Intermittant misfire

[Big3Tom Harrison]

Our 2004 ST began to misfire while going down the Interstate. All of a sudden the check engine little began blinking, the AC compressor shut off, and the engine lost 400 rpm. This lasted about 90 seconds and then all went back to normal for about 60 seconds and then repeated continually for the 90 miles it took to get home.

We replaced the plug wires with no improvement. We replaced the coil with no change. Now what do we do?

 

[Big3Tom Harrison]

I should add that we got the following codes: P0300,301,305,316.

 

[Scott Tanner]

see codes here...



http://www.mysporttrac.com/~library/16285/OBD%20codes.htm



misfire...



how many miles? if close to 100k, the plugs may be a fault...

 

[Big3Tom Harrison]

It has 82K on it.



I know what the codes are, I think ignition, my son thinks injectors.



We are going to pull and change the plugs.

 

[EddieS'04]

Change the wires also.

 

[Big3Tom Harrison]

It's the consistently repetitive on and off that suggests to me that it is heat related.



Something works until it overheats and cuts out until it cools off. What does that?

 

[Todd Z]

Fuel pump ?? Fuel filter? Spark plugs... air filter.. Or coil...



Todd Z

 

[Big3Tom Harrison]

With the exception of the plugs, all other problems would affect other cylinders, not just 1 and 5.



I thought maybe someone would say "oh that problem, this is the fix..."



I will check fuel pressure and ohms test the injectors. I'll also get a new fuel filter.



Any other suggestions?

 

[shawn stonbraker 2]

Got the same code P0300 and P0302 when my Bosche Platnum Plug gave out in my #3 Cylinder. Ran fine when cold, missed when hot. The plug had actually worn through the insulation at the points. Hope that is all your problem is. What brand of plugs did you have in?

 

[Big3Tom Harrison]

We are taking out Motorcraft AGSF 22PGM original equipment (I'm told)

We will be putting in Autolite Dbl Platinum APP103.



I hope this works as we will be leaving Saturday morning on a 1100 mile round trip to go whitewater rafting.