23 MPa should be enough to start. I like to see 30 MPa, but 23 should be enough to fire the injectors.
The 2 missed cam reference pulses is probably the real issue here. The ECU needs to know the cam position to determine which cylinder to fire, and if it isn't getting good cam + crank data, it won't be able to start.
I would look at the wiring to the cam & crank sensors, and make sure it is visually OK at a minimum. You can also pull the cam + crank sensors out and
gently try to wiggle the reluctor wheels with a screwdriver. Be careful not to bend the teeth even a little, as that can cause missed pulses. You are just making sure the wheels haven't come loose. But these trucks are very sensitive to power quality, so this could be a false fail due to old batteries.
I would get 2 new batteries, fully charge them, then try scanning it again while cranking. Crank for the full 15 seconds the ECU allows (hold the key at start until the ECU disables the starter). What we want to see on the scanner is:
- Actual rail pressure rise to 25+ MPa and stay there the whole time.
- With no air in the system, it should hit 25+ MPa in half a second.
- With a little air, 2-5 seconds to hit pressure isn't concerning.
- 0 missed crank pulses. Must stay at zero.
- 0 missed cam pulses. Must stay at zero.
- Main injector pulse rise to over 400 us and stay there.
- It should jump from 0 to 400+ (exact amount depends on coolant temperature) all at once. This happens when the ECU achieves cam+crank sync.
- It should happen very quickly, within 1 engine rotation, 2 at the most.
- ECU voltage >= 10 volts while cranking.
- I have had trucks start as low as 8 volts while cranking, but you really should see 10+ volts. With brand new batteries, I would expect 11-11.5 volts as read by the ECU while cranking.
If you have all those criteria met, the engine should start. Any security/anti-theft issue will allow a start, then shut the engine down after ~3 seconds of runtime. This is assuming you have good compression, etc., of course. Run the test above, and have someone watch for smoke out the tailpipe. If it meets all the criteria to start and is smoking out the exhaust, there may be a mechanical issue.
