99 & up 7.3L Power Stroke Engine and DrivetrainDiscussion of the 99 & up 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.
truck came in with a no start issue, was running fine, died wouldn't start back???
new cps, new pcm, new hpop, truck had full force single shots and a dp tuner, removed the chip and pulled all injectors and replaced with new "reman" stock injectors, truck hasn't had the chip back on since the new pcm was installed, new ipr valve, new icp sensor, new idm, another new cps (just in case) 8 new glow plugs, has 60 psi fuel pressure key on and cranking engine, buzz tested fine, duty cycle on ipr is going from 15%-32%-23%-15%-32%-23%-15% over and over and hpop pressure at the heads with mech. gauge is spiking upwards of 1200psi then falling to around 600 then moving up and down just as the ipr % is moving, filled the hpop resevoir, and low pressure oil pump is making 50psi so resevoir is staying full, what am I missing here???????? this thing is driving me crazy, also worth mentioning that both valve cover gaskets are new, no burnt plugs on the harness????? any ideas??? thanks! Dusty
no smoke at all, and no oil whatsoever from the spill ports on injectors, it's like I'm getting oil to the injectors but for whatever reason the solenoids aren't opening, yet the solenoids sounded fine and got nothing negative on the buzz test, I'll check your link thanks!
update, bought another new cps just in case, still no fire, oil pressure on mech gauge to head is now reading between 500 and 700psi cranking, and seems to take a couple seconds to come up as you crank, hooked two battery chargers up verified on the scan tool my voltage wasn't too low while cranking, swapped relays and checked fuses again, tried cranking with shifter in N thinking it could be a safety of some sort on the shifter column as suggested to me? tried another IDM with yet another good buzz test, somebody help please!! this thing is driving me crazy!!!!! lol what would cause me to have no oil from the injectors? could I have a bad PCM? I felt like that the pcm had to be communicating with the IDM etc to be able to buzz it and take data streams while cranking am I correct in assuming that?? as well as assuming I have no problems with the UVC harness or else it should show up in the buzz test as well? I'm gna have to burn this thing if I can't find something soon!!!! lol thanks!
Can you read ICP directly from the PCM instead of your mechanical gauge? Could be that the ICP sensor is biased and preventing the PCM from firing the injectors. Try pulling the ICP sensor wiring connector loose and try starting it that way. You'll get a check engine light, but that's because the sensor is disconnected. The PCM will use default values to control the IPR.
Your IPR duty cycle going up and down while cranking is strange, unless you have a leak that only happens when pressure goes up, then reseals itself. Stranger things have happened.
unplugging ICP doesn't change anything and I am reading duty cycles etc on a snap on scanner, and I was told the duty cycle looked ok, that it was ramping up pressure and then when it pcm was satisfied it had enuff hpop pressure to fire it was going back down?????
fuel pressure was checked at the back of the filter housing, I'm thinking that the fuel making it to the injectors isn't the problem, but making it through them like you said is, due to the fact that I have no oil being exhausted from the injectors, which (I think??) is telling me the solenoids aren't working on the injectors at all, but why???? with 8 new (reman) injectors it seem highly unlikely that its the solenoids themselves, but I think I'll ohm the injector plugs just to make sure I have no voltage getting there as I suspect??? the truck has a reman PCM that was put in after the no start problem, but I'm wondering if somethings not right with it or the fuse panel? the fuse panel has a circuit board, but I don't know for sure if all the things I have seen that seem to be working or giving feedback will do so with a bad pcm/fuse panel etc. going to start checking the harness with a meter tomorrow I guess? not sure what else to look for at this point????
If you're getting a good buzz test, then that means your PCM and IDM are getting power, so it's probably not a fuse problem. And if you aren't getting any codes when you do the buzz test, that says your injector circuits are OK.
Your IPR duty cycle hunting like that doesn't seem right. It should start out at 14% with key on and that should be enough to get ICP over 500 psi while cranking. If ICP doesn't come up quickly enough, the PCM bumps up the IPR duty cycle to drive the ICP up. Typically, IPR won't drop back down until the engine starts. I don't really know why yours goes up and down, but maybe the IPR is sticking, causing overshoot, but the engine should start when the ICP gets over 500 psi, and then would probably romp a bit before settling down to a regular rpm.
When you checked the fuel pressure, which port did you use? There are 2, one pre-filter and 1 post filter, but more importantly, the latter is post check valve in the filter stem. The one that is lower and on the passenger side is the one to use.
I think I would try to verify everything at this point. When cranking, does the PCM command pulse width for the injectors? Have you performed an KOEO test? It may turn up an associated issue, or somewhere to start.
99.5 PS CC 4x4 SRW ZF-6
Triple Pillar Gauges; Fuel pres, Pyro, Boost
AE, Alldatadiy, and half a clue
- AKA "The Big White Truck"
Would a short or broken wire to cps show a code or anything on the scanner? And what do I look for on the scanner to see if the pcm is telling the injectors to fire? I saw something on the data stream that was a % and had 1 through 8 and 0.0 but the numbers never changed while cranking but I want sure what they were? I'm thinking at this point I may have gotten a bad pcm or flashed incorrect or something of that nature? ? Thanks and keep the ideas coming I sure appreciate them! !
What you're looking for is fuel injector pulse width, in milliseconds. It needs to be between 1 and 6 mS to start.
From the service manual:
A 1-6 mS fuel pulse width (FUEL PW) will be sent by the PCM to the IDM if system voltage does not go below 7 volts during cranking, engine cranking speed is above 100 rpm and injection control pressure is above 3450 kPa (500 psi). Even though a 1-6 mS fuel pulse width is shown on the NGS to be sent to the IDM, it is possible the IDM did not get the signal, due to a fault on either the CID or FDCS circuits or even the IDM. Note that low fuel pressure or no glow plugs could still be the cause of the No Start or Hard Start condition. A 0.60-ms fuel pulse width (a no fueling pulse) will be sent by the PCM when a sync pulse has not been received from the CMP sensor and if insufficient injection control pressure is present. This 0.60-ms fuel pulse width will not allow injectors to be enabled, but does keep the IDM and PCM synchronized until sufficient injection control pressure is realized.
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