Low Injection Control Pressure (ICP) Making life interesting
Posted to HD/Fleet Forum on 4/26/2014
10 Replies
I just wanted to share this on iATN as I feel that I have
not contributed much lately. The above truck was brought to
us from another shop that found a low ICP concern. The truck
shut down on the customer and would not restart until it
cooled off. After that it would only run for several minutes
before stalling again. A pretty straight forward issue on a
6.0L.
First, I scanned the PCM and found a low ICP while cranking
code. The oil level was good but the oil was dirty. So, I
flashed up the truck and watched the data stream. Right away
the IPR duty cycle is a little high at 30% but the engine
was cold. Within 2 minutes it started to climb to 85% and
was unable to match the desired ICP value. Shortly there
after, it stalled.
With the ICP sensor in the HP pump cover on a 2003 engine, I
removed the left valve cover and performed the air pressure
test. Right away I could hear a leak internal to the engine
with the IPR closed. The air leak could be heard loudest
from the oil filter stand pipe. From my experience this
indicates a damaged piston-block in the swashplate pump such
as this.
[2003 Ford F-350 Super Duty Lariat, Engine/Propulsion
Photo]
The IPR had some small metal debris in the screen and the
ICP sensor was leaking though the sensor bias was still
good. So, I quoted the job with HP pump, ICP, ICP pigtail,
IPR, oil change and all needed gaskets. Also, I would change
the reservoir screen under the oil cooler. The quote was
approved and the work began.
With the truck back together is started right up. I idled it
for a while and watched the IPR duty cycle. It was still a
little high but the system did have air in it.
Unfortunately, this was not the case. The IPR duty cycle
started to climb once again. This time though it did not
stall but ran at 85% all the way up to operating
temperature.
Great, off comes the left valve cover again and more air
pressure testing but no leaks were found. I rechecked the
IPR screen and tested the electrical circuit to the IPR, all
were good. An interesting note is that the IPR % shown in
the IDS data logger is not actual duty cycle. At 95%
commanded, I saw 64% on the signal, much like a 7.3L. Next,
I blocked of the left rail and cranked. Okay here is the
interesting part, pressure went up to 1100 psi when 2300 psi
was commanded but on the next crank I could only get 360
psi. After sitting for a while the same thing would occur,
enough pressure to start and then 360 psi on the second
crank.
At this point I started second guessing myself. I know the
original pump was bad and under closer examination I found
the drive shaft seal had blown out of it. I used a Bosch
Rexroth pump which is the OE unit. Did I miss something on
installation or did I get a bad pump? Base engine oil
pressure was good so it wasn't a supply issue as pressure is
measured virtually in the reservoir. My next move was to
test the flow of the HP pump. I measured 240mL/10sec of
cranking, which is a very good reading from my experience.
Generally, 160mL area will barely run the engine.
Knowing that I was only pressurizing the system to 150 psi
and my issue was at 360 psi or 1100 psi, I removed the right
valve cover to block off that bank. With just that bank
blocked off pressure spiked to 3600 psi and settled down at
the desired 2300 psi. Was it an injector leaking, the STC
fitting or the rail itself? Well it was a mess. The oil rail
was loose. There were stripped bolt holes and broken bolts.
The last mechanic under here had created quite a mess over
torquing the hold down bolts and tried using longer ones (of
a lower grade) to patch it together.
With this repaired the system has no problems building
pressure. Now I know using nitrogen at a higher pressure
would have found this problem but I just wanted to share in
my fun for the week.
Ryan from British Columbia
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