Cylinder 3 Misfire, related Air Mass Meter?

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jasonharlos

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I have a '99 328i with 83,000k miles that is periodically misfiring. The check engine light comes on and I get two codes: P0303 (Cylinder 3 misfire), and P1250 (Air/Fuel Mixture, related to Air Mass Meter). It always happens on the same cylinder. Whenever the car starts to misfire, it will stop after I shut off and restart the car. I check the connector on the Air Mass Meter and it appears to be fine. Can anyone provide with some ideas on what to check? It doesn't make sense to me that it would be the spark plug or wire since the car will sometimes run for several days without a problem. Performance does not seem to be affected either.

Someone suggested it may be the ignition coil? Any thoughts on this? Also, how would you test the ignition coil to see if it is bad, short of replacing it with a new one?
 
MrElussive

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It could be a bad coil but I think that would just leave you stranded...a bad coil would typically not be working sometimes and not working other times. Have you tried replacing the mass airflow sensor? It should be the cheap and easy to do.
 
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jasonharlos

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Replacing the Air Mass Meter is definitely not the cheap way to go. That part retails for over $350 versus $60 for an ignition coil. My research has led me to the conclusion that a trouble code for the Air Mass Meter does not necessarily mean that there is a problem with that part. There has been many people that have simply replaced that part only to find that was not the issue. I am going to swap out the suspect coil on cylinder 3 with another cylinder tomorrow to see if the problem follow that coil to another cylinder. If that is not the case I'm open to any other suggestions before I go the route of replacing the Air Mass Meter.
 
aNoodle

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That's the same car as me...except I've got 134,000 miles!

I just replaced my six coils, connectors and plugs. I got rid of those square type bosch which apparently they were having problems with. I also went with bosch platinum +4 over the japanese. I ordered the parts from autohaus, great serivce, greater price! I got some new Mobil 5w-40 in there and.....Man, my car is running so smooth now, it's sick. But I don't think coils and all will solve all your problems...may not even be necessary at your mileage. You've change plugs or are you going to the full 100,000? You may want to do that if you haven't already.

I don't know about the P1250. I've never gotten that one. the P1xxx codes are manufacturer specific. But are you sure it means mass air flow? Yeah, that one is expensive to just swap out on a hunch. I've seen this code mean different things. P1250 - Early Fuel Evaporation Heater Circuit P1250 PRC Solenoid Circuit Malfunction P1250 - Fuel Level Too Low.

I think fuel level too low is possibly the issue i have with the car running out of gas with about 1/4 of the tank still full of fuel. I've been keeping it above half for a while now...that's next on my list. I'm thinking it might be the pressure release valve....or maybe I have an air release problem near the injectors.
 
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