Rough idle, Extremely high ICP reading at idle, IPR % stays same

1397 Views 11 Replies 3 Participants Last post by NoRalPh, 2 mo ago

JWilson72

Discussion Starter · 2 mo ago

Hey Guys!

I'm in need of some advice on a problem that I can't figure out!

2001 F350 7.3L 6 speed

Problem started about 6 months ago. Truck would run fine for a while then lose power. You could stop, cut it off and back on and usually it would run fine the rest of the day. Would do the same thing with a random rough idle. Finally one day it wouldn't start. Change out fuel pump with a new Bosch, no change. Had buddy scan truck with AE and determined IDM was bad. Changed out with a good used and it started and ran fine for a few miles until the random rough running/ rough idle came back. At idle and driving, it would randomly run like crap for 20-30 seconds then would go back to normal. Now it's idling and running rough all the time now. I changed the ICP, CPS, and IPR with new OEM. I downloaded Forscan to check, and now at a rough idle on a cold engine, ICP is reading ~24,000 KPA (3,500 psi) at idle and the IPR % stays at 4.69 whether it's at 725 RPM idle or 2,500 RPM rev. If I unplug the ICP, it runs a lot rougher with the default 5,000 KPA on the ICP and IPR is at 14% at idle and will go up if revved then. Anyone have any idea what's going on here? This truck has got me stumped now!

Any advice would be much appreciated! Thanks in advance for any tips or info!

Jordan

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JWilson72

Discussion Starter · #2 · 2 mo ago

This is the test logs from Forscan. A snapshot of the PIDs with ICP plugged in (the very high readings), and a snapshot of the PIDs with the ICP unplugged (the 5,000 KPA reading)

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NoRalPh

· #3 · 2 mo ago

So first,,, you know how simple it is to change the ForScan configuration to Imperial? Stop with that kPa stuff already!

Next, those ICP values are suspect to me. The 750psi at Idle is the default, and you're not going to see 3,500psi from it so, and I HATE to keep beating-this-Drum,,, but Where Did Your ICP Sensor Come From? (I know, they're supposed to be Genuine OEM FORD, in a blue bag, sensors but did ya buy them online???)

How many Miles on your Injectors?

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JWilson72

Discussion Starter · #4 · 2 mo ago

NoRalPh said:
So first,,, you know how simple it is to change the ForScan configuration to Imperial? Stop with that kPa stuff already!

Next, those ICP values are suspect to me. The 750psi at Idle is the default, and you're not going to see 3,500psi from it so, and I HATE to keep beating-this-Drum,,, but Where Did Your ICP Sensor Come From? (I know, they're supposed to be Genuine OEM FORD, in a blue bag, sensors but did ya buy them online???)

How many Miles on your Injectors?

Thanks for the reply! I did buy my ICP from Ebay. It was a US seller with great reviews that claimed to specialize in new OEM 7.3L and 6.0L parts since 1999. It seemed legit, but maybe not! I was thinking that would be the next thing to replace again if I dont get a definitive answer on something else to check.

As far as the injectors, the truck has 285,000 on it. I bought it in 2006 with ~120k. I've never touched the injectors so I assume they are stock with 285k on them.

Thanks again for the info!

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NoRalPh

· #5 · 2 mo ago

Yea so, unfortunately,,, the market is flooded with Chinese counterfeit sensors that look just like what you would buy at the dealership (except they sell for $30 instead of $150, and worse yet, you could pay $150 and still be sent a $30 sensor!).

I would only buy from a dealership (and there shopping online is OK) or a Real, Diesel Specific, vendor (there are several on this site, CNC Fab is active in the 7.3 forum and linked in the "Vendor Member Forum" below). I understand shopping for the best deal, I do all the time and take pride in getting a really good deal, but sometimes "too good to be true", like a ICP for under $100, is the rule.

Your Injectors are considered High Mileage and getting pretty tired. This will mean harder starts, especially Cold, and probably increasing driveability issues but, they're Expensive! Ride 'em out some until they become a bigger issue if you need...

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JWilson72

Discussion Starter · #6 · 2 mo ago

NoRalPh said:
Yea so, unfortunately,,, the market is flooded with Chinese counterfeit sensors that look just like what you would buy at the dealership (except they sell for $30 instead of $150, and worse yet, you could pay $150 and still be sent a $30 sensor!).

I would only buy from a dealership (and there shopping online is OK) or a Real, Diesel Specific, vendor (there are several on this site, CNC Fab is active in the 7.3 forum and linked in the "Vendor Member Forum" below). I understand shopping for the best deal, I do all the time and take pride in getting a really good deal, but sometimes "too good to be true", like a ICP for under $100, is the rule.

Your Injectors are considered High Mileage and getting pretty tired. This will mean harder starts, especially Cold, and probably increasing driveability issues but, they're Expensive! Ride 'em out some until they become a bigger issue if you need...

Is there any rhyme or reason as to why my truck runs even worse with the ICP unplugged though? I agree with the ICP being faulty from the crazy numbers I am getting at idle, but it puzzles me why it gets so much worse when it's taken out of the equation. Once it's uplugged, the truck cranks for 15-20 seconds before it'll start then sounds like it's only running on half the cylinders at idle (barely enough to keep it running). It smooths out a little when revved, but still goes back to a very significant miss at idle. I've always heard if the ICP is bad, it should run better with it unplugged. Any idea on that?

Thanks again for your help!

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NoRalPh

· #7 · 2 mo ago

No, you're right! That isn't what I'd expect either...

When you start, maybe compare a Cold Start with a Hot reStart for these paramaters;

In any NoStart condition we want to monitor these 4 Important parameters while Cranking on the Starter;

ICP Pressure ~ (in PSI plz, the PCM requires something over 500 before it will trigger the IDM to fire the injectors)

IPR% ~ (shows how Hard the system is having to work to make that ICP pressure)

CRANKING RPM ~ (PCM requires above 100rpm ~ 150 is typical)

CRANKING Voltage ~ (in an '02 PCM requires it not drop below 9v, in a 2000 and under not below 10v)

It's hard to read the pic in your post with the Scan Codes results, but do I see a 1211? THAT's an indication of HiPres Oil problems (most often Low ICP) but you should be Clearing Codes to remove Historical issues so to focus on Current problems.

Clear Codes, see what comes back first when you're cranking to start...

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JWilson72

Discussion Starter · #8 · 2 mo ago

NoRalPh said:
No, you're right! That isn't what I'd expect either...

When you start, maybe compare a Cold Start with a Hot reStart for these paramaters;

In any NoStart condition we want to monitor these 4 Important parameters while Cranking on the Starter;

ICP Pressure ~ (in PSI plz, the PCM requires something over 500 before it will trigger the IDM to fire the injectors)

IPR% ~ (shows how Hard the system is having to work to make that ICP pressure)

CRANKING RPM ~ (PCM requires above 100rpm ~ 150 is typical)

CRANKING Voltage ~ (in an '02 PCM requires it not drop below 9v, in a 2000 and under not below 10v)

It's hard to read the pic in your post with the Scan Codes results, but do I see a 1211? THAT's an indication of HiPres Oil problems (most often Low ICP) but you should be Clearing Codes to remove Historical issues so to focus on Current problems.

Clear Codes, see what comes back first when you're cranking to start...

Still learning this Forscan deal and I couldn't figure out how to post a good representation of the start-up numbers but on cold and warmed up start:

Voltage drops to 10.25 at lowest while cranking

IPR #'s went from 4.69 up to 64 for 3 seconds on start up then dropped back to 4.69 within 2 seconds after starting

ICP reading gradually went up to 2,000 psi during start-up then jumped to 3,000 psi when it started. Dropped to 2,500 psi after running for 10 seconds or so.

Significant miss the whole time.

Reset codes and the new codes that come up are P1282 and P1211.

Going to check with a few friends to see if they would have a spare ICP for me to try because these numbers are just nuts. Just wish I could figure out why it gets worse when unplugged with the default #'s.

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John in OkieLand

· #9 · 2 mo ago

IMO, you need to improve the battery and cable situation.
mine holds at 11.8ish while cranking, watching a Digital VM in the Power Port on the dash.

I count to 10 or 15 after the WTS light goes OFF, watching the DVM to see if the glow plugs have turned off.

hit the starter and it is running in roughly 8 to 10 seconds ( no stop watch at 50*F )

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NoRalPh

· #10 · 2 mo ago

The only reason to look at the batteries are if you can't maintain Voltage or RPM, if so Move On to something important. In Any case 10.5v will not interfere with starting or running...

I again, don't believe the ICP and the fact that the IPR% maxes-out (and that 65% is Max) means that the PCM was unhappy with ICP pressure. IPR% should Never go above @45%

Then you got a recurring 1211, you have a HiPres Oil issue as far as the PCM is concerned. With your mileage, if this is a Real issue (and not due to a bad ICP, which I really do suspect you have) then this will most likely be an Injector O-ring bleeding off too much HiPres Oil. This all assumes that we can believe that the IPR's doing its job and because there is no feedback from it, all were seeing is what the PCM is commanding it to do (and if this is another eBay sensor, who knows?)

Did you throw away your old, real, sensors?

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JWilson72

Discussion Starter · #11 · 2 mo ago

NoRalPh said:
The only reason to look at the batteries are if you can't maintain Voltage or RPM, if so Move On to something important. In Any case 10.5v will not interfere with starting or running...

I again, don't believe the ICP and the fact that the IPR% maxes-out (and that 65% is Max) means that the PCM was unhappy with ICP pressure. IPR% should Never go above @45%

Then you got a recurring 1211, you have a HiPres Oil issue as far as the PCM is concerned. With your mileage, if this is a Real issue (and not due to a bad ICP, which I really do suspect you have) then this will most likely be an Injector O-ring bleeding off too much HiPres Oil. This all assumes that we can believe that the IPR's doing its job and because there is no feedback from it, all were seeing is what the PCM is commanding it to do (and if this is another eBay sensor, who knows?)

Did you throw away your old, real, sensors?

I've still got my original IPR valve, but the ICP found the trashcan as the connector was full of oil so I didn't figure it was worth holding onto. I've got a buddy looking through his spare parts from his old pulling truck to try to find a good ICP laying around to test before buying another. Wish I would've had Forscan before I swapped the parts out so I could've got some baseline readings before throwing the "probably false OEM" 🤦🏻‍♂️ Ebay junk at it. My friend who checked it initially with AE for the no-start issue said everything looked good pressure wise at that time so I'm sure the original ICP and IPR were not maxed out while cranking as they are now.

Think my best bet at this point would be to try another ICP then go from there? Or should I try to get a mechanical gauge on the oil system to see what pressures I'm actually dealing with?

Thanks again for you advice!

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NoRalPh

· #12 · 2 mo ago

Yea, if you can get your hands on a good, real, ICP to try then that'd certainly be worth the effort!

I don't know if this still holds true (these parts forgers are pretty good at this) but we noticed at first that the knock-offs had the part# on the ICP was dot matrix printed in Ink on it and Real ones were pin-pricked on...

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