Braking booster system leak diagnostics
View Patent ↗A leak diagnostic system for a vehicle comprises a calculation module and a diagnostic enabling module. The calculation module calculates a decay rate of a brake booster vacuum. The diagnostic enabling module selectively enables the decay rate calculation based on mass airflow (MAF) into an engine and engine vacuum.
1. A leak diagnostic system for a vehicle, comprising:
a calculation module that calculates a decay rate of a brake booster vacuum; and
a diagnostic enabling module that selectively enables said decay rate calculation in response to a determination that both (i) mass airflow (MAF) into an engine is greater than a predetermined MAF and (ii) engine vacuum is less than a predetermined vacuum.
2. The leak diagnostic system of claim 1 wherein said diagnostic enabling module enables said decay rate calculation when said MAF is greater than said predetermined MAF for a predetermined period and said engine vacuum is less than said predetermined vacuum for said predetermined period.
3. The leak diagnostic system of claim 2 wherein said calculation module calculates said decay rate based on a change in said brake booster vacuum over said predetermined period.
4. The leak diagnostic system of claim 1 further comprising a fault reporting module that selectively reports a presence of a leak in a brake booster system based on said decay rate.
5. The leak diagnostic system of claim 4 further comprising a diagnostic disabling module that prevents said reporting when at least one of a brake fluid pressure is greater than a predetermined pressure and said engine vacuum is greater than said brake booster vacuum.
6. The leak diagnostic system of claim 5 wherein said diagnostic disabling module prevents said reporting when a change in said brake fluid pressure is greater than a predetermined pressure change.
7. The leak diagnostic system of claim 4 further comprising a filtering module that applies a statistical filter to said decay rate,
wherein said fault reporting module reports said leak based on an output of said statistical filter.
8. The leak diagnostic system of claim 7 wherein said statistical filter is an exponentially weighed moving average filter.
9. The leak diagnostic system of claim 7 wherein said fault reporting module reports said leak when said output is greater than a predetermined value.
10. The leak diagnostic system of claim 9 wherein said fault reporting module determines a size of said leak based on said output and reports said size of said leak.
11. The leak diagnostic system of claim 1 wherein operation of said engine is activated based on said brake booster vacuum.
12. A diagnostic method comprising:
calculating a decay rate of a brake booster vacuum using a calculation module; and
selectively enabling said calculating, using a diagnostic enabling module, in response to a determination that both (i) mass airflow (MAF) into an engine is greater than a predetermined MAF and (ii) engine vacuum is less than a predetermined vacuum.
13. The diagnostic method of claim 12 wherein said selectively enabling comprises enabling when said MAF is greater than said predetermined MAF for a predetermined period and said engine vacuum is less than said predetermined vacuum for said predetermined period.
14. The diagnostic method of claim 13 wherein said decay rate is calculated based on a change in said brake booster vacuum over said predetermined period.
15. The diagnostic method of claim 12 further comprising selectively reporting a presence of a leak in a brake booster system based on said decay rate.
16. The diagnostic method of claim 15 further comprising preventing said reporting when at least one of a brake fluid pressure is greater than a predetermined pressure and said engine vacuum is greater than said brake booster vacuum.
17. The diagnostic method of claim 16 further comprising preventing said reporting when a change in said brake fluid pressure is greater than a predetermined pressure change.
18. The diagnostic method of claim 15 further comprising:
applying a statistical filter to said decay rate; and
reporting said leak based on an output of said statistical filter.
19. The diagnostic method of claim 18 wherein said statistical filter is an exponentially weighed moving average filter.
20. The diagnostic method of claim 18 wherein said reporting comprises reporting said leak when said output is greater than a predetermined value.
21. The diagnostic method of claim 20 further comprising:
determining a size of said leak based on said output; and
reporting said size of said leak.
22. The diagnostic method of claim 12 further comprising activating operation of said engine based on said brake booster vacuum.