[AlaskanSalmon]

Like title says, truck is idling rough (I would call it "clunky" but not necessarily out of balance), blowing loads of smoke, and has 1% power. With WOT and two minutes I got it to 30mph. However, it is very smooth under load - it is not vibrating.

The truck: 1995 7.3l F350 with a 1996 front cover on it, 155,000 miles, 1.0AR housing w/WW2 and wastegate deleted, Adrenaline HPOP (5 mo/1000 miles ago), 160/30 FFD injectors (17 mo/6000 miles ago), CPR fuel system (19 mo/7000 miles ago), PHP hydra running economy and high idle.

The truck is parked outside my mechanic's shop. I dropped it off to have the UVCH plugs and IPR plug replaced and U-joints replaced. Ran alright to get there. When he started it up after working on it the present condition manifested.

It is cold and dark in Alaska. Here's what I found after I got off work:
-Fuel filter replaced (filthy, but no help - Fuel was clear with no oil)
-Fuel pressure is fine, even with increased load
-ICP unplug causes a very brief (< one second) change but then business as usual
-Turbo spins fine and has no play
-Truck starts up nice and fast, catches and goes in ~3 turns/sub 1 second
-On start up idle is relatively smooth for 5-10 seconds before getting really rough
-When shifting into reverse or drive rpms drop to 100-250 and the thing sounds like it wants to die. No change in idle in neutral vs park
-Revs right up to 2500 RPM in park, didn't feel rough at all (but is a fog machine)
-EGT sensor reads COLD. 200-300F UNDER LOAD at 2000RPM going down the highway. Sensor is mechanical, not a scangauge.
-Setting tuner to factory, or real factory, and unplugging made no difference in idle
-No change from unplugging EBT sensor
-Setting tuner to DD/economy actually got a little bit of power on the road, but also increased my smoke
-Warming up made no difference in how truck idles or drives

Previous issues I ignored that might be related:
-this summer I replaced the stereo receiver and put in an amp because the old one crackled above volume 10. This had a new problem of radio interference (crackle again) that increased in intensity/frequency with engine load. With a lot of weight it would kick in at maybe 1700 rpm, with none maybe 2000. Taking the tuner off didn't help. I was all ready to choke the hell out of everything when it spontaneously disappeared to never return.
-for the past year RPMs have dropped when suddenly letting off the throttle, e.g. 60mph highway throttle to none. Sometimes they would drop so low engine would die.

My thoughts:
-It doesn't appear to be fuel. Pressure is good, filter is good, pressure doesn't drop under load
-The problem seems to be across all cylinders simultaneously, otherwise why would it run so smoothly under load (albeit with no power) or at high rpm?
-Probably not the CPS? I would have swapped it but didn't bring a spare. Last replaced last summer.
-Maybe the IPR plug is the culprit? I got it off eBay. IPR is as old as the HPOP, so IPR failure seems unlikely.
-Maybe the IDM? It looks stock. I can try pulling it, thawing it, and seeing tomorrow after work. No cool friends with 7.3s to swap with to test.
-If the HPOP conked out I would be surprised - first thing after installing I ran it 360 miles, then 360 back a week later. 21.2 mpg down, 19.8 back. It's driven maybe 400 miles since.

Any ideas? I'm stumped, but I don't know that much about 7.3s. I don't really want to throw parts at it in part because it's -15 out, dark, and the shop is on the bad side of town. Do my conclusions so far seem reasonable? Any help appreciated!

 

[cjfisher]

Welcome to PSN!

"I would recommend that you first invest in FORScan (forscan.org) and a suitable adapter. I have an OBDLink EX usb adapter (should you wish to use a computer to collect data), or take a look at either a BAFX or OBDLink unit. Both BAFX/OBDLink have a bluetooth/Wifi units (there are a few folks around here that recommend them) that will would work with a smart phone (Run of the mill box store scanners and even a great number of the higher end scanners can't touch these trucks as Ford used the "heavy duty diesel" protocol for communication). Once you are setup I would capture data.. At minimum I would save RPM (really this is CPS), ICP, IPR, MAP, EOT and IVS (at least I think that is the PID for the go petal). FORScan will allow you to save the data as a .csv file which you can import into excel. The information you get from the truck will help identify what your problem really is without just "throwing parts" at the truck."

You really need to see if there are any codes stored. FORScan will also run the injector buzz test and the PCM's pass/fail cylinder contribution test (engine needs to be fully warmed up). The cylinder contribution test will generate codes related to the IDM if there are any problems there.

Cj

 

[AlaskanSalmon]

Hi CJ. I really appreciate the reply. I'm still waiting on the USB plug to show up (very excited about FORScan, hadn't seen it before), but I bummed an innova CAN scanner. No DTCs stored, and truck dies when it tries to connect while running unfortunately. So, here's what else I've figured out:

-Fuel pressure holds at 58psi (mechanical gauge on regulator) while running, but as soon as the fuel pump shuts off it drops to 0. I mean within seconds. With just pump running I hear a sound under passenger head?

-Injector pins on harness ohm out at 4.8 to 5.p at ~-10 to 0F. This seems fine to me?

-I pulled the pigtail off the IPR and got an ohm reading off the wiring running from the ECU to the IPR. This returned 750 ohms. I can't find any specs on what this should be, but I am assuming that because it is just running 12.5v signal from ECU to IPR and regulating with frequency it should be 0. Is that reasoning right?

 

[AlaskanSalmon]

Though on second thought, ohming out the IPR pigtail is giving me a reading the the entire rest of the circuit, from IPR to ECU to ECU ground through frame to battery to ECU to IPR pigtail. So that could be normal for ECU or a bad ground? But thinking about it more, if it's an electronically actuated switched the circuit should be open and I shouldn't have an ohm reading at all. I guess I don't know enough to say. Does anyone know? Or can someone with a working 7.3 take an ohm reading off the two slots of their IPR pigtail?

 

[cjfisher]

No DTCs stored, and truck dies when it tries to connect while running unfortunately. So, here's what else I've figured out:

FORScan will do this too. Especially if the engine is running rough. On my own truck I turn the key to run, then connect FORScan and then I start the truck.

Fuel pressure holds at 58psi (mechanical gauge on regulator) while running, but as soon as the fuel pump shuts off it drops to 0. I mean within seconds. With just pump running I hear a sound under passenger head?

Sounds right.. Not sure what the sound under the passenger head might be.

-Injector pins on harness ohm out at 4.8 to 5.p at ~-10 to 0F. This seems fine to me?

That is in the right ballpark. IIRC 3 to 6 Ohms is about you should see.

-I pulled the pigtail off the IPR and got an ohm reading off the wiring running from the ECU to the IPR. This returned 750 ohms. I can't find any specs on what this should be, but I am assuming that because it is just running 12.5v signal from ECU to IPR and regulating with frequency it should be 0. Is that reasoning right?

The power side of the IPR is part of the circuit that powers the PCM through the PCM relay. So you should have a bunch of connections there and with the key at run you should have 12 volts. The other side of the IPR connection goes straight to the PCM where a transistor grounds it. If you unplug the PCM connector you should have a completely open circuit. If you see resistance then you may have a wire that the insulation has rubbed through on.

Cj

 

[Patrick Feeley]

Here's the tests that get performed when there's an issue with the IPR Power Circuit (P1283). It will tell you if you have an issue with a short or open. Cheers!

 

[AlaskanSalmon]

Here's the tests that get performed when there's an issue with the IPR Power Circuit (P1283). It will tell you if you have an issue with a short or open. Cheers!

Thank you! I ran all the basic tests and the IPR seems fine (10.2), as does the IPR circuit and harness wiring. Nothing grounded out either.

Could still be a stuck IPR, and I suppose the IPR could be in spec and still failed.

I got the passenger side valve cover off last night. Everything looks fine inside. Injectors are spitting out oil when they fire, and nothing seems stuck. Just for giggles I unplugged each injector one at a time - Truck tried to die each time. Maybe the problem is in the driver side and passenger side is carrying it?

The temps have dropped to -20 so I'm not too motivated to pull the driver side valve cover off today. Guess I'll order a CPS and an IPR (plan to have the truck until I die, so spares for both can't hurt) and try them out Friday, supposed to be a balmy +1 then. Thanks for the help guys!

 

[AlaskanSalmon]

Mail service seems to be really hung up here in Alaska ATM. No OBD connector or CPS. I pulled driver valve cover. None of injectors appear to be firing worse than the rest when idling based on oil flow. Hooked up a mechanical high pressure oil gauge. Bled line to gauge and fired up truck. It took a second then started up. Didn't sound and worse with air in the line. Oil pressure spiked at start up to over 2000 then hung out at 1600 psi. This seems really high. It also seemed to wobble between 1500 and 1700. Unfortunately it was a 2000 PSI gauge as I didn't expect peak pressures at start up (they should be 500-700 at idle right?) but the needle buried on start up, so it seems to me the gauge could be damaged. But then, pressure spiked to bury it in the first place, so pressure seems way too high. What would cause this? Is HPOP output supposed to wobble? Or can injection gasses blow past a loosely seated injector (or cracked head?) to spike the HPOP oil pressure?

On top of this the fuel pressure control box (CPR fuel kit) failed today. Fuel pump would not turn on when turning over key. Truck started up with 0 fuel pressure and didn't sound any worse than last weekend. I wired up pump manually with a 12 battery charger (no spare wire on hand to wire into battery) and ran it after starting truck. Idle didn't change with pump running. Could this mean that fuel regulator is broken and restricting flow? Or pump is failed? But fuel pressure gauge reads 58 when pump runs, which means fuel supply should be fine, right? It seems wrong to me that truck idles just as poorly with zero fuel pressure as it does at 57 psi, all while oil pressure is 1600 psi. If injectors are firing correctly the motor's performance should change with change in fuel availability.

 

[AlaskanSalmon]

An update to this saga more than two months later. Been working on this as I have time - working on getting an apartment up and it turns out I have a kid on the way. Busy!

Things really pointed to the injector o-rings being bad but swapping them out produced no change to the rough running and no power - though the exhaust does smoke a lot less. It is a lot more prone to stalling out when being put in gear. The FORScan software ran in to the same problem as before when I tried to use it, but this time I could see it was specifically when it attempted to talk to the ECU that the truck dies. It did not want to connect in key-on without the engine running. I'm working on tracking down an adapter for compression testing right now, but my gut tells me it's improbable that it's a compression test issue. Whatever I find, I'll come back and share it. I've run into plenty of threads over the years where the OP never posted about what happened and don't want to be that guy.

Also, I noticed the IPR pigtail is wired backwards. The red wire runs to connector B and the red-yellow runs to A. The new pigtail was installed right before this trouble started. Theoretically the solenoid should operate the same way even wired backwards, correct?

 

[cjfisher]

Frozen Alaskan - I recommend connecting FORscan before starting the truck. I.E. get everything plugged in. Turn key to run, connect FORscan, start data logging, start truck. I'd reverse the wiring on the IPR.. Magnetic flux is directional... It still works wired backwards, but you may get a better response if wired correctly.

Cj

 

[AlaskanSalmon]

Frozen Alaskan - I recommend connecting FORscan before starting the truck. I.E. get everything plugged in. Turn key to run, connect FORscan, start data logging, start truck. I'd reverse the wiring on the IPR.. Magnetic flux is directional... It still works wired backwards, but you may get a better response if wired correctly.

Cj

Thank you Cj. You were right, connecting it KOEO worked. Thank you for pointing me at this software - it's a very cool tool. I was all set to look through the test results during my break at work (there's a lot of codes!) and post them, but the laptop crashed and wiped the data. Lesson learned, save the test logs.

I did want to ask about something strange I noticed though: the first time I ran the injector buzz test I ran it with the harnesses unplugged, just to see what would happen. As expected, there were a lot of high to low side open error codes - but only six of them. With all 8 injector circuits open I should receive 8 total high to low side open error codes, no? With the harnesses plugged in there is one incredibly loud injector, but it returns codes for three of them. Anyways, I'll run it again this weekend and see what I get.

 

[cjfisher]

It is my understanding that the IDM has a clever way to protect itself... not sure why you would be missing codes for 2 cylinders though. You could have problems in those circuits. Keep us posted.

Cj

 

[Patrick Feeley]

With the harnesses plugged in there is one incredibly loud injector, but it returns codes for three of them. Anyways, I'll run it again this weekend and see what I get.

Not sure if this is what you're hearing, but when a buzz test is run, the first noise you hear is all the injectors being buzzed at once (loud), then each individual injector will be buzzed (not as loud). Cheers!

 

[AlaskanSalmon]

Not sure if this is what you're hearing, but when a buzz test is run, the first noise you hear is all the injectors being buzzed at once (loud), then each individual injector will be buzzed (not as loud). Cheers!

Yep, figured that out when I re-ran the test today. Eight identical buzzes after the first fire. KOEO injector self test returns:
P1272: Cylinder #2 High to Low Side Fault
P1273: Cylinder #3 High to Low Side Fault
P1274: Cylinder #4 High to Low Side Fault
P1293: Injector High Side Open - Bank 1
P1294: Injector high Side Open - Bank 2

Meanwhile, the KOEO on demand returns a bad EBP circuit, expected, and:
P1283: Injector Pressure Regulator Circuit

I ran each test twice after clearing the logs/codes and got identical returns. Didn't have time today, but tomorrow after work I'll take an ohm meter to the indicated circuits and injectors and test them (again). I find it curious that 3 injectors are coming back with faults when they all sound the same during the test. My initial feeling is that injector 3, at least, is bad - I replaced the harness in December. But, I won't rule a dud harness out just yet. Will let you know what I find with the ohm meter.

Thanks guys. Happy Easter.

 

[AlaskanSalmon]

Life got in the way again. Every injector circuit ohm'd out fine. 3.1 ohms on one and 3.2 ohms on the rest. The IDM ground circuits and the injector ground shields were all open, so they're not shorted. However, when looking into the female plugs on the harness I noticed they are definitely not shiny and new in there. It looks like there may be corrosion. What's a good way to clean them out? I suspect it's not the problem, but it's worth trying before replacing something. It's either the IDM or the injectors, but I feel like the IDM is the more likely culprit as it did not pick up on the 7 and 8 injector circuits being "open" when I ran the buzz test with the harnesses unplugged. Any input before I go throw a part at it is much appreciated.

 

[AlaskanSalmon]

Well, I'm necroposting my own thread. Still at it. Tried IDM swap. No luck. Tried replacing injectors this weekend - no luck. In a desperate move I tried unplugging the MAP sensor (which I didn't know was there, the air tube has been unconnected the whole time I've owned the truck) and the power picked right up. White smoke backed off, thought the idle didn't really sound any better. But, the lost power was back! Took it around the block and found that it still smoked when the gas it put down on it and once it gets above 1800 RPM it knocks HARD, like I'm hitting the motor with a hammer hard.

The metrics when hooked up with FORSCAN and driving are perfectly normal in terms of pressures and temperatures. The truck is throwing a code for IDM failure (1298, also 1293 and 1294), but it's the replacement IDM in right now. Either it was the IDM all along and the replacement is also bad, or the IDM is fine and just throwing a code because of the higher voltage output. Can a bad IDM cause a knock? The 1293 and 1294 are baffling to me. I've been over the entire length of the harness from IDM to valve cover gaskets. I've replaced the valve cover gaskets with Alliant replacements. It all ohms out perfectly. The injectors have been replaced. Surely it shouldn't be throwing 1293 and 1294s now.

I don't think it's the IDM though. I think something's broken internally. My guess is bent rod or cracked piston? The truck is still blowing some beautiful, perfect smoke rings under load. Anyways, that's my 2 month update. Will update more eventually if I make any progress. Cheers.