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Slow decline in mileage

1479 Views 5 Replies 2 Participants Last post by  k5hauler
Truck: 2009 2500HD
Miles: 127K
Mods: none (yet)

I'm looking for assistance in diagnosing my slow decline in mileage. I've been tracking it for awhile as shown on the graph, and I'm trying to determine whether this might be an injector issue or something else. I've been fairly diligent on maintenance and got little assistance from the dealer the last time I took it in. No codes are been thrown, but I may not be seeing everything with my OBDII reader.

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Start by checking your injector balance rates
What's the best way to do that?
What's the best way to do that?
Find a scanner that can read live data like a Tech 2.
It will show balance rate information.

If you do not have a scanner like that just go to a local auto parts store and ask them to plug in and check your balance rates for you.

all Injectors should be within +/- 4.
If you get the info please post it here in the thread
Finally was able to get the truck scanned…will say that the auto parts store either don’t have the capability or will do it unless the CEL is on.

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The truck also came up with a TSB relating to the thermostat.
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