Hey;
I'm working on a 97 Lincoln Town Car for a relative, I've got a hesitation that comes and goes somewhat at random. Never happens above about thirty miles an hour. I pulled the codes and got P0305. I know this refers to a misfire in the number five cylinder. The miss has been around several months, she had the plugs changed and it didn't help. It was suggested she try some injector cleaner which she added on Monday, the hesitation "possibly" went away for two days and she noticed it again today. I say possibly because as I said, it's an intermittent problem. I was thinking maybe a coil pack or an injector? My main questions besides what to check is how does this circuit work? Is there a sensor, or does the system read voltages from either the fuel injectors or spark plugs wires. Any help would be appreciated.

 

Bad plug wire perhaps? Have they ever been changed?

 

Yeah, sorry, just got info today. She did replace them but it's been about 50,000 miles. The guy she had change the plugs didn't replace the wires this time because they "looked good". In fact, when I first looked at it, I thought they'd been changed with the plugs a couple months ago because they do look almost new. A guy at work also suggested inspecting the connection at the fuel injector. He said his was doing the same thing and it turned out that one of the pins in the connection came loose. I think I'll try that and the plug wires, then go from there. Thanks

 

Ok, got an update. I replaced the wires and inspected the injector connectors. Found one injector that wasn't completely clipped, but when I pulled it off hesitation got worse and when I plugged it in completely didn't seem to help so i'm guessing it was not the problem. Replaced the plug wires though and so far (2 days now) the hesitation is gone and the check engine light's stayed off. After replacing I found out that when she had the plugs replaced the hesitation went away for three days and then came back. I'm thinking there was corrosion in the connector that got knocked loose when changing the plugs. Will wait and make sure stays gone. Thanks for the suggestion LxMan1, I doubt I'd have asked if the wires were changed, I just assumed they had been.