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Something you can try to confirm that #5 cylinder contribution is to look at the PERDEL PIDS in FORScan. Select all 8 of them and, with a warmed up engine, idle in park or in drive and watch those PIDs in Dashboard or Table view. The log is not quite as useful for this test. The dashboard or table view averages the readings a bit and makes them easier to read.
#5 does not typically fail. #3 and #8 sometimes do. Since we are chasing a rough idle, and the injectors are rebuilt, it might be worth a look.
No compression issues - oil cap sits upsidedown on the oil fill tube with engine idling?
no compression issues. The cap would sit on the filler tube if it weren’t for the rough idle. It’ll be tomorrow evening before I can pull the perdel pods. I’ll post my findings asap.
Anything is possible of course but more often than not the engine flat won't run if there's a cps problem. The PCM's default if it sees something that doesn't jive in the CPS is to kill the motor to prevent damage. That CPS is the PCM's keystone. Without correct info of the crankshaft's position the PCM is flying blind. No idea which cylinder needs fuel when or whether the crank is even spinning at all.
...When I got out of the truck yesterday afternoon it was back to where it was before I changed the IPR. When I would stab the throttle it sorta stumbles, hesitates and then would pick up RPM’s. At one point about 20 seconds before I ended the data log, while driving, I hit the pedal and nothing happened. Held it to the floor and nothing. Then it started working again.
Yesterday you asked about the voltage being 12.71 I believe, I’m wondering if this could be an electrical issue. Or PCM issue.
Something is going on here that we have not put our finger on. These are always tough to diagnose, as they can be wiring or a component. When the pedal doesn't respond for several seconds, it can be the PCM resetting from a fault, like a power supply issue, or an intermittent wiring short. Sometimes you will see your dash light up when this happens though - CEL, WIF and sometimes other lights. A chaffing OD wire in an automatic's shift handle can cause this, but usually happens when the handle is moved.
Do you have a chip on the PCM? Wondering now about that P0603 code. It can be caused by a chip, or by removing the battery connections to do some work. Did you disconnect the batteries for any of your repairs? It can also be caused by a loose power/ground connection.
I can see your pedal trying to command fuel and getting no response. Looks like you were coasting down from about 50mph, then trying to go again. ICP, IPR, PW, MFDES all ignoring the go-pedal, but this does show your pedal assembly is working.
Does a certain level of APP override a bad IVS signal? If so, is there a duration associated with that level?
I'm not sure. Bad Idle Validation Switch is a possibility.
@Da_Coonass could you add the IVS PID and VREF to your list in FORScan? Log each time you are driving around, and if you catch a non-responsive pedal, we can check to see if the IVS released. You can remove ECT_F.
This will not affect your rough idle probably, but might help narrow down this ignored pedal problem.
Ok, grabbing at straws here but how about an intermittent load? Something in the belt drive or maybe a fan clutch. Something basically dragging on the motor and letting off so much the PCM is constantly trying to compensate.
Do you have a chip on the PCM? Wondering now about that P0603 code. It can be caused by a chip, or by removing the battery connections to do some work. Did you disconnect the batteries for any of your repairs? It can also be caused by a loose power/ground connection.
I do now. I have had a Hydra sitting in the box for a few weeks. I installed it yesterday and drove it once this morning. It was like a different truck but still rough idle. A little crisper throttle but still sluggish off of idle. Then she rips. About to go drive it again. I did disconnect the battery several times in the last few days. I cleared the codes this morning and only these came back.
I'm not sure. Bad Idle Validation Switch is a possibility.
@Da_Coonass could you add the IVS PID and VREF to your list in FORScan? Log each time you are driving around, and if you catch a non-responsive pedal, we can check to see if the IVS released. You can remove ECT_F.
This will not affect your rough idle probably, but might help narrow down this ignored pedal problem.
I will add IVS, VREF and Perdel PIDS Thank ya’ll again.
This would be alot easier if you'd just take one of our troubleshooting ideas and say it worked. We would like to get on with our lives and help others, but noooo...da_coonass has a wuf idol...
Just kidding! I'm sorry this is taking awhile - you'd think we'd have rough idle symptoms and their solutions nailed by now. There's often one missing detail that eventually comes to the surface and we all figure it out.
This would be alot easier if you'd just take one of our troubleshooting ideas and say it worked. We would like to get on with our lives and help others, but noooo...da_coonass has a wuf idol...
Just kidding! I'm sorry this is taking awhile - you'd think we'd have rough idle symptoms and their solutions nailed by now. There's often one missing detail that eventually comes to the surface and we all figure it out.
hey don’t forget poor fuel mileage I really do appreciate all the effort and input. I have lurked in the shadows of this forum since 2017 and have asked a question here and there but knew one day I’d have to tap the brain trust here and knew the brain trust would help me like I’ve seen you all do for many a other 7.3 owner that’s in over his head. My truck runs and drives but it has always, or for as long as I can remember, had a rough idle, poor fuel mileage and ****ty throttle response. While it was down to replace a cracked radiator I decided to go ham and start changing and chasing. And here we are gents. Chasing. Thank you all so much.
VREF looks good at 5.04V Thanks for including both VREF PIDs so we got the right one. I don't know why FORScan includes the one that reports half the voltage (2.48V in your file).
When you view PERDELs in the Table or dashboard view, what do you see? Need a screenshot of that view. The log is showing #5 is a dead hole at times, but I don't have enough experience to confirm that its occurring enough to average as dead as it appears.
When my A/C compressor engages, the PW jumps from 2.75 to 3ms, but 3.3ms is a lot of idle load. Like udsuth78 says, from a fan clutch or something like that. Or maybe this miss is causing it.
When you view PERDELs in the Table or dashboard view, what do you see? Need a screenshot of that view. The log is showing #5 is a dead hole at times, but I don't have enough experience to confirm that its occurring enough to average as dead as it appears.
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I really do appreciate all the effort and input. I have lurked in the shadows of this forum since 2017 and have asked a question here and there but knew one day I’d have to tap the brain trust here and knew the brain trust would help me like I’ve seen you all do for many a other 7.3 owner that’s in over his head. My truck runs and drives but it has always, or for as long as I can remember, had a rough idle, poor fuel mileage and ****ty throttle response. While it was down to replace a cracked radiator I decided to go ham and start changing and chasing. And here we are gents. Chasing. Thank you all so much.