1999 Suburban K1500 5.7L 4L60E , I am experiencing spark plug fouling and as with my Ford lightning, I am curious if increasing the heat range will help my Suburban burn the fuel more efficiently. I live at 6000 ft and travel 150 miles round trip in the surburban daily. This solved the problem in my Ford Lightning, Sentra SE-R and Ford Bronco.
Also does anyone know what the number of the current heat range and the next higher heat range would be? And what are the best spark plugs you guys have found for these engines.
Thanks in advance for any and all advice and help.
Tim

 

When you inspect the spark plugs are they dry or wet?
Do they foul to the point that the engine will not run?

The Electronic Engine Management system on your 1999 is suited for elevations well above the 6,000ft that you operate, if you are fouling plugs something is not exactly right either too much fuel or burning oil or not a powerful enough spark.
A hotter plug may mask the symtoms of problem by burning off the fuel or oil but it would be better to address the cause.

Test the plug wires, make sure they all are less then 30,000 ohms.

 

Maybe you have a faulty thermostat and the engine isn't getting hot enough.