2006 International 4300 rough idle/surge issues

Good evening everyone,

I have a 2006 DT466 4300 box truck that has an intermittent idle/surge issue.
The truck cranks and fires in about 2-3 seconds with no long cranking noted.
Today I let it warm up and it was purring like a kitten. We drove about 3-4 miles back to the parking yard and I let it idle for a little while to cool down before turning off the ignition.
This evening I did my pre-trip and didn't notice anything loose or unusual. I started it up and the truck idled fine until I turned on the AC. After the AC was switched on, it ran rough and surged like it was trying to catch up. It surged when I put it in drive but when I put it in neutral, the idle almost smoothed out for the most part. Idle is around 700 RPM and makes good power through the gears with no noticeable power surge or loss.
I have replaced the IPR as the top two O-rings were damaged and the screen was missing. After replacement, the truck ran really well until today. After I got back and let it idle for a few minutes to cool down, I switched the truck off. About 5 minutes later, I restarted the truck and there was no hesitation/rough idle or surge. I turned on the AC, no idle change. I put the truck in gear and no surging or idle roughness noted.
The truck has had a full PM in the last 1 month (full lube and all filters changed) and we drove it back from California without any issues. Really would like some input @Inderjit @Heavyd. I have video of it running rough if this would help. There are NO fault codes or check engine lights on the dash. We had this issue before I had changed out the IPR where it would actually stall out. It would crank right back up but would idle really rough and had no power.

 

I'll try this as well. Can you give me a location for these sensors please
?

 

Thanks for the quick reply, I had my answer all typed out and the internet went down. Anyway, The IPR screen was metal and most of it was missing.
It looked like it was punched out because it had straight edges in the shape of a hexagon.
I'll check all the connections and check for rubbing. You are correct, the ICP sensor is under the
valve cover. I'll check everything out like you've suggested and let you know what I find.

 

Inderjit, ]I would start by inspecting the connectors on the clean power harness
and check the harness for wear and corrosion as well as the fuses in
the battery box. I have seen the power wires rub through and green
corrosion on the wire bad enough that the wire would crumble when
touched but it still ran at that point. The connectors can loose their grip
on their mating connector over time.

I did find the 2 negative battery cables were loose and tightened them back down.
I traced everything back from the batteries and I found no loose or corroded
wires. Everything appears tight and no chaffing noted on the harnesses.

A 2006 should have three wires in the clean power harness two that
connect to the battery positive and one to the negative. One supplies
battery power to the ECM the other supplies the IDM and the ground
is shared with the IDM and ECM.

All good here

Next I would check the power and ground connections at the starter
and the stud in the block just ahead of the starter make sure they are
clean and tight. There are several power wires that come off the starter
that feed power to the cab. There is a big harness that runs near the
left side of the engine that can rub through on the intake and valve cover.
This can cause a variety of problems.

All tight and no corrosion or chaffed wires/harnesses noted

The injection pressure sensor could also be causing you issue. Do you
have access to a laptop with diagnostic software? Could you plumb a
gauge into the line from the high pressure pump to the head to verify
the sensors accuracy. On a 06 I believe the sensor is under the valve
cover.

Servicemaxx J1708 the Navistar software for the pre 2007 engines is
a free download from their website.

If the IPR screen was missing it probably went through the pump. Was
it plastic or metal? If metal it may have damaged the pump. The high
pressure pump is fed unfiltered oil. Over time the small bits of metal
that come off the valve rotators and rocker arms and other places can
damage the high pressure pump. I have never seen the inside of a high
pressure pump. I believe they are a piston pump. If a valve in the pump
fails the pump might have a pulsation in the supply that could effect the
idle and power.

On a side note, I was unable to reproduce the issue today. I started the truck
normally with the AC off and when switched on, no engine surging. This is
frustrating to say the least. @Inderjit what is the part number for those cables
for the servicemaxx computer software. I have the program, just not the cables
for my computer.


@Heavyd
I unhooked the EGR valve and there was no difference in the performance.
It did throw a yellow engine light which went away after being reconnected and the ignition turn off and on
I did this when the engine was cool and at temperature. No difference noted
when it was unhooked. Did not check the exhaust back pressure yet.