Re: Miss at Idle

Posted by Gary On 2013/3/5 21:08:17

Drew,
You didn't post the mileage on the engine although in this case I would say it doesn't matter with that kind of compression numbers. In park or neutral, is the miss obvious at the tail pipe and is it steady? does it decrease as RPM's increase?

In the past when I've experienced a slight miss at idle and I've pretty much eliminated the usual suspects including air/fuel mixture, I simply pull out a pair of insulated plug wire pliers and start pulling off one plug wire at the time, observe how the engine reacts, then reinstall the wire and move on to the next one. In your case the miss should be more obvious on the cylinder that's already slightly missing to begin with. Once you've determined which cylinder is the likely culprit then you can start determining what's causing it. Try swapping the plug wire for that cylinder with one of the others and see if the miss relocates accordingly. There could be carbon build up under one of the valves or maybe a broken or weak valve spring but at least you know which cylinder to focus on.