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Question

Car started misfiring after new starter installation

May 17, 2017 6:02PM PDT

2000 Buick LeSabre. After replacing starter. The car died and had to be jumped. Once the car had enough power it started but now the car runs rough it vibrates alot on idle the rpms are alot higher then they should and they fluxuate often. the service engine light is flashing and I get error codes po300 and po300 P. I replaced half of the 6 spark plugs and connectors (rest are in back of engine and hard to get to) as I though that might help but i don't notice a difference. The exaust has a weird rotten smell and I smell a sweet smell when turn the car on. Also the instrument panel mades a short grinding when the needles are moving after turning key anyway in the ignition.
And that start exactly after all this had happening.
My guess is bad fuel pump or catalytic converter but there are many things that can can multiple engine misfire. Any info you may provide would be greatly appreciated. -jadon

Discussion is locked

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Answer
Both the smell and rough operation.
May 17, 2017 7:15PM PDT
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Answer
PO300
Jun 1, 2017 2:17PM PDT

PO300 is "Random cylinder misfire". The smell is caused by the catalytic converter having to burn unburned fuel. The 'sweet' smell is generally anti-freeze being burned. Both of which will destroy the O2 sensors and the catalytic converter. If the anti-freeze is getting into a cylinder (or cylinders) that could cause the misfire code. Do you notice any excessive steam coming from the exhaust? Your best bet would be to have the cooling system tested for HC's. There is also a chemical called "Block Check"
that you could buy, but is a bit expensive for a one-time use. Any shop with an exhaust analyzer would be able to 'pick up' the HC's if they are there. Did you have any overheating issues prior to the starter problem?