Have a 1995 Aerostar 3.0

Recently noticed an intermittent misfire in #1 cylinder. Seemed to primarily occur after reaching operating temperature. Assumed burnt exhaust valve and figured I'd just drive it til it wouldn't drive any more and scrap it. Today, after having not been driven in almost a week, the misfire occurred when the engine was cold and is now persistent. I am now thinking I have a faulty fuel injector.

I rented a compression tester but it's too cold and dark right now to mess with. I did, however, probe the 1, 2, and 3 fuel injectors with my multimeter to check resistance. Sure enough, 2 and 3 are fine, but 1 gives nada.

I went ahead and ordered the fuel injector because I felt pretty confident, but now I'm second guessing and am curious if anyone has any input.

Thanks, y'all!


EDIT: Took to auto parts store and had a scan done... results said no faults. CEL not illuminated.

 

You could further verify that you have a faulty injector by pulling its electrical connector, like testing a spark plug, and see how the engine runs without it. If the misfire doesn't change, then you've positively identified it.

 

Thanks for the reply xlt. I had pulled the spark plug and left it plugged into the wire to verify spark when I first noticed the issue. Then as you said I unplugged the fuel injector and there was no change. That didn't necessarily rule out a dead cylinder, though. I just finished the compression test a few minutes ago and that cylinder is definitely good to go. I ordered the fuel injector yesterday and it was supposed to be in today, but just an empty box came. Looks like I'll have to do it tomorrow if the weather cooperates, since I don't have a garage.

I know I'll have to take the upper intake off to get the fuel rail out, will I need to replace any gaskets or anything in the process? It's nice that the injector that went out is the easiest to see and reach, but what a bummer I still have to take the whole thing out!

 

Yes, unfortunately, changing an injector requires removal of the fuel rail, which means removing the upper intake manifold, and disconnecting everything from it first. Fel-Pro makes an intake manifold gasket kit that as all the gaskets you'll need for this.

Watch the PCV valve; mine has a plastic nipple that cracked when I tied to pull the rubber hose off of it.

 

Just wanted to update that the Aerostar is back up and running. Wasn't as difficult or time-consuming as I anticipated. Only ran into a couple mishaps: lost one of the vacuum plugs when pulling the upper intake out, and a separate vacuum leak developing after reinstall.

After about an hour of searching around under the hood for the lost cap I found it on the floor behind me XD

The leak was because I forgot to plug the hose from the pcv back into the throttle body.

If I had to do it over, I'd tag all the vacuum lines and even write it down so I'd know how many I disconnected and reconnected.

Thanks for the help xlt4wd90!

 

Congratulations on a job well done. Hope you have many more happy miles.