Misfire problem

Nicholg2286 · 02-26-2018, 12:39 AM

2007 328i.

Started misfiring yesterday. Wife started car and noticed engine was missing. Miss is present immediately, at idle and thought RPM range although smoothes out as RPM rises. I checked code and found P0304. Reset code and upon restart, same code appears after 60 to 90 seconds. I have tried swapping the coil from #4 with the one from #3 to see if DTC would follow. It didn't. Plugs look good, dry, not burned. Compression test good range from 190 to 210. Tried swapping fuel injectors from #4 to #5 = no change. Tried running car with #4 coil disconnected to compare with how it runs connected = no change. Did voltage check. 12.5v at underhood connector for jumping and had same voltage at injector. Very afraid this might turn into a DME issue because I don't do computers...

Any other ideas? Getting desperate! Thanks

RocketSurgeon · 02-26-2018, 01:44 AM

I might check the grounds and wiring, and perhaps try a new bosch coil. Otherwise you might be looking at a DME. You could pick up a used one for well under $100, and have it synced up for under $250.
If you suspect a DME problem, you might crack it open and test the MOSFETs. The MSD80 is known for that problem, it's possible that your MSV80 could have a similar issue. Mosfets are really cheap, just find a phone repair shop to solder them for you.

02-26-2018, 12:39 AM	#1
Nicholg2286 Registered 0 Rep 2 Posts Drives: 07 E90 / 09 E92 / 01 E46 Join Date: Feb 2018 Location: Sacramento CA iTrader: (0)	2007 328i. Started misfiring yesterday. Wife started car and noticed engine was missing. Miss is present immediately, at idle and thought RPM range although smoothes out as RPM rises. I checked code and found P0304. Reset code and upon restart, same code appears after 60 to 90 seconds. I have tried swapping the coil from #4 with the one from #3 to see if DTC would follow. It didn't. Plugs look good, dry, not burned. Compression test good range from 190 to 210. Tried swapping fuel injectors from #4 to #5 = no change. Tried running car with #4 coil disconnected to compare with how it runs connected = no change. Did voltage check. 12.5v at underhood connector for jumping and had same voltage at injector. Very afraid this might turn into a DME issue because I don't do computers... Any other ideas? Getting desperate! Thanks
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02-26-2018, 01:44 AM	#2
RocketSurgeon Lieutenant 264 Rep 459 Posts Drives: 2008 135i Manual, CBR650F Join Date: Jan 2017 Location: NC iTrader: (0)	I might check the grounds and wiring, and perhaps try a new bosch coil. Otherwise you might be looking at a DME. You could pick up a used one for well under $100, and have it synced up for under $250. If you suspect a DME problem, you might crack it open and test the MOSFETs. The MSD80 is known for that problem, it's possible that your MSV80 could have a similar issue. Mosfets are really cheap, just find a phone repair shop to solder them for you.
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