"Question: if the truck is fully warmed up why would it not ping if the
weather is cold? In the summer it would occasionally ping under heavy load
even with 93 octane"
Possible Answers:
1. When the air is cold, it is denser. A denser air charge will require
more fuel so the mixture might be richer. The reverse is true when the air
is hot; it is less dense so the mixture might be lean. A lean mixture can
cause a ping aka. "spark-knock."
2. The colder weather might be causing the coolant temperature to run a
little lower. Since a lower temperature coolant will extract heat better
from the heads, this could also cause it not to ping when it is colder.
I've been reading all the pinging stuff. A lot of factors could cause
this, some of which have been discussed.
I'm starting to wonder about where the heads are manufactured for these
vehicles (differences in valves, chamber volume [compression ratio], metal
composition [specific heat]), possible differences in fuel injector
manufacturers (spray pattern & volume), computer differences (spark advance
curves, etc.), fuel quality by location (low octane [85], do they use
oxygenates in the fuel [MTBE], atmospheric pressure by location (high
elevation effect), sensor differences (the computer reads a variety of
sensors [MAP, EGO, TPS..to name a few), etc.
I wonder if there is a way to figure out where the engines in these trucks
were manufactured and then plot engine plant versus pinging?
Just some SWATs (scientific wild-a$$ed thoughts....).
Hope this helps.
Mike
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