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10-11-2010 08:12 PM #1
Car suddenly not starting - Trying everything
1996 328i 160,000 miles
Rebuilt the top end a year ago
Car has been running great for the last 10 months. Started having rough idle suddenly and now a week later, car will not start.
The starter is cranking strong. I can hear the fuel pump pressurize for about 3 seconds before I try to start and I have gas coming out at the fuel rail. I checked all the fuses and swapped relays where I could. The plugs, injectors, pre-cat o2 sensors, fuel filter, battery, crank and cam sensor are all 10 months old. Also cleaned the MAF.
I am getting P0173 and P0170 codes. Looking through archives, seems that is usually MAF, o2 sensor, or vacuum leak. I have been inspecting the entire intake area, and not much luck. Still wondering if fuel pump could be the issue or maybe Crank Position Sensor went bad.
Seems I am getting fuel, I think, but something is keeping computer from telling it to fire.
Any suggestions, thought, or just sympathy is appreciated.
10-12-2010 12:23 AM #2
My '95 325 will run with bad O2 and no MAF.
When the O2 sensor goes bad the engine starts and runs normally. I believe the computer ignores the sensor and runs on default values. In any case, the O2 sensor doesn't work when starting an engine anyway. So I don't see how a bad O2 sensor could cause a no start condition.
Disconnecting the MAF gives a fault code and check engine light, but the engine will still start and idle with no problems. Again, a bad MAF shouldn't cause a no start condition.
BUT: My car is OBD1, and your car is OBD2, so I don't know if this is useful info for your car. Also, I am a rank amateur. This advise may only be worth what you paid for it.
Did you try cranking with the throttle open a bit? Can you smell fuel after cranking for a while? Are the spark plugs wet? Have you checked for spark?
FWIW. If this doesn't help I can only offer my sympathy.
10-12-2010 10:57 AM #3
If the O2 sensor code is "adaptation limit reached" then you may have a leak in the system. Check the underside of the intake elbow for leaks in the accordian pleat.
Only a HUGE leak would prevent the car from starting at all, though. And it sounds like you would have noticed that. The intake hose would have to be disconnected entirely. But sometimes it can do that and appear to be connected...
Check also the cyclone separator plumbing under the intake.
The MAF code might mean you need a new MAF. They can fail suddenly (I had this happen in the X5)
But as I recall, the car still started, it just ran like crap. If you have fuel pressure, it likely isn't the fuel pump, though.
10-30-2010 04:44 PM #4
Rebuilt engine a year ago and replaced the crank position sensor. Well tested it and it was reading 2 mega ohms and not 570 ohms like it should. Replaced it and car is starting and running perfect. Surprised it failed after only 14 months. The one I bout was OEM Siemens.
Just glad it is running again
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