Random Misfires
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Random Misfires
I have a 05 Bonneville SLE with a 3.8 and I just started getting the Service Engine Soon light, I check with my ODBII reader and it just tells me "Random Misfires" I have 83K mile on original plugs, but would a O2 Sensor cause this or a Cam Sensor? I can drive the car, but it has NO Power and smells as if the brake pads are burning, but they are not. If it is the O2 sensor, Im not sure which one it would be.
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Thanks.
#2
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Umm, just so you know, the 3800'* are know for engine fires because of oil leaking from the front valve cover, dripping down the 1,3,5 sparkplug wires and onto the hot exhaust. I wonder if the smell your smelling is the oil burning up your plug wires causing the misfire??
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#3
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could be coils, wires, plugs or the crank sensor among other things. id do the plugs wires and coils. just general maintenance stuff anyway.
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Misfires
I replaced the Plugs with AC Delco Platnium with AC Delco Wires, and it is still misfiring. All the wires are dry, and do not have any oil on them, plus I use Mobil 1 Full Synthetic Oil, which has a higher burn factor. I suspect the Cam Sensor, which is throwing the timing off, but I never replaced one on the Series II, I replaced it on a Series I Supercharged, but never on this series II, what do I need to remove for the Cam Sensor, the Water pump?
#5
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ive never had to replace a cam sensor. why do you think the timing is off? i would test the fuel pressure and sniff the vacuum line on the fpr for gas (if you smell it its bad) it could be coils, icm, low fuel pressure, bunch of other things
#6
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I replaced the Plugs with AC Delco Platnium with AC Delco Wires, and it is still misfiring. All the wires are dry, and do not have any oil on them, plus I use Mobil 1 Full Synthetic Oil, which has a higher burn factor. I suspect the Cam Sensor, which is throwing the timing off, but I never replaced one on the Series II, I replaced it on a Series I Supercharged, but never on this series II, what do I need to remove for the Cam Sensor, the Water pump?
Stick to the more common failures before you get into the cam sensor. If you replaced wires and plugs, I would check fuel pressure next. Have you changed the fuel filter in recent history? If not, change it. If that doesn't clear things up have the fuel pressure tested to see if the fuel pump is failing.
The other possibility is a bad ignition coil. Sometimes misfires on two cylinders will read as random misfires. Here is a link to a write up on how to check the coils:
https://www.gmforum.com/trouble-shoo...-wires-278818/
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