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HDGENE
HDGENE, Ford Senior Master/Diesel/Trans
Category: Ford
Satisfied Customers: 5523
Experience:  25 years Auto experience, Ford ,GM, Chrysler, Asian & European
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I'm having a problem with a 7.3 powerstroke

Customer Question

I'm having a problem with a 7.3 powerstroke
Submitted: 1 year ago.
Category: Ford
Expert:  HDGENE replied 1 year ago.

Hello, what can I help you wiht?

Customer: replied 1 year ago.
I'm having a problem with a 7.3 smoking and rough idle after fire up. It will idle fine for about 30 seconds then starts to missfire. I rebuilt the engine about 8 months ago new bottom end new injectors turbo and all new sensors only thing reused was hpop and harness. I did a buzz test got a high to low on cylinder 6 took that injector out sent it to be flow tested and checked came back fine. Swapped holes with another same thing. So replaced that injector harness which was replaced during rebuild. Then noticed while valve cover was off during a buzz test all 8 injectors are buzzing on every individual cycle not just one at a time. So I swapped the idm same thing. Swapped pcm same thing. Swapped harness now can't get to start
Customer: replied 1 year ago.
I'm a certified diesel tech, and not a fool. Done over 500 head jobs in 6.0s and rebuilt numerous powerstrokes and now work for cat as a component specialist.
Expert:  HDGENE replied 1 year ago.

Ok, so the injector failed a buzz test on the same cylinder regardless of swapping injectors, new harness and still failed a buzz test.What kind of trouble codes did you get is any before replacing any parts? Base compression is good?Blue smoke,white or gray?It ran with the new pcm, you had it programmed to the vehicle?

Expert:  HDGENE replied 1 year ago.

All the injectors are enegrized during the buzz test and it spikes each one as it tests its operation so its not unusal to hear them buzz long as they are not buzzing at the same pitch at the same time.

Customer: replied 1 year ago.
Compression on all 8 cylinders is at least 405. No codes oil pressure around 550 at idle fuel pressure 63. Ipr 12% icp .84v
Customer: replied 1 year ago.
No all were at same pitch every time and voltage was just over 5v on injector plug every cycle.
Expert:  HDGENE replied 1 year ago.

Ok and what color was the smoke, fuel, oil, or water? Not unusal for a valve cover harness to fail or cause a bad connection.Youhave communication with the new pcm and no codes now>

Customer: replied 1 year ago.
Smoke was raw fuel. And yes connection with no codes
Expert:  HDGENE replied 1 year ago.

Ok so its dumping too much fuel into the number 6 cylinder regardless from what you are saying. Will it run with the old IDM?

Expert:  HDGENE replied 1 year ago.

What prompted the pcm repleacment and was it reprogrammed to the truck, new pcms come blank and need to be reflashed

Customer: replied 1 year ago.
I've swapped the injector around and the high to low for idm code still stays for cylinder 6 that's why I swapped the harness. Injector was flow tested and no issues. Heads were decked new cups seals and springs. I understand its dumping fuel somewhere but it's not bc of one individual injector. Pcm was a used with same strat code.
Expert:  HDGENE replied 1 year ago.

Ok Im just concerned right now with it not running at all first with the pcm/idm swap. Its a direct injection system so once the injector is in the cylinder it shouldnt dump fuel until it is commanded to by pcm & idm and of course high pressure oil system control. And being so its a high voltage dc system when you mention having 5 volts at the injectors? not the type of system you backprobe with a voltmeter or are you talking about checking the circuit at the idm?

Customer: replied 1 year ago.
No I checked across the board at the injector plug at the time of buzz test and all are receiving the same signal every injection cycle
Customer: replied 1 year ago.
Ohmed the wires from bulk head plug on main Harness to jump connection going to the ucvh and is fine via ford specs and test tsb.
Expert:  HDGENE replied 1 year ago.

Ok, thats just during the buzz cycle test using the scan tool. Firstthing you need to do is get it running again so I would look into putting the original PCM and IDM back in to do further testing. Run Cylinder contribution test and cancel injectors to check operation.

Customer: replied 1 year ago.
It fired right up after the idm and pcm swap. But still after a 30 second idle would fall out.
Expert:  HDGENE replied 1 year ago.

Ok, then you might be loosing IPC. You said it was over 500 when it starts, does it drop off when it wont restart? Issue with the IPR regulating oil pressure. Is the high pressure oil resouivoir full of oil

Customer: replied 1 year ago.
is full and has a new icp and ipr. Icp does not drop.
Expert:  HDGENE replied 1 year ago.

Ok is ipr readin approx 85 %

Customer: replied 1 year ago.
Was yes and 12% at idle. I swapped it from a used harness and now wont start and no connection to the pcm. so this is a separate issue than my idle/smoke. the two solenoids on the engine one is glow plug and one is for the fuel heater correct? On the forward one which I believe is the one for the fuel heater. there is a blue where that is broken off is that the hot wire to the pcm?
Expert:  HDGENE replied 1 year ago.

The forward one should be for the glow plug, they tend to melt when they fail ,the fuel heater is located under the fuel seperator bowl.this pic is the glow plug relay

Customer: replied 1 year ago.
There is no fuel bowl on this sorry should of specified. Fuel lab fuel system. Regulate return and a1000 fuel pump. The two solenoids to the left of where the fuel bowl would be one is glow plug and one I believe is for the fuel heater?
Expert:  HDGENE replied 1 year ago.

the other solenoid powers the heater yes. i dont see any blue wire comin off either relay in the schematic

Customer: replied 1 year ago.
Give me a second and I'll tell you where it runs.
Expert:  HDGENE replied 1 year ago.

Wont let me post the wiring diagram, brown and yellow go to the glow plugs brown one bank, yellow the other.Black/orange hot all times. Red wire and a purple orange wire run off to control

Customer: replied 1 year ago.
Sorry is a red and white ish yellow color didn't see someone had butt spliced a new end on it with a blue wire.
Expert:  HDGENE replied 1 year ago.

Hmm, only a solid red wire goes to either the glow plug and fuel heater relay.I listed the color of wires to the glow plug relay. The fuel heater relay are Black orange/power supply. red, and violet. the fuel relay only uses 3 wires

Expert:  HDGENE replied 1 year ago.

Purple orange on the glow plug relay is the signal wire from the pcm to ground the energized side of the relay and close the relay and send power to the glow plugs

Customer: replied 1 year ago.
Ok I figured that issue out. now I have it back to running but still the same after 30 seconds of smooth idle it falls off and starts dumping fuel. No codes. all pids are correct.
Expert:  HDGENE replied 1 year ago.

Ok good.If you run a cylnder contribution test does it show any faults besides just checking for memory codes? No codes running a KOER test?

Expert:  HDGENE replied 1 year ago.

Its odd for it to keep comingback to the number 6 cylinder if the injector is good, not setting codes. Fuel supply runs though the head and then into the cylinder through the injector and seaed by the injector cup. All you can do is check for a supply system leakdown with the engine offl\. but since it only does it when running and appears to be isolated to one cylinder, either a control or wiring issue of mechanical fault.

Customer: replied 1 year ago.
Well as of now I have no codes no pid faults swapped injector. Different harness pcm idm compression is 408 on that cylinder fuel pressure at cross over is 61 with manual gauge. I have no clue anymore
Expert:  HDGENE replied 1 year ago.

Im just surprised its not setting any codes whatsoever, no problem with ebp, baro,ipr or ipc. cam sensor/rpm issues. Passes a cylinder contribution test and key on engine running test. But it will still flag cylinder 6 on buzz test only?

Customer: replied 1 year ago.
All sensors are 8 months old from time of rebuild ford oem.
All read correctly as by my snapon scanner.
High low on 6 no matter what harness been changed. All injectors are still buzzing on every cycle high pitch.
Expert:  HDGENE replied 1 year ago.

Ok and new harness inside the valve cover so only thing that could trip same injector fault would be the wiring between the idm module and the injector.Since thats what governs how the injector fires and for how long. Try overlaying the one circuit between both with your own wiring and see if the code clears.All the major parts are flow testing correctly. Other than a cam sensor shutting the engine down and a loss of rpm signal an no restart

Customer: replied 1 year ago.
I ohmed out the harness already from idm to bulk head
Expert:  HDGENE replied 1 year ago.

I gotcha, double check it by seeing if it can carry a load by lighting a bulb and wiggling the harness. If it cant light a bulb it is a weak circuit.