1985 BMW 325 DOES NOT FIRE ON 3 CYLS; #2#4 #6

THOMC

MEMBER
1985 BMW 325
6 CYL
2WD
AUTOMATIC
130,000 MILES

RECENTLY BOUGHT WITH ENG. MISS, #2 #4 #6 CYLS;DOES NOT FIRE,
IKNSTALLED NEW PLUGS, DIST. CAP AND ROTOR BUT NO CHANGE. SPARK PLUG WIRES SEEM OK.
NOT FAMILAR WITH BMW'S CAN YOU PLEASE DIRECT IN THE RIGHT DIRECTION.
P.S. THE ENG. SOUNDS SMOOTH BUT LACKS POOP RUNNIG ON 3 CYL'S.

THANK YOU FOR YOUR EXPERTISE AND TIME THOMC

3 Replies

DOCHAGERTY

MECHANIC
9,601 POSTS

If there is spark then the next thing is to check the injectors. Is there power to the injectors? Do they all show the same electrical resistance? Can you swap the injector rails for the one from the old motor?

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Thursday, January 8th, 2009 AT 12:08 PM

FREEBIRDREBIRTH

MEMBER
3 POSTS

The ecm drives the injectors in to seperate sets of three. So maybe one set is not being driven by the ecm, could be the connector. This site shows the wiring but not wich drives wich set. Also you can use a led test light to see the signal from the ecm located in the glove box.

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Sunday, January 18th, 2009 AT 12:44 AM

DOCHAGERTY

MECHANIC
9,601 POSTS

The power flow is from the battery to the main relay, then to all the injectors, to the DME, and then as the "brain" decides how long to open the injectors, it will ground that bank of injectors, and they spray fuel for as long as the DME tells them to. So yes you could have a bad DME or PCM as you call it.

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Sunday, January 18th, 2009 AT 10:10 AM