7.3L OBS Ford

[AKnate]

Trying to figure a power issue.

Had sort of rough idle, but otherwise ran ok. Would fume the yard out if left running though.

Put rebuilt 160cc injectors. Ones before were a mixmatch and I had 2 stick open.
Figured the idle shake was from that but still doing it. No smoke, idles about as clean as any of my other diesels.

Idle shake gets bad enough it shakes the mirrors and is tough doing paperwork... writing looks like I've got the booze shakes. Not always that bad though.

Also rebuilt turbo with a KC turbine and billet compressor wheel (both stock ones were chewed up from rubbing from failed thrust bearing)

Pulls great above ~1700 rpm, and ok off idle to ~1200. I can pull hills with ~5 tons in the bed in 4th at about the speed limit (and ~2k rpm) that before was ~50mph in 3rd at near redline.

But it falls on it's ass around 1200-1600 rpm. Truck shudders, and engine sounds like it's down a cylinder. That like lalalalala noise best way I can describe it.

Compression is all ~380 psi, injector balance and buzz test fine. IPR and ICP seem ok, I think.
Wide open pull it'll get to ~2700 psi and 35% duty cycle.

Pulling to a stop it'll sometimes lope 4-5 times and go down to 400-500 rpm. Actually stalled once yesterday. It's never done that before.

It's had fairly recent valve cover gaskets and pigtails. About 200hrs on the oil and about 450 on fuel fiter. It gets same fuel all my other stuff does from my bulk tank and that got a fuel station filter at the pump.

Any ideas?

 

[reptillikus]

First thing I'd try is cam sensor. If the magnet is weak I could see it having issues at lower rpm. Plus it's easy to swap to test. Inspect the pigtail for it too; there was an update to the connector, the new one has a different style of pins in it because of issues with a bad connection causing driveability problems.

I'm having a hard time with it being a high oil pressure problem since it runs better at higher rpm. Watching your ICP/IPR values when it's loping might help.

Fuel pressure? Are you tuned at all? I know you can run 150cc injectors on the stock tune but I'm not sure about 160cc. Maybe it's just struggling to get the fueling right at idle??

 

[Levigarrett76]

Agree with everything he suggested^^^^
Be nice to see ipr/icp when it lopes and tries to die. Reminds me of what watch wes work's 94 7.3 was doing that wound up being the ipr. But it was different failure point.

 

[AKnate]

First thing I'd try is cam sensor. If the magnet is weak I could see it having issues at lower rpm. Plus it's easy to swap to test. Inspect the pigtail for it too; there was an update to the connector, the new one has a different style of pins in it because of issues with a bad connection causing driveability problems.

I'm having a hard time with it being a high oil pressure problem since it runs better at higher rpm. Watching your ICP/IPR values when it's loping might help.

Fuel pressure? Are you tuned at all? I know you can run 150cc injectors on the stock tune but I'm not sure about 160cc. Maybe it's just struggling to get the fueling right at idle??

Has a 6 position tuner. It's been in the "100hp" setting since I've owned the truck.

When I first got the truck,l 6-7 years ago, it couldn't hold highway speed empty. I got it cheap from a friend because we thought it may have needed and engine.

Did fluid and filters, which helped. Hadn't been done in the probably 10 years he owned it.
Put 2 injectors which helped, and then the tuner made it drivable.

Truck had ~57k miles when i bought it, about 73k now. Something like 4500hrs though, was a BP truck in Prudhoe before my buddy bought it.
I think it was a backup truck or bought not crazy long before they updated the fleet, cause usually when they hit auction they've got like 15,000+ hours

 

[AKnate]

Thought about just having a shop sort it out, but there's none I trust.
I understand the basics on the HEUI, but hard to say if it's right/normal without have experience with other trucks.

1023 Diesel that people about suck the dudes **** was utter ****. Wanted to charge me almost $20k for a new engine back when I first got the truck. (Ended up being 2 injectors).

They told me these trucks are hard to figure out.

The bit of idle shake I can dealwith, mostly the dead power that's not right. Wasn't an issue before too, but not sure if it’s turbo?? Probably should have rebuilt turbo first then injectors instead of all at once.

 

[reptillikus]

I dunno about turbo, it's not like it's boosting at idle. Do you have a boost gauge? If so, what kind of numbers are you seeing?

I'm assuming it's the typical TS 6 position chip. Have you tested every tune to see if there's one where it runs better? What about unplugging the chip from the PCM?

Reminds me of what watch wes work's 94 7.3 was doing that wound up being the ipr. But it was different failure point.

I didn't think about the IPR, they have that junky tin nut that can come loose and cause weird problems. The pigtail for it could be suspect as well, I know I've already replaced mine. If you've never rebuilt it then it might not be a bad idea to replace the screen in it too. My IPR plug had melted and it ran weird but it was so long ago I didn't recall anymore what the symptoms were. In fact, I just discovered the whole harness on the fuel bowl on mine was all melty but since I found it doing the efuel conversion I didn't have to fix it.


I added a crossover pipe from head to head to balance the high pressure oil rails. It helps with making it run smoother but isn't a necessary mod.


Riffraff has a bunch of good tech articles on the 7.3 and the most recent one is about the cam sensor

The 7.3's Achilles Heel: The Cam Position Sensor (CPS)

The Cam Position Sensor (CPS) on all 7.3L Powerstrokes can be its Achilles heel. This sensor tells the PCM where exactly the rotating mass is in its journey. Without it, or with one that isn’t working correctly, the PCM won’t know when each piston is nearing top dead center and therefore won’t...

www.riffraffdiesel.com

 

[AKnate]

I may just put a new one of each. Cheaper than a shop even looking at the truck.

 

[Alaskan24]

I had a similar issue a long time ago with my 97 f-250 and it turned out to be voltage related. Ended up replacing the alternator due to a failed diode.

 

[AKnate]

Left me stranded.

Went to head out with a load of wood, got like 1/8 mile from home and it shut off.
Like I turned the key off.
Crank, no start

Walked to the house and got the other truck and scanner.
Tach not reading but scanner showing ~180 rpm. Code for CPS

Dunno. Internet says tach not reading = dead CPS. Went to Schucks and got a CPS ($30). Put that in while laying in the road with 50mph winds, so like -20*.. and somehow every car in town wanting to go by it seemed like

Crank, no start. No tach still.

Had to call a tow truck.

Tried to diagnose a bit in my yard, somehow the batteries went from cranking fine (I quit before it was slowing down much) to flat dead.
I just cleaned the connections a few days ago and batteries load tested fine so no idea.

I'm about fed up with this thing. All I want is to be productive and this keeps me going in reverse.

No idea if whatever it shoved up it's ass it related to the earlier issue or it's something completely different.

Why is scanner showing revs but not the tach?

 

[reptillikus]

That shouldn't be the case, the cam sensor should be feeding both. I'd have to look at the book in the morning to see the path it takes. I know my tach is off by 100rpm at 2k but I feel like it's pretty close at 100rpm.

There are junky sensors out there, I'm currently running the dark blue Motorcraft one with good luck. Make sure the connector for it is in good shape, I had one deformed pin in mine and that was enough to get it to not run right and had to replace the pigtail.

Don't even bother cranking below 10.5v - below 10v the IDM shuts off so the injectors won't fire.

Depending on the calibration, some PCMs will fire the glow plugs with every key stroke, some won't above a certain oil temp. Point being, they call for a ton of current and you can run the batteries down pretty quickly troubleshooting a no-start issue.


Which CPS code did it throw?
Quoting from that Riffraff blog here:

What diagnostic trouble codes are commonly related?

• P0340: Camshaft Position Sensor "A" Circuit Malfunction

This is the most common code. It indicates a general problem with the CPS circuit. This could be the sensor itself, the wiring, or even an issue with the PCM (though less common).

• P0341: Camshaft Position Sensor "A" Circuit Range/Performance

This code suggests that the signal from the CPS is inconsistent or outside the expected operating range. It might be intermittent or inconsistent.

• P0344: Camshaft Position Sensor "A" Circuit Intermittent

This code specifically points to an intermittent loss of signal from the CPS. This often manifests as the engine suddenly dying, then restarting after a few minutes, or experiencing random stutters while driving.

 

[AKnate]

That shouldn't be the case, the cam sensor should be feeding both. I'd have to look at the book in the morning to see the path it takes. I know my tach is off by 100rpm at 2k but I feel like it's pretty close at 100rpm.

There are junky sensors out there, I'm currently running the dark blue Motorcraft one with good luck. Make sure the connector for it is in good shape, I had one deformed pin in mine and that was enough to get it to not run right and had to replace the pigtail.

Don't even bother cranking below 10.5v - below 10v the IDM shuts off so the injectors won't fire.

Depending on the calibration, some PCMs will fire the glow plugs with every key stroke, some won't above a certain oil temp. Point being, they call for a ton of current and you can run the batteries down pretty quickly troubleshooting a no-start issue.


Which CPS code did it throw?
Quoting from that Riffraff blog here:

P0344, P0603, and P1212

Riffrapp sells a fancy pants cats meow one I thought to order, but I needed something quick expecting it'd be fixed and I could carry in with work vs dropping $200 for a tow.

Truck tach tried moving a bit here and there, but just to say moved. Definitely not reading anything near 200.
Normally it reads a couple hundred rpm.
Never paid attention if the digital one on the trans hump reads when cranking though.

Possible CPS wasn't the issue, just seemed a good chance and was cheap enough to gamble.

 

[reptillikus]

P0603 is a KAM code, if you unplugged the batteries or killed them that could be why.

P1212 means the Injection Control Pressure (ICP) sensor isn't reading as expected during engine cranking (low pressure).
Try unplugging the ICP and see if it runs. If it does replace the ICP. Motorcraft only! The aftermarket ones are junk. If there is oil in the socket or plug then it has failed for sure.
If it doesn't run then you might have an IPR problem.

 

[AKnate]

P0603 is a KAM code, if you unplugged the batteries or killed them that could be why.

P1212 means the Injection Control Pressure (ICP) sensor isn't reading as expected during engine cranking (low pressure).
Try unplugging the ICP and see if it runs. If it does replace the ICP. Motorcraft only! The aftermarket ones are junk. If there is oil in the socket or plug then it has failed for sure.
If it doesn't run then you might have an IPR problem.

Didn't touch the batteries and was cranking fine.

 

[reptillikus]

And you didn't clear any codes either? I wanna say it's 3-5 drive cycles before you won't pop a KAM code after a reset. If the code is always there even after, for example, driving it daily for a week, then you've most likely got a PCM problem. If the PCM is losing power it could lose it's memory and pop a KAM code, but it could also be a sign that the PCM itself is failing. They do BIZARRE things when the PCM fails. Been there, done that. Not fun.

 

[AKnate]

And you didn't clear any codes either? I wanna say it's 3-5 drive cycles before you won't pop a KAM code after a reset. If the code is always there even after, for example, driving it daily for a week, then you've most likely got a PCM problem. If the PCM is losing power it could lose it's memory and pop a KAM code, but it could also be a sign that the PCM itself is failing. They do BIZARRE things when the PCM fails. Been there, done that. Not issues. Think

I did a few days before trying to troubleshoot the running ussues. Probably 300 miles since m, a few being like 5-15 miles trips.

 

[Tiha]

Dead truck, No tach. I always look for the 30 amp PCM fuse first. For whatever reason ford put the fuel bowl heater and pcm power on the same fuse.

If you fuel heater went bad and popped the fuse it will never start.

Not sure you would be able to read codes with that fuse blown or not. But worth a check.

 

[AKnate]

Dead truck, No tach. I always look for the 30 amp PCM fuse first. For whatever reason ford put the fuel bowl heater and pcm power on the same fuse.

If you fuel heater went bad and popped the fuse it will never start.

Not sure you would be able to read codes with that fuse blown or not. But worth a check.

Fuses are fine. Wouldn't be able to talk to the PCM if it wasn't powering up.

 

[reptillikus]

It concerns me that you could drive it that long, and still get a P0603. Might be worth pulling PCM to inspect.

 

[Alaskan24]

Have you tried unplugging the chip to see if the truck will start. I know when installing them you have to clean the pins really well to seat them otherwise you can get a crank no start.wouldnt hurt to check for corrosion on the pins as well.

 

[AKnate]

Tried starting it since the 75+ winds are dying.
Cranked for ~4-5 secs and fired up.

 

[Provience]

Tried starting it since the 75+ winds are dying.
Cranked for ~4-5 secs and fired up.

it just hates you

 

[AKnate]

Got it fired up again to.go deliver wood. Worried about WTF is going on, but I've got **** to do too.

Started fine, a bit rough, but it's ~12* so didnt seem crazy.

Let it warm up a few mins, gave it a couple of light revs just to test things as it seemed more rattlely than normal. (Like 1200rpm)

Sounded very knocky, like an injector or two even more injector rattle knock. Maybe just cold.

But after 3rd "rev" it shut off. same as before. Crank, no start.

 

[reptillikus]

You're gonna have to test some stuff. Unplug your fuel bowl heater. Try running without ICP plugged in. Remove tuner and see what happens. Check connector/harness for IPR, and the tin nut. Check connector for cam sensor and try to get the dark blue Motorcraft one.

 

[AKnate]

You're gonna have to test some stuff. Unplug your fuel bowl heater. Try running without ICP plugged in. Remove tuner and see what happens. Check connector/harness for IPR, and the tin nut. Check connector for cam sensor and try to get the dark blue Motorcraft one.

Tried to do some testing and will barely crank now.
So went from cranked fine and ran, recranked fine. Let it sit 5-6hrs while doing other things and it's almost dead.

Nothing left on other than a phone charger was plugged. Not charging though. Barely would crank with JNC 660 even.

going to test with real tester. The am. The digital one claimed the batteries were good.
I had checked it was charging too.

 

[Tiha]

Is it hydro locking? like a stuck injector or something else causing it not to crank ?

 

[Levigarrett76]

The excess rattling says fuel/timing control issues. To me points to testing the ipr, icp and all the things in between..
Monitor the PIDs for ipr %, icp, desired icp and fuel PW. Tach Also. Log it and report to us if you can.

start at 15:00

 

[AKnate]

Is it hydro locking? like a stuck injector or something else causing it not to crank ?

No, batteries were almost dead.

 

[reptillikus]

I dunno if you still have the OEM battery cables in that thing, but that huge dual cable lug on the passenger-side battery is known for corroding internally so you wont get a good connection to the aux battery on the driver side. Worth checking, especially if youre having issues with voltage. Mine was bad and wasnt properly charging the aux battery. I replaced it a few years back along with both batteries. Back then you could still get the OEM cable from Ford, not sure if you still can or not.

 

[Gdogg]

Check fuel pressure, I took an old fuel filter cap, drilled and tapped it to 1/4npt so I could put a gauge on it.
There is a screen behind the regulator that plugs behind it.
Next is the ICP sensor, Ford calls it a “timing sensor” if there’s oil in the connector it’s junk. If it’s been replaced and the part didn’t come from the dealer it’s junk.
Next is the EBPS, make sure the tube is 100% clear, then look in the sensor and see if it’s plugged up, most times they can be cleaned and they’ll be ok.
The EBPS signal is very important for the correct fueling tables.
Last is the MAP sensor, these are rarely a problem but if they are bad it’ll cause low power.

 

[AKnate]

The excess rattling says fuel/timing control issues. To me points to testing the ipr, icp and all the things in between..
Monitor the PIDs for ipr %, icp, desired icp and fuel PW. Tach Also. Log it and report to us if you can.

start at 15:00

IPR and ICP looked fine before it started doing this. Some WOT pulls has around 2800psi and 35% ish on the IPR. My understanding is 50% is maxed out.

But haven't been able to check now aside from it was showing RPM. ~185 cranking Which I'm told is correct that the tach doesn't show much below 300-400... like just a blip.

Last night after it stalled I cranked it maybe 4-5 seconds and it was wanting to catch but the batteries gave up. Was quite windy and had storm cleanup to do so wasn't top of the list.
Had it on the charger all night.
This morning hooked it to scanner (which means ~45+ seconds key on, so glow plugs running) and it only had 3-4 secs of crank before batteries gave out.

I had tested the batteries and charging before and tested ok. Though used a new digital tester instead of my old trusty 500 amp carbon pile, so maybe the batteries are shot.

BUT once running it's making ~14 volts so would figure battery voltage wouldn't cause it to shut off. 1st time it quit, it had been running off and on all day with no sign of low batteries.
This is at least the 3rd set if batteries in ~6 years. These ones are from summer 2023 and I unhook them when it's parked while I'm at work.


I did notice the ICP has a bit of oil around it. Nothing in the connector but looks like from the crimp area. Not a bunch, just enough dirt has stuck to it in that area.

Thinking of just getting an ICP ($120), IPR ($230) and the fancy CPS ($90). They're not super cheap, but stock are nearly 30yrs and 6000hrs old (roughly 240k miles equivalent).
And by the time I can hopefully test it, then I'll need to.order and wait 1-2 weeks to arrive, which means it'll be middle of February before I could install.