My 1993 f150 with 302 V8 has been miss firing and bucking. The problem started six months ago with just a little missing in overdrive while climbing hills. Then it started any time it was under a load condition. It’s gotten progressively worse and now I need to downshift into low gear to climb any hills. It’s got 111,000 miles (most of which is short trips).

I’ve replaced the coil, MAP sensor, and plugs. Wires, distributor cap and rotor are only one year old. I’ve separated the #7 and #8 wires, so it doesn’t seem to be a cross-fire problem. But, the number 5 through 8 wires and coil do seem to glow neon blue in the dark.

I ran a self test and got codes 31 and 131. Code 31 is "EVP circuit below minimum voltage". I couldn’t find what the 131 code is for.. It doesn’t seem like low voltage from the EGR would cause this type of misfire problem. I checked the EVP and the sensor side had only 500 ohms (when it should have been 5,000).

The vacuum hoses all seem to be in good condition. I’ve also checked the wiring harness at the ignition module for shorts.


Could this be something in the distributor (like the Stator sensor)??
Could it be the Ignition control module$$$$?
Could it be a warn timing chain??

I’d like to give it one more chance before giving up and taking it to the professionals…

Any ideas would be apriciated..

 

you off-spring of steve83??

Brice

 

if it is glowing in the dark get new wires
and maybe get these too plugs distributor cap and rotor

 

Did you test the originals by the book? Did you test the new ones?That's not how you prevent crossfiring.

No, you're not reading the codes right. It's not possible to get 2- AND 3-digit codes from an EEC. Read this thread.It doesn't sound like you're testing it correctly.It could be anything. You need to test the ENTIRE ignition system at one time by the book without replacing anything until it fails the test. If you replace something, start testing again from the beginning, and continue until the whole system passes. Use the procedure in the Haynes manual & any cheap digital multimeter. It doesn't matter right now if the engine runs perfectly - just get the ignition system to pass so we can cross it off the list.

 

The wires, cap and rotor were replaced less than a year ago.. Is this a common problem on the 302 engine?

 

i dono about the 302 but i replace everything about 10,000 or a year
i got everything for about 85-100 bucks and kept the old stuff for a spare


And listen to steve83 he has got good advice
thanks steve83

 

It was the wires!!!

Bricelittle gets the gold star..

Thank you Steve83 and Bricelittle for your imput. I replaced the wires tonight and its running great... The wires don't sparkle and now the coil dosn't glow. Hopefully the old wires didn't damage my new coil. I'm surprize the other wires only lasted 16 months and less than 6,000 miles.

Thanks again
Steve93

 

Must have been cheap aftermarket wires.