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Car: 2002, 9-3 SE, 2.0T, B205R with 88,400 miles.
My wife would like to sell my car due to the high cost of repairs. Since I love this car and want to minimize the costs, I have become a DIY mechanic and would greatly appreciate any advice.
The problem is only present on warm/hot mornings (from spring to fall in Nashville, TN) and only for engine starts following 8-10 hours of down time. Basically, the problem occurs the first start each morning and immediately after work. After the initial problem start, the engine can be stopped for hours and restarted without any stalling, for example if I need to run errands. This problem has been present for about 12 months and was completely absent during our winter. The car is housed overnight in a garage without climate control.
During a problem start, the car will crank and catch immediately. Approximately 2 seconds after starting and idling normally, the engine attempts to stall for approximately 3 seconds. Then the engine returns to normal idling and does not exhibit any other symptoms. The check engine light is not illuminated and there are no fault codes stored in the computer.
Replacing the NTC coolant temperature sensor and the fuel rail fuel pressure regulator did not affect the symptoms. I also replaced the spark plugs at 88,300 miles with NKG spark plugs, the direct ignition cassette (DIC) at 84,300 miles, fuel filter at 82,700 miles and the crankshaft position sensor (CPS) at 84,300 miles. Changing the CPS was to address the unrelated issue of failure to start after the engine was at operating temperature.
This weekend, I purchased a fuel pressure gauge to check fuel pump output. I stalled the car by pulling the fuel pump fuse during idling. Then, replaced the fuse and attached the fuel pressure gauge. Read ~10 psi. I had my wife turn the key to on. While the pump ran for ~2 seconds the rail pressure was 43psi (correct as reported in WIS). After the fuel pump shut off but prior to turning the key to start, the pressure immediately dropped to 37psi. During a problem start as described above, the fuel pressure surged above 43psi as the engine tried to stall. I had expected the stalling to parallel a drop in pressure.
WIS also reports the residual rail pressure should be 33psi after 20 mins and my rail pressure was in fact 33 psi after 20 mins. However, I left the fuel pressure gauge attached and the rail pressure dropped to 25psi after 3 hours and to 10psi after 14 hours. With the engine idling at operating temperature, the fuel rail pressure was approximately 35psi and jumped to 43psi if I removed the vacuum line from the intake manifold. I think the fuel pressure behavior with the engine running is correct and the problem is not with the fuel pump.
Right now, I think the problem may lie with a faulty fuel pump check valve in the feed line. But, I would like a second opinion before dropping the fuel tank to investigate. Also, should the rail pressure immediately drop from 43psi after the pump stops but prior to engine start? And should the pressure continue to drop overnight?
posted by 129.59....
, Tue, 21 Jul 2009 09:07:46, Wed, 22 Jul 2009 11:17:12, Mon, 20 Jul 2009 10:05:25, Mon, 20 Jul 2009 13:44:14
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