- Joined
- Jul 2, 2007
- Messages
- 5,294
New PCV valve, no joy. I have noticed a trend however.
Leaving from work in the evening activates the Incline Start Assist (i.e. hill holder) while still parked before backing up. That's okay because I am in fact parked on an incline nose down tail up about 5 degrees when in my spot in the lot. ISA on the 2009 operates via the ABS/VDC module, with an inclinometer located under the shifter console telling the ISA if the car's on an incline or not. The ISA then, for 1.5 seconds or until clutch pedal is released, will hold the same brake pressure the driver had on brake pedal. After the ISA releases and I head off, the brake pedal is stiffer than usual and idle quality is reduced.
The brake booster holds vacuum when the usual tests are applied-- pedal steady under pressure when stopped, three pumps of vacuum assist available with engine off before pedal goes hard. So I'm trying to figure out the relationship between when the ISA is activated on a *cold start* why the idle quality is down and pedal stiffer than usual. It obviously means there is a vacuum issue created after the ABS module applying brake pressure. When the issue is going on, if I shut down the engine at a stoplight and pump the brake to exhaust stored vacuum, then restart, the pedal feel goes back to normal and idle quality comes back up.
Add to this mystery that the car always has DTC codes stored in history (CEL not lit) for a voltage loss to the ABS/VDC module, and for a comms loss between the ECU and the ABS/VDC module.
The check valve for the brake booster is located inside the vacuum supply hose that goes from intake manifold to the booster, so to replace it you have to buy the entire new hose for about $40.
Leaving from work in the evening activates the Incline Start Assist (i.e. hill holder) while still parked before backing up. That's okay because I am in fact parked on an incline nose down tail up about 5 degrees when in my spot in the lot. ISA on the 2009 operates via the ABS/VDC module, with an inclinometer located under the shifter console telling the ISA if the car's on an incline or not. The ISA then, for 1.5 seconds or until clutch pedal is released, will hold the same brake pressure the driver had on brake pedal. After the ISA releases and I head off, the brake pedal is stiffer than usual and idle quality is reduced.
The brake booster holds vacuum when the usual tests are applied-- pedal steady under pressure when stopped, three pumps of vacuum assist available with engine off before pedal goes hard. So I'm trying to figure out the relationship between when the ISA is activated on a *cold start* why the idle quality is down and pedal stiffer than usual. It obviously means there is a vacuum issue created after the ABS module applying brake pressure. When the issue is going on, if I shut down the engine at a stoplight and pump the brake to exhaust stored vacuum, then restart, the pedal feel goes back to normal and idle quality comes back up.
Add to this mystery that the car always has DTC codes stored in history (CEL not lit) for a voltage loss to the ABS/VDC module, and for a comms loss between the ECU and the ABS/VDC module.
The check valve for the brake booster is located inside the vacuum supply hose that goes from intake manifold to the booster, so to replace it you have to buy the entire new hose for about $40.
