2003 excursion 6.0 190,000 miles

After idling for awhile, it would sometimes surge noticeably. So I replaced the ICP sensor. After replacing it, now the truck just cranks with no injector fire for the first 10-20 seconds , then it fires up. I checked the icp reading on my TORQUE app, and found why. When you turn the key on, the icp reads max pressure (around 4100 or 5v) for the first 10-20 seconds that the key is on. Then it goes to zero and it fires up. So the PCM is seeing plenty of pressure, therefore not commanding the regulator, so no start. I assume it must be a chaffed wire issue or something, I don't see how the sensor would do that consistently. I'm out of town till February 12th. When I get home I plan to replace the pigtail, as I did not do that. I may try installing the old sensor to see what happens.

Anyone have any ideas as to what could be happening? I've found two threads with similar problems, but no solution. But on those threads, they just noted that it would start after leaving the key on for 15-20 seconds first. They didn't have any icp readings, but I'm assuming they had the same thing happening, thanks for any help!!

 

The new sensor could be bad. I don't think a harness issue would be that consistent, nor would it make it read high. If anything, a bad connection or broken wire would make it read low, I would think.

 

Ok I was thinking maybe it was crossing with another power source that's only on for start up, like a glow plug circuit. But I realize that's a pretty low possibility. You're right I think the first thing I'll try is the old sensor, as it worked fine besides the occasional surge at idle. That will tell me if it's a bad sensor or wiring. Just wish it wasnt such a pain to change lol

 

Well I'm headed home tomorrow to mess with it after 19 lllloooooooonnnnnggggggggggg days at work! Any other input or ideas? Thanks