Yesterday, I changed my spark plugs and wires. The wires were replaced with the same as before, but for the plugs, I went from Bosch platinum 2 plugs to Champion coppers. The truck runs as smooth as ever, but it seems that my fuel economy has suffered. With cruise control set at 50, the overhead computer would vary between 17 and 21 mpg. Now at the same speed, the computer varies between 16 and 18 mpg. Could it be that the old plugs were better? or are there any other suggestions of what could have caused this?

 

That's probably from a heat range change.

Also, what did you set the gap at?

IMO, you did good by getting away from the bosch crap....

 

You need to do yr mpg's long hand. I think it would be the other way around.

 

I kept the old plugs in case, but I think I will try to run the plugs a little longer to see if there is any change.

 

Did you disconnect the battery when you installed the plugs?

If you did, you reset the PCM and it runs rich for about 200 miles or so before the adaptive learning leans out the fuel trims correctly.

 

No. I havn't disconnected the battery since I cleaned the throttle body last week. I've probably driven close to 200 miles since.

 

i noticed a little less mileage and a little less power when i switched off of my bosch platinum +4s to the truck plugs, then i took those out and put the champion platinums in. all three are the stock heat range.

you need to check your mileage by resetting the trip meter when you fill up then the next time you fill up divide the miles driven by the amount of gas you used.

ie: 275 miles divided by 21.5 gallons = 12.79 mpg.

 

......

 

Oh yeah, forget the brand names, it's not that important, but what matters is you went from
a high performance double platinum plug down to a standard copper core one, there's less
conductivity hence your spark isn't as strong and the end result is a slower or less complete burn.
It all happens in a flash, but in time-lapse photography the stronger the spark, the better.

Them 2x platinums don't cost $4 each for no good reason
But you might try Autolites instead of Bosch, I think they might be a little cheaper.

 

A few dollars per plug isn't a huge concern to me. The reason I switched to Champions is that they are recommended by the service manuel, but if some other plugs work better, I have no problem with switching again.