New IPR, checked several times and new pigtail.

 

Something told me you might of but I wanted to make mention so all bases covered.

 

In both threads, the advise you got was that if the pump could make the pressure it would... and it's not. Do that air test and determine if you have a leak or a bad pump. I've not heard of a bad STC fitting in the updated version but any things possible.

It's not the ICP sensor keeping it from starting. Air test it.

 

I was also told my ICP sensor was bad. So I bought 2 more to see if that piece could be fixed and eliminated from the equation. That is the reason for this thread.

You even told me if I wasn't getting .24 or so at KOEO, the sensor was bad.

I'm not blaming the lack of start on the ICP sensor, simply working 2 issues at the same time.

 

Would it be possible that your oil pressure is too weak as to cause the lower ICP V reading? Just curious since I have read both your posts and have had ICP issues causing me to do some research on this.

What I am trying to say is, does oil at the ICP stay there, meaning the sensor will read some sort of number because there is some kind of pressure? It seems that everything I have read about the ICP V reading at KOEO "should" show .18-.24 with a healthy high pressure oil system.

EDIT to add: So you "could" be getting an accurate reading with the ICP at that low of voltage because your pressure is that bad? Meaning a leak somewhere.

Anyone able to understand or am I way off?

 

Excellent question, wish I would have worded it that way!

I haven't seen anything to indicate that I'm all my reading.

 

.2 volts (around that) is simply the sensor's ZERO point for correlating to pressure.

 

Copy that!!

So bottom line is he needs to get the high pressure oil system air tested and go from there. Once that's resolved the ICP V is a moot point.

 

I did say that the ICP could be bad, gave readings of what a good one should show and then recommend unplugging it. Once we got that far, I told you that if the truck could , it would and it wasnt... but we needed to test everything to get there.

The sensor reports voltage and the PCM uses that as a reply. The throttle is opened and the PCM see's that, sends a command to say, I need this much pressure (ICP). IPR responds with a percentage of fluid. That fluid is 4000 psi from the pump, it makes constant pressure from the first crank of the key to the end, could be a little less or more, but high pressure non-the same. Fluid is sent to injectors and the response from the system (ICPV) is a reading in actual pressure.... this is what you sent. If its not enough for the demand, it sends more. All the while checking the voltage against reference voltage 5.0v for comparison. 5.0v=4000psi and as Mark posted (Bismic).

If the ICPV isn't correct, the truck will not run correctly, sounds simple. But without the right voltages, it won't start. It will run without the sensor using default values. But if the numbers are not correct, it's better to fix the issue correctly, the truck will run better with a good sensor.

You replaced the sensor and pigtail, no change... ment that it was pressure failing not the ICP itself or the connector. At that point it's an air test to find why the pumps discharge isn't making the loop... pump, STC, branch tubes, stand pipes, oil rail, injectors and back to the filter for cleaning and cooling and into the reservoir.

There is some residual pressure after the pumps shut down, no air... like holding you finger over the straw. If it all leaked back to the reservoir, you'll crank and crank and crank... finally filling the system with fluid and eventually starting the truck.

Unless there is a leak and the ICPV never sent the voltage back to say I have enough or there actually isn't enough pressure to start the truck. It reads .18-.24 with a properly functioning sensor... that's it. As pressure goes up, so does the reading until max voltage, 5.0v = 4000psi.

Yours never moved off of .07, kind of different. But in prospective looking back from the post by Bismic.

Hope this helps, all that I'm trying to do.

 

As an fyi - cheezit suggested that later model years could run an early model year ICP and get a slight power boost because the voltage/pressure relationship was such that it produced a voltage slightly lower for a given pressure than the later model year sensor (this causing the PCM to call for more pressure when accelerating).

I am running an 03-04 sensor in my 06, and have been for quite awhile. I have not experienced any performance issues (can't say for sure it helped either). Reason for posting is that the sensor calibration can be off slightly and it won't hurt.

 

Thanks for the input Randy, my last post sounded like I was upset - not the case. Internet doesn't necessarily convey correct emotion levels, I apologize if I made you feel I was upset with you.

I very much appreciate all the assistance given, without it I would be lost.

 

Now that we have the voltage hashed out, I'm back over at the North start after no hot start thread.

 

Now that we have the voltage hashed out, I'm back over at the North start after no hot start thread.

 

I also unplugged the ICP and checked it out no oil on it and still no start, would it be the ICP screen plugged?

 

This is a 5 year old thread, you might get better help of you start a new one.