1997 5.42V Periodically stumbles & dies.

[AksoBruce]

Greetings and Salutations.

Been a minute since I posted last. Things have been running pretty good, haven't done any mods, no major repairs. Everything has been cool.

Until...

A couple weeks ago my trusty Expy, Eddie, DIED. It was like I shut off the ignition. I was able to restart immediately and get on down the road. Since then the fault has become more frequent and sometimes will not restart for a few minutes. A few times on my drives back and forth to work (10 minutes either way with traffic) she will die 2 or 3 times. Sometimes she won't die for a few days.

There is a similar thread in the 2nd gen section originally posted by GoMach from back in September of 19 titled

"2003 5.4 Periodically stumble & die. Then start and all good."​

I have read through that thread a few times and my symptoms are identical. My current inspect/repair/replace steps are also identical. Same thing, older truck. For posterity's sake, mine is a 1997 5.4 2v, Eddie Bauer Edition 4x4.

There are no stored codes. My scanner is able to read live data and can read fuel pump power. I have had it set up to watch the fuel pump power and had a co-pilot, my 15 year old Robotics nerd, watching the scanner as we drive. When the truck dies, the fuel pump power is off. Watching the scanner, when fuel pump power comes back on, the truck will start.

Reading through the other thread, it mentions a micro relay soldered into the bottom of the PDM which gets hot, breaks contact, and drops power. My PDM, though, does not have the micro relays GoMach's 2003 has. I have changed the main relay. It still dies.

These relays have power coming in from two terminals. One terminal is a low amperage to power the solenoid in the relay and the other is high amperage to supply power to the pump. One of them is dropping power, but I do not know which.

Yet, but I have a plan...

I have a remote relay connector with a short pigtail. My plan is to crimp spade connector to it and plug it into where the fuel pump relay is in the PDM and plug the relay in remotely. I will cut into the pigtail on the two different power leads and hardwire in a pair of lights and run them into the cabin so I can watch and see which side is dying. I am fairly certain it is the low amp side. I am NOT cutting into the main harness to wire in the lights. Only cutting into the pigtail of the remote relay connector.

I have attached a couple pics of the PDM for reader reference.

Also, in the pic showing the top of the PDM you will notice an arrow on the right side pointing to a secondary relay panel. Does anyone know what those relays are for? Haynes manual is useless and my buddy who works as a tech at Ford has no clue either. There is one pic showing the relays in that panel.


WIsh me luck and if anyone has a different way to go, please chime in.

Thanks for reading.

 

[AksoBruce]

Ok, update on the dying issue...It is still dying periodically but is getting more frequent and takes longer to restart. Now it has taken to dying at idle in neutral. Still no codes.

On the fuel pump issue, the two light "tool" I rigged up did exactly what it was supposed to do and told me the fuel pump is NOT losing power when the truck dies. I did manage to get a get a fuel pressure tester from a friend and tied into the pressure port on the rail. When the engine dies, the indicated pressure does not drop, so not a fuel issue.

During the time this has been going on, I have had codes pop up relating to O2 sensors, EGR, Bank 1 lean and have replaced item associated. All 4 O2 sensors have been replaced, the EGR Delta P sensor has been replaced and I have tightened up a small exhaust leak on the back 1 manifold which is a genetic fault on the 5.4 2v. I have never had an issue with the bank 2 manifold, but every so often I have to crawl in and tighten the nuts on bank 1. All the nuts and studs were replaced when I did the head swap a couple years ago, but they keep coming loose. Go figure.

Today I will change out the crank and cam position sensors in hopes to find the solution. Both the crank and cam position sensors can cause the same issue of the engine falling dead for no apparent reason, but will typically throw a code. They are relatively inexpensive and less difficult to replace than the bank 1 pre-cat O2 sensor.

One of the "strongly recommended" suggestions that was made by a REAL Ford Technician was to replace the torque converter with the explanation that if the torque converter is locked up, it will stall the engine and there will be no codes. This is true, but the vehicle runs and drives like a champ when it runs. A locked-up torque converter will cause issues when the vehicle is in gear, but not when the vehicle is in neutral. Mine is dying in neutral. SMDH.

Anyway...

Cover me...I'm going in.

 

[AksoBruce]

I think I have finally fixed it.

Thursday, 2 days ago, I did replace both cam and crank position sensors. The cam position sensor is relatively simple to change as it is on the upper end of the timing cover by the left bank cam gear. 8mm socket and a ratchet. 5 minutes. Easy.

The crank position sensor, on the other hand, was not so easy as it is behind the A/C compressor. A little over an hour for it and much cussing about Ford's bright ideas. Please keep in mind I am a die-hard Ford fan, but I would like to throttle some of their engineers sometimes.

After replacing the sensors, I drove the truck around our shop for about an hour, just driving around in circles, hard stops, slingshot starts, sitting idling in gear with my foot on the brake and had not stutters or dying. I took it out on a road test, half mile down the road, through the subdivision at the end of the road and back to the shop, around the building, back down the road, through the subdivision, back to the shop...Did that for about an hour. I even had a grumpy old Karen call the police on me because I kept driving past her house. I explained to the responding officer what I was doing, and he let me go. I took her out on the loop and took a much longer drive.

Back at the shop again, my Boss wanted to go for a ride with me to put his seal of approval on the repair. After about 10 minutes, he turned to me and said, "This truck is SMOOTH." I just nodded and smiled. He has a 2000 Toyota Tacoma 4WD that will rattle your teeth out.

The Wife and I have been running around town for two days with no problems. I took yesterday off because it was our anniversary, and we went and did everything she wanted to do. Today is typical weekend stuff. We have already been out around town and have more to do later.

The confusing part about this fix is the fact neither the cam nor crank position sensors set a code. I think the culprit was the crank position sensor because when I was doing live data scanning, there were two instances where the RPM response was questionable. One occurrence was with my scanner and the RPM response was stuck at 1300. Idling up or down did not change the response. The second occurrence was with my Bosses scanner and there was no RPM response at all. RPM's were flatlined with the engine running. These two occurrences happened very early in the diagnostic process, two weeks ago I am thinking, and never occurred again.

The old (2 1/2 year old? ) crank position sensor, being magnetic, did have a small amount of metalic mud on it from timing chain cast off. I have a magnetic oil drain plug, so I changed the oil and checked that also. It was fairly clean so I am not worried about excess wear inside the engine. I put a new sensor in and bolted everything back together.

Simple fix for a perplexing problem.

 

[whtbronco]

Really nice thread. Well done.