I just took my dog for a walk,now my 2000 century 3.1 is missing code p0301,cyl #1 misfire.I had backed in uphill at the dog park,walked her 15-20 mins and came back,car started,but was missing.ses light started flashing.got home scanned,code p0301.looked at wires(pretty new),no sparks or clicking.of course #1 is on back side.have not pulled plug yet.its always been a real good runner.

We live in upper Michigan,was cold for most of winter,now warmer but 37 out today.I am thinking water in gas,slug of water was probably picked up and sent to #1 injector?. added gas dryer,and injector cleaner,drove 10 miles.still missing.150.000 on car,never had any problems before.I remember a few tankfulls back, some snow on gas nozzle at gas station but,just a little bit.too cold that day 0 degrees f. I was cold and in a hurry to get back in car.

any ideas?....drive it a few more miles maybe?....hoping someone in the rust belt can help....thanks,rich.

I've had a sparkplug fail straight out of the box backing out of the driveway. So don't knock something just because its fairly new.

Situations like this where you can move parts to see if they follow is good. Swap plugs with #2 and see if it happens. No change? Swap the wires. Last thing to try would be swap injectors, but that can be a bit involved.

I would also look closely at the sparkplug when pulled, as that will give you an idea if anything major is happening in the cylinder.

My gut has me wanting to jump straight to the nasty scenarios, but let'* take it one thing at a time.

"looked at wires(pretty new)"....really means nothing....

Some wires can have thousands of miles on them and look good.....

First thing I would do is check #1 and #4 wires....they share the same coil......could have carbon tracking between plug and boot.....could have a corroded terminal at either coil terminal(carbonned up from arcing).....could have a bad plug......could have a bad coil(need to check spark output with a spark tester)......bad wire.....

Are you losing coolant? #1 cylinder is known for head gasket problems....

Swap the injector with another hole and see if the problem moves.

Please Note the date of the post you are replying to. Most of the time, the OP'* haven't been on in years and more than likely won't respond.
Please do not bump threads older than 6 months, Thank You.
See site rules re: bumping old threads : https://www.gmforum.com/introduction...-first-304557/
Thread Closed.