351 SEFI mis-firing - help

[74BroncoCO]

I think my motor is mis-firing. Last time I drove her, it sounded a little funny. I am going to pull her into the garage and turn the lights out and watch for a short to the motor, and then pull a few plugs, but how can I know for certain it is or isn't mis firing? I understand that it could also be the injectors, is there a way to test those? I don't have a Check Engine light, and i would have thought I would have one.

Another possibility is my muffler has some rock rash and could be changing the sound a bit, but I still think I feel a lack in power. I have basic tools, like a tester light and a meter. Any help? Thanks guys!

J.D.

 

[Broncobowsher]

The "How to repair and modify ford fuel injection" book has a good section on diagnostics. One of those is a cylinder balance test. If you do find a weak hole, you can swap parts around (injectors, plugs, wires) and look for the weak hole to move. When you move one part and the power balance show a change to that other hole, you have your part.

 

[74BroncoCO]

Thanks - I need to find that book.

J.D.

 

[SaddleUp]

I think I posted the instructions from it up here at some time in the past. Might try searching for it and see. It's not a bad idea to get that book either but it might get you started a little faster.

 

[SaddleUp]

Here is one of them. I think this is the right one:
http://classicbroncos.com/forums/showthread.php?t=78686

 

[74BroncoCO]

Thanks for the help. Turned out to be real simple (write that one in the record books). I pulled a plug to see what it looked like. Nothing unusual, but in my clumsyness I dropped it and it broke in half. Well I guess I gotta get new ones now. I return with new ones and start to replace them. I get to the third one and when I pull the wire off, I could see a white tarnish on the spark plug head. I examine the wire to find where the insualtion had been damaged because the spark was going thru it and to the exhaust header. So I continue to replace all the plugs and take her for a test drive. Runs like a champ again. Now I need new wires that clamp on better. Most of these were too loose.

What is a good set of wires that won't break the bank? I have Jacobs ignition and I think Jacobs wires (blue in color), but I am not set on those.

You wanna know something crazy? I have never replaced a set of plugs or wires in my LIFE, until now. I do know that I have to keep them straight as the go back in, but I have never had to replace a set. Just funny to think.

J.D.

 

[74BroncoCO]

Btt - Any help on the plug wires? Thanks!

J.D.