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I am having this issue on my 2011 Buick La Crosse. The mechanic changed the coil and spark plug on this cylinder (cylinder 1), all seemed well for about 300 miles then the car misfired again on the freeway and the engine light went back on.
The mechanic now says this cylinder is intermittently misfiring. He put fuel cleaner in the tank and will test drive it. If it were a fuel problem, wouldn't that cause all the cylinders to intermittently misfire, not just cylinder one?
If it were a fuel problem, wouldn't that cause all the cylinders to intermittently misfire, not just cylinder one?
Thanks in advance for any info or advice.
Yes, a fuel problem would cause, most likely, a misfire on more than one cylinder. It could be an injector, but it should throw a code for an injector, at least my wifes LaCrosse did. What was the code?
Technical Service Bulletin # PIP4924D: SES Light And Misfire With Injector Codes - (Jan 21, 2014)
Carefully inspect the fuel injector wiring harness for rub through or internal wire opens.
Some common spots are against the intake plenum, at valve cover bolts, against the fuel line and on the side of the head under the plenum.
If this concern is found repair or replace the injector harness as needed.
Technical Service Bulletin # # PI1296: Diagnostic Tip for Engine Misfire and/or Popping Noise on Cold Startup after Cylinder Head or Fuel Rail/Injector Repair - (Aug 19, 2014)
This may be caused by improper orientation of the fuel injectors due to the previous repair. The injector spray pattern is not in a circular shape, but an oval shape.
An improperly installed injector redirects the ends of the oval spray pattern into the intake valve during valve overlap in the split pulse mode of a cold start. Once the split pulse injection start up process has completed it's duty cycle, the engine will operate normally until the next cold start event.
Are the replacement coil and plug OEM? Many cars are finicky when it comes to ignition parts. Also check for oil on the spark plug. A leaking spark plug well o-ring may cause oil to seep into the well and foul out the plug.
Reasons for misfire (in general, not specific to this model buick)
Bad spark plug
bad coil
bad wires (if applicable)
bad/clogged fuel injector
damaged fuel injector wiring
low compression in cylinder
oil leaking in cylinder
excessive rich or lean condition in cylinder
Yes, a fuel problem would cause, most likely, a misfire on more than one cylinder. It could be an injector, but it should throw a code for an injector, at least my wifes LaCrosse did. What was the code?
I believe the code indicated only misfire of cylinder one. PO301
I believe the code indicated only misfire of cylinder one. PO301
The nice thing about misfire errors is that parts can be swapped into a different cylinder. Basically, you know the plug, injector, coil, etc for cylinder 2 is good. Use these parts for cylinder one and see if the misfire continues. Then put the cylinder 1 parts into cylinder 2. Does the code now show misfire in cylinder 2? You get the idea.
Could have misread the cylinder order and replace plug/coil on the wrong cylinder.
The injector is certainly a suspect.
How old is the fuel?
Did he give you the code #?
Fuel is sold as "top tier" by local gas station and I use premium grade. I refuel often as I travel a lot (mostly highway) and the gas station is very busy.
The code is PO301. The mechanic claims the misfirings continue on cylinder one at a very low rate and now, in addition sometimes, on cylinder 2 at a lower rate than cylinder 1.
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