Misfire issues

jculley14

New member
3
0
1
Buick Ownership
2007 Lacrosse CXL
I have an 07 lacrosse cxl. P0300 random multi cylinder misfire code. Changed the ignition control module and all 3 coils. When I pull the wires one at a time from coils, all cylinders have spark. Please advise me on what to do next. I'm desperate because I need this car for work
 

ulycyc

Active member
405
201
43
Long Island, New York
Buick Ownership
1987 Turbo Buick, 2001 Park Ave Ultra
What about the sparkplugs, vacuum leaks ? Don't pull plug wires and see if you have spark. That can blow out the coil and or module. We use to do that 40 years ago but don't on any newer cars. Use a inductive clamp, pocket tester or scan tool.
 

TX LaCrosse

New member
8
6
3
DFW
Buick Ownership
LaCrosse
Other issues can cause a P0300 misfire not just ignition. Check for vacuum leaks, air intake/plenum leaks. Check fuel pressure for faulty injector(s) and harness connections.
 

jculley14

New member
3
0
1
Buick Ownership
2007 Lacrosse CXL
Other issues can cause a P0300 misfire not just ignition. Check for vacuum leaks, air intake/plenum leaks. Check fuel pressure for faulty injector(s) and harness connections.
Thank you. I changed all the plugs, checked for leaks, and it still doing the same thing. Not sure how to check fuel pressure. (Side note) It runs great at idle but not when you try to give it gas.
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02LTD

Active member
100
63
28
Long Island NY
Buick Ownership
2002 Lesabre Limited
Thank you. I changed all the plugs, checked for leaks, and it still doing the same thing. Not sure how to check fuel pressure. (Side note) It runs great at idle but not when you try to give it gas.
Exactly HOW did you check for vacuum leaks?
 
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