I’ve got a no start problem with my 97 F250 7.3. I’ve done extensive research on all the old threads, and a lot of diagnosis on the truck. I think I’m stuck. Problem started with engine missing, then it just died and wouldn’t start. I have the AutoEnginuity tool, and am getting a low ICP on cranking, as well as KOEO codes p1283, p1662 and p0381. I put 12v directly to the IPR To test it, and I get a high ICP on crank (2,400). I replaced the IPR and harness anyway, because there was an old issue with a bare wire on the connector, so I figured maybe that made the solenoid wonky with a normal signal. No help there. I replaced the batteries as well. I have a good oil level in the HPOP reservoir, and I think the HPOP is good because of the test that I did with the IPR.

I noticed today that when I unplug the ICP sensor, the KOEO codes go away, but the engine still fails to start. I’d appreciate any suggestions, as I think I may be down to the PCM...

I do have a new, cheap ICP sensor coming, just to test that (although I understand the unplug test should work...)

 

Have you checked the cps? It is the beginning of most starting problems. Without that sensor working, the rest won't be functioning properly.

Make sure you use a Ford/International part. The cheapo autobone ones don't last and I've had them be bad right out of the box.

 

Seamikeo - Thanks for your reply! Yes, back when it was running but missing, I changed the CPS with a Motorcraft one. Engine ran with the same miss with old and new CPS (and with another old one that I had as a spare). I also forgot to mention that I’ve done a couple buzz tests on the injectors and they passed with flying colors.

 

Have you used AE to see what oil pressure it thinks it is seeing, both with the ICP plugged in and unplugged?

 

The 1662 code says IDM circuit failure. Do you know anyone with an 7.3 OBS truck you could test your IDM in? If the problem follows your IDM, you have found the problem. My 96 Crew dually developed a miss. It would pass a buzz test, but indicated a problem with injector one. Swapping injectors 1 and 3, and the problem was still in cylinder 1. Turned out the IDM was bad.

 

I did measure the high pressure oil pressure with the AutoEnginuity both With and without the ICP sensor plugged in. Plugged in I get 180 psi and unplugged 2400 psi ( I think The PCM Defaults to this). It still didn’t start with the ICP unplugged though. Because the KOEO codes disappear with the ICP unplugged, I ohmed the wires from the 42 pin connector to the ICP sensor. I get full conductivity to the right pins. Oddly, On a pin to pin test, I get partial conductivity to other pins on the connector (like 6,200 ohms). I’m going to pursue that next by unwrapping the main harness and inspecting the 42 pin connector more closely. I should always get infinite ohms from one wire to a different wire, right? They all go to different sensors (and they are not the common power wires).

i haven’t looked at the IDM at all, maybe that should be my next lead. I ordered the Powertrain Control/Emissions Diagnosis Manuel and it comes in a week.

Thanks again! I really appreciate the help. Happy 4th!

 

When you saw 180psi what was the ipr duty cycle %?? If it's high then you might have injector orings failed. You prob already know it takes 500psi to fire the injectors.

 

IPR duty cycle was high, at 55%. I was able to generate 2400psi high pressure oil with 12v directly to the IPR, so I’m thinking there’s Nothing wrong with the high pressure system itself, right?

Ive checked all the sensor circuits back to the 42 pin connector and they’re ok. I think I’ll re-run that 12v test on the new IPR and make sure I actually saw that 2400psi (it gives the same reading with the ICP unplugged, so maybe I screwed up that test). I’d love it to be an o ring!

Thanks for your help! I really appreciate it as I’m not figuring this out on my own.

 

in the arena with the IDM, it may be worth your time to perform this test:


https://www.ford-trucks.com/forums/a...6&d=1564842340

it will help to make sure you don’t have a wiring issue with the injectors or a possible dead short

 

Thanks! I’ll give it a try tomorrow.

 

I re-ran the 12v test on the IDM, and only got 180 psi this time! I must have had the ICP unplugged last time! In response to your posts to look at the injection system, I pulled the passenger side valve cover and saw this:

Burned up connector on UVCH

I’m sure this is causing my KOEO codes, but probably not the low HP oil pressure. I pulled the injectors and the o rings look pretty worn out. Also I think the oil is getting diesel in it. I’m going to replace bothUVCHs, and all the injector o rings, then I’ll report back. I really appreciate the responses that I’ve gotten. If not for you guys, I’d still be stuck in some rabbit hole chasing down unrelated wiring!

 

So I replaced the UVCH harness and put new o rings on the injectors. I also did the IDM test and verified that the injectors homed out ok and the wiring was good. I still got the no start condition and the same codes, so I replaced the IDM. Now it starts fine. The HP oil pressure is good, at around 600 at idle. However, it “misses” really bad, with the HP Oil pressure dropping below 500 and the rpm’s dying immediately, then it recovers. I disconnected the injectors one by one, and all of them are contributing. I get the same erratic missing with and without the ICP plugged in.

Does anyone know if one sticking injector will cause the entire engine to drop in rpm and HP oil pressure that quickly? Or, can a melted UVCH splash noth an IDM AND a PCM? I’ll try to post a video of Autoenginuity readings.

 

Trying to post the Autoenginuity video. Oh, and KOEO, KOER and buzz tests pass. Oddly, it runs fine in the first part of the KOER test, no misses...