims 225.

If nothing has to plug into the back of the PCM, was / is there a dust cover for it? I'm surprised at the amount of shiite which got into there and is not all over PC boards. I think before I reinstall it I'll pull the cover off and treat it with some circuit board cleaner. Probably fab up something of a dust cover for it also.

Good not to know I have to plug something back in there...

Rory

 

Its very possible the chip was loose. Put the PCM back in a test then if good put the chip back in but make sure those contacts are clean and the chip is fully seated.

 

I am fixing up a front end collison 96 Ford F250 with the 7.3. I have fuel, compression, but no fire. For some reason i think the fuel shut off switch, if there is one, is tripped or there is something else wrong and the injectors are not firing. Can anyone give some insite on that.

 

Welcome to FTE!

There is no inertia switch on these trucks as they have a mechanical fuel lift pump.

Does the wait to start light come on with the key? Does the tach register any RPM when cranking? Any smoke out the tail pipe? Where was the truck hit? Sorry for the questions but they will help us narrow the problem.

 

Welcome aboard, If you will return to the forum page and then to Diesel then look to over to the right side of the 1994.5 - 1997 7.3L Power Stroke Diesel there is a link button and repost your problem with as much info as posible and you will get a bunch of help on your problem. Click on the Diesel link in this message to get back to the forum. Here is the link back the other I listed got mod.
https://www.ford-trucks.com/forums/index.php