Threshold UNDERBOOST Monitoring (2014)
The pressure-based underboost diagnostic is adequate for detecting gross air system leaks; however, the emissions threshold leak to exceed the HC standard is approximately a one quarter inch NPT hole. With a leak of that magnitude, the closed loop boost pressure governor is capable of maintaining the desired boost pressure. The functional underboost monitor is not able to detect a leak of such size, so an additional boost system diagnostic is utilized since desired pressure is maintained in the system.
The closed loop boost pressure controller controls boost based predicted control targets and anticipated turbocharger position. The output value, in percentage, indicates the "control effort" required to maintain the desired boost pressure. With a boost system leak, the control effort increases. There is a temperature entry condition, torque entry conditions, a steady state requirement on manifold pressure, an exhaust temperature entry condition, an exhaust lambda entry condition, and a threshold map. If the threshold is exceeded for 4 seconds, a fault is detected. This diagnostic will also detect a turbocharger VGT mechanism stuck in the open position.
THRESHOLD UNDERBOOST MONITOR
| DTCs |
P0299 - Turbocharger/Supercharger |
| Monitor Execution |
Continuous |
| Monitor Sequence |
None |
| Sensors OK |
ECT, MAP, MAF |
| Typical Monitoring Duration |
7 sec |
THRESHOLD UNDERBOOST ENTRY CONDITIONS
| Entry Condition |
Minimum |
Maximum |
| Engine Torque |
200 Nm |
700Nm |
| Engine coolant temperature |
-7 deg C |
|
| Ambient air temperature |
-7 deg C |
|
| Barometric Pressure |
75 kPa |
110 kPa |
| MAP steady state pressure |
|
100 kPa |
| TOxiCatUs Temperature |
99 deg C |
|
| Mass Air Flow |
1300 kg/h |
| Not in Cold Start Warm-up Mode |
| Regeneration Status |
None |
TYPICAL THRESHOLD UNDERBOOST MONITOR MALFUNCTION THRESHOLDS
| If control effort percent is > threshold map for 4 seconds and Exhaust Lambda is less than 1.33, a fault is detected. |
TYPICAL THRESHOLD UNDERBOOST MONITOR (P0299) THRESHOLD MAP
| RPM/TRQ |
600 |
750 |
1000 |
1200 |
1600 |
2000 |
2250 |
2500 |
2750 |
3000 |
3250 |
3500 |
| 0 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
| 100 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
| 150 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
50 |
| 200 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
12 |
12 |
25.5 |
25.5 |
25.5 |
| 250 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
12 |
12 |
27.5 |
27.5 |
25.5 |
| 300 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
12 |
12 |
27.5 |
27.5 |
25.5 |
| 350 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
12 |
12 |
27.5 |
27.5 |
25.5 |
| 400 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
15 |
15 |
25.5 |
25.5 |
25.5 |
| 450 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
15 |
16 |
25.5 |
25.5 |
25.5 |
| 500 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
18.5 |
18.5 |
25.5 |
25.5 |
25.5 |
| 600 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
18.5 |
22.5 |
25.5 |
25.5 |
25.5 |
| 700 |
50 |
50 |
20 |
12 |
12 |
12 |
12 |
18.5 |
22.5 |
25.5 |
25.5 |
25.5 |