Just realized I posted this to my camper thread and not this forum/thread:
Began a thorough investigation yesterday which effectively ended up with open heart exploratory surgery.
I started the day with checking the harness/connectors to the IAPCV (Injection Actuation Pressure Control Valve- the thing which controls the oil pressure sent to, and used by the injectors to fire fuel into the cylinders). I actually pulled off the intercooler to manifold pipe to make this easier. After that, the task was incredibly easy. There are only about 2 feet of wiring and it appears that it comes directly from the ECU without any intermediate connectors.
There was talk of a degraded block to HEUI pump oil line. Not the case here. It was a steel pipe already and looked in good enough shape.
Rick showed up with his scope around this point, and we started with scoping the signal going to the IAPCV. The first trace we got was with the ignition on but not running. Looked like this:
It's a little tough to read on the screen, but it's showing about 9% duty cycle with a wider pulse followed by 3 or 4 narrow pulses. Over time, the signal was consistent and didn't seem to vary when poking at or jiggling the wires.
Next up we started it and kept the scope running at idle, which looked like this:
For starters, it ran like crap- indicating the problem hasn't miraculously cured itself. It never fully warmed up but after a few minutes of running it was a little bit smoother. Running at idle had it at ~13% duty cycle with the extra spikes on the scope trace. The pattern was quite consistent though, so despite our mutual lack of knowing what the trace
should look like and the fact it wasn't changing as we knocked around the wires, we were comfortable enough to say it was running correctly and moved on.
As it was already running, next order of business was to pull the valve cover. This was fairly uneventful, with consistent streams out of each injector. We did a cutout test with each injector, shutting each one down individually and observing the results. In each case, the motor roughed up when we shut one off and smoothed back out when we turned it back on.
Since it was running, one of the suggestions was to pull the plug off the IAPCV, which we did. The motor promptly died, so I guess it passed that test?
At that point we were about out of test procedures and all signs were pointing to HEUI pump. To get a thorough understanding of what may be going on with the whole system, we pulled and cut the filter to see if there were any shimmering warning signs in it. Cutting to the chase, no, there weren't. Everything looked dark and smooth and basically devoid of shiny flakes or particulates.
As we were already pretty deep into this and I really want it bulletproof on the other side of this work, we also pulled out the oil cooler to check it for flatness. There have been occurrences where the gasket in the cooler fails internally and allows dirty oil to cross into the clean side of the filter, without any external sign of a leak. It didn't appear to have an issue (gasket-wise), but putting the cooler on the bench with a straight edge, it is clearly not flat and will need some surfacing work. Will be a hassle but don't want to have to go back in there- especially if there's no external signal for an issue. This was about the end of a productive day (with many thanks to Rick) so I stepped away for the evening.
The cooler warpage (I think lens optics make it look worse than it really is, but it definitely needs some attention):
Seeing as the HEUI pump was still looking like the guilty party, I worked through the steps of its removal this morning. It wasn't too bad since all the crap was off the motor, and it's now resting on a crate with the turbo, oil cooler, and other large parts.
Next steps will be extensive- I have the IFS filter kit on order (HEUI pump to head), an oil bypass kit as well, I want to figure out if the C7 block-to-HEUI pump filter line is adaptable to the 3126, and then I have a whole bunch of crap to replace and reinstall. Good news is the turbo looks good and its bearings spin nicely.
I also pulled the compressor head while removing the HEUI pump, and that will go off for a rebuild while I am assembling other parts.
Basically, I've got a massive boat anchor in the carport at this point. I look forward to getting some parts and putting it back together.
Port:
Starboard:
) so I can swap the old one for a reman spare. I like spares. Pickup tube is clear so I guess the low pressure problem is coming from the pump itself as GD has diagnosed. Also Replacing the springs in that filter housing per the service guide GD posted.
