have a 2007 sport trac with v-8. 92k check engine light comes up with premature spark, firing issues. Note light will go off for a couple of days after towing boat (4000 lbs with trailer) Dealer changed plugs at about 77k, coil has been replaced on noted cylinder. lifter that one side seems a little noisy.
Engine light started coming on intermittantly after spark plug change, but has been pretty much on with the exception of after towing, but comes back on after about 100 miles. I have been running synthetic since about 12k, can't quite figure this out. HELP emmision testing due soon

 

The synthetic is OK.

What fuel are you using, Octane?

Sounds like you may have some pre-ignition! Carbon build up in cylinder or bad plugs (heat range)... Philip

 

What type/brand of plug was installed?

 

Is the code you are getting for a misfire (PO030x where 'x' is the cylinder number) or something different? I've not heard of a "premature spark" diagnostic code.

-Rod

 

it is a misfire code, seems to run ok, but possibility of some mechanical noise (place screwdrive in that area you can feel something is off, like I said coil hads been replaced

 

The miss fire will account for that noise, Do some testing/diagnostics, dont continue to guess..

Back to the question of the plugs, what do you have in there??? ... Philip

 

My local tire place has recommended I take it to ford, I will check the basics, cinnections etc thanks