GOT a van!

Changed the spark plugs today. Had a few random misfires according to the scanner. I could not tell when driving as it's smooth running engine.
The old plugs were shot!. Almost all the gaps measured .075 to .085, One measured .050. Did not drive it after the change so i' ll see how it runs tomorrow.

Hell yeah, that will help out. Haven’t posted much in this thread but I’ve been keeping up on it. Glad you got a van and stuck around.

What were the new plugs gapped to? .060" is better than .075", but they really ought to be down closer to .050". I run .045" with the blowers in the trucks.

fancyTBI said:

Hell yeah, that will help out. Haven’t posted much in this thread but I’ve been keeping up on it. Glad you got a van and stuck around.

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Well i was wondering if i should or not after selling my suburban but after thinking about it the van is more or less, mostly a GMT 400.

Supercharged111 said:

What were the new plugs gapped to? .060" is better than .075", but they really ought to be down closer to .050". I run .045" with the blowers in the trucks.

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The new plugs were gapped at .060. I have messed with plug gaps on the same 7.4l before and did not see any real difference so i just left em alone.

Some systems are set up that they have to have a certain number of key cycle misfires before will set a code. Fords have large misfire counts before CEL.

The misfires were so few that in my experience, it never would have set a code.

Drove it to work and home with a little town/hwy driving.
Nothing changed. Still idles the same (smooth) starts the same and feels the same driving. Im sure new plugs have helped something, what though, i dunno.

Been awhile after changing the plugs and it did improve my mileage. Went from a solid 19 mpg highway to 21.5 highway.
It still has the random misfires, but i notice once warmed up to operating temp (199.4F Scanner) there are no misfires. LFTF is still running around +8 to +14 ish with STFT running near 0 to +3 ish.
I can not find a vacuum leak anyplace.
I also suppose that driving around with spark plugs that had a gap of .080 and a bad cap/rotor for who knows how long maybe the coil could be weak?. I do have a brand new one i might try swapping in.
Maybe after 280K and what looks like original O2 sensors they could be the problem? They do seem to be work ok though except every couple weeks i'll get a Heater circuit code on the B2S2 sensor. Clear the code and it takes a few weeks to pop up again.