12-14-2016 10:50 AM
You didn't say if this happened suddenly or just gradually moved to this condition. So I will just review some things that are important.
1. Be sure that all the valve lash settings (inlet, exhaust, GAV) are correct, especially the GAV. The GAV has a direct effect on the cylinder air/fuel ratio and must be correct with no tolerance.
2.The needle valves should all be in the range of about 3-5 when all the adjustments are set. Needles valves too closed can cause cylinder misfire which will cause the burn time to be long.
3.The combustion feedback sensors must be in good condition for the burn times to be accurate. Also the combustion sensor cables must be in good condition; the nominal resistance in the coaxial cable is 1 ohm.
4. The primary ignition and transformers must be in good condition. If a cylinder is misfiring because of ignition issues, the burn time may be long. The spark plug gap must be consistent at 0.011".
5. Coolant leaking into the cylinder may cause the cylinder to misfire (too much leakage, putting the flame out) or may cause the burn time to be fast (adding fuel to the cylinder, coolant is a combustible). Also the nozzle holes in the prechamber must in good condition and not eroded. This will affect combustion propagation and burn time. A bore scope inspection into the prechamber and into the cylinder can help detect a coolant leakage.
I am not sure what else to suggest. It is important to be sure that the electrical noise is within tolerance. Cat states that the maximum electrical noise(ripple) is 150 mVAC. If it is higher, check to make sure that the engine block is grounded to earth ground. Check all of the grounds in the electrical system. Electrical noise can cause all kinds of uncommon and strange happenings in the control system.
Good luck and reply back when you have other information or questions?
11-30-2016 08:42 AM
We have a g3606 that has a slow burn time on cyl 2. The burn times are set withing .1 on the other cylinders but cyl 2 will not get lower than 1.5m/s of the other cyls (approximately 5.5 m/s). The check valve, needle valve, and combustion sensor and wire have been replaced. The Pre Chamber was replaced with a refurbished one (not very thrilled about this), and the ICSM was switched with a known good unit. None of this has helped lower the burn time. The valve lash was verified and compression is 240 psig. Also, the spark plug that came out of that cyl had a brown tint to it while the other 5 had the typical ashy white color.
Exhaust temps on this cyl are inline with the other 5.
Is there something we are overlooking?
engine serial # 4zs01828