Ill start by saying I am an very experienced mechanic with gas engines and I am new to the 7.3 but I have a pretty good knowledge for the engine as I have been researching my issue and talking with a coworker engineeer that used to be a field service technician for navistar. I have hit a dead end for my problem I want to get some others opinions to help me through this.

Start from the begining:

I just bought the truck about 3 weeks ago and the prev owner just had a ford reman engine installed 3500 miles prior to me purchasing. The reman engine included only the long block (he reused injectors, wiring, turbo. the truck then sat for 2 years in northern florida while he deployed. after I bought it every once in a while when I am driving the ICP values on my scan gauge will spike to around 2900 or 3100 for about 2 sec and return to normal while not under a load and at about 1200 rpm when the icp values should be around 1100-1800. When this happens the the sound of the engine changes to a higher pitched and sharper, and the SES light comes on, a few times when this happedned and I came to stop right after the engine had stalled, but not every time. also when this would happen the throttle would go non-responsive for a few seconds and then would roar back to life. I then thought it was simply a TPS sensor and I replaced the pedal assembly. Which did not fix the issue. I then took it over to a friends house and hooked it up to his Snap-on Genesis to begin checking it correctly. After running the CCT and buzz test I got a code relating to the ICP out of range, as well as a P1272 cyl 2, and en EBV code (which i was expecting as the tube is broke). I unplugged the ICP and sure enough there was oil in the connector so I replaced the sensor, and I havent got around to the sorting out hte P1272 injector code yet, (from what I read need to check for atleast 2ohms across the high side and low side pins for cyl 2 and could be the inj solenoid, under valve cover harness, or loose plug on injector) After replacing the ICP nothing has changed in regards to the ICP spikes and occasional stalls afterwards, however the truck idles great and starts fine, and no smoke. I am running the inj resistance test today and if i feel extra ambitious i am going to remove the valve cover and investigate the harness and run the engine to make sure all is normal. My coworker is supposed to be digging up all his Nav field service manuals and everything he had when they launched the 7.3, which may also help, and will share on here if possible.

Any feed back as to things too look for under the VC, and or could the inj be causing this ICP spike that i am getting and causing the ICP out of range, and ICP value low code. If I dont find anyhting abnormal I am going to switch the position of two inj solenoids and see if the code follows the change. let me know if I missed something. Thanks ahead of time

 

Me thinks its time for an ipr r&r.

 

Yeah, I think IPR is suspect at this time as well, but I'm not knowledgable enough to bet the farm on it. I am willing to bet others will Atleast suggest IPR as a starting point.

 

I just printed the IPR cleaning instructions and I will over haul this after I check the resistance accross the injector, as it is pretty cold outside today and since the prev owner lifted my truck it doesnt fit in my garage. I will save the VC removal and investigations for a warmer day. Thank you for the replies.

 

Just let the air out of the tires

 

hahaha

 

I tried letting the air out lastnight, but still needed a few more inches (that's what she said) the ruck is only lifted 4" but my doors on my garage are short. I did not got anything apart yet due to having to go out to dinner for vday. How ever on the way home from work yesterday the truck acted up and I was ready with the ipr value on my scangaugeII screen and the truck acted up after leaving a light and letting off the gas, I looked down and the ipr stuck at 34 when I was coasting. I tapped the throttle a few times and it dropped back to 8. This def has to be my problem. I am going to napa after work today to buy the needed socket. To get it apart, I'm hoping its not snowing today when I'm taking this apart. Ill report back after I complete the ipr removal. I'm hoping I can get it done today, today's my anniversary so I need to get it out before she gets home from work, gives me about a 1hr window.

 

Good luck man. Sorry the tire trick didn't work lol

 

Yeah definitely sounds like an IPR problem for sure. I would watch IPR duty cycle percentage while driving and see what it does when the pressure spikes. If it's spiking high (which it sounds like it is) then that's definitely the problem.

 

I just replaced the ipr today and took it for a drive. The problem has not gone away. I'm going to take a look at the wiring and see what I find.

 

How often does this happen? Is it regular enough you can make it happen, or know how long of a trip it takes to get it to happen?

It's not uncommon for the pigtail to the IPR to get chaffed wires. If the IPR solenoid got 12v applied to it, it could account for the momentary spike in ICP. Check that wiring by the IPR first, then if you know how long it takes for the problem to show up, unplug the ICP sensor and go for a drive to see if it still does it with the sensor unplugged.

 

I can't make it happen on demand, it usually takes about 20 min of driving, when it starts acting up, it begins with me leaving a light and me giving it throttle and it acting sluggish, and all of a sudden it roars to life after a delay. Then it will continue to do this for a little while and it will stop just as random as when it started.

 

After digging through the wiring, I never found anything, but I must have inadvertently fixed it. It has not happened since Saturday..

 

Now that you have AE, start with the basics in the last link in my signature.

 

I spoke too soon it did it again this morning, this has to be a wiring issue, it was raining this morning. Did it again, the ipr stuck closed when I pulled up to a light, and didnt want to go when the light turned green and then it roared to life breaking my tires loose. Anyone have a wiring diagram for the ipr and icp circuit? Also what controls the IPR, so I can look there as well? Thanks ahead of time.