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Catholic Power
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Discussion Starter #1
I have recently put new plugs, MSD wires, air filter, water pump, thermostat and changed all fluids in my truck. BUt seem to be getting about 50 miles less out of a tank of gas....

My new wheels are a little hevier than my old 20s but I just dont see that making that big of a difference.


Also this really started to be noticable when I added lucas oil treatment. I thought maybe it was because that shit was so thick. But after changing the oil again and adding a light weight oil it is still doing it.

Any ideas on what else it could be?
 

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Catholic Power
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Discussion Starter #3
You probably got some crappy plugs. Or one might be misfiring. I'd check the ignition stuff first!
Well I got the OE plugs because the old ones werent bad I just figured, at 110,000, I needed new ones. I never had problems with them so I thought that would be the ones to get. They were much more expensive than the others I could have gotten.
 

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did you check the gaps on the new plugs?
 

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Catholic Power
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Discussion Starter #5
did you check the gaps on the new plugs?
Well I didnt do that. I let the mechanic here at the shop do the gap setting. I just put them in. But I was wondering maybe if they were wrong. Thats the only thing I could think of.

What about changing the fuel filter?
 

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AllOffTopic.com FTW!
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Are you sure your fuel economy is less? Have you been calculating your MPG?

Reviewing your list...

New plugs -- since you used OEM, it's definitely not that you asked for the wrong ones. Check to make sure you actually got the proper model with the right gap and such.

Wires -- Still have the old ones? That should be easy to test.

Air filter -- Should be foolproof, but you could double-check the fit.

Water pump -- Was the old one broken? Check to see if the old one spins as freely as it should. If you still have the old one check it. Maybe the old one was moving too freely or the new one is too stiff.

Thermostat -- If the truck was running hotter before/cooler now, that would definitely explain it. That could be caused by using the wrong thermostat, the old one being bad, or the new one being bad. Also, if the old water pump was failing and the truck was running warmer...

Changed all fluids -- You used the specified fluids? Also, did you do filters and screens appropriate to match, and if so were they correct and correctly installed?

New heavier wheels -- Cannot cause any drop in fuel economy unless you're driving like a jerk, racing to every red light just to brake hard at the last minute. Other than that, any energy you put into spinning them up, you get as momentum that keeps them spinning.

Lucas -- Not really familiar with it, but if it's gone I doubt it's to blame.
 

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Catholic Power
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Discussion Starter #7
New plugs -- since you used OEM, it's definitely not that you asked for the wrong ones. Check to make sure you actually got the proper model with the right gap and such.

my mechanic here at the shop checked them before I put them in and said they were good to go

Wires -- Still have the old ones? That should be easy to test.

I chunked them after I put the new ones on.

Air filter -- Should be foolproof, but you could double-check the fit.

Yeah I checked that and it seems to fit tight.

Water pump -- Was the old one broken? Check to see if the old one spins as freely as it should. If you still have the old one check it. Maybe the old one was moving too freely or the new one is too stiff.

The old one still worked. It was just leaking around the gasket. SO I went ahead and changed it while I had it off. And since the thermostat is made into it I went ahead and changed that also. It was not a different degree thermostat.

Thermostat -- If the truck was running hotter before/cooler now, that would definitely explain it. That could be caused by using the wrong thermostat, the old one being bad, or the new one being bad. Also, if the old water pump was failing and the truck was running warmer...

Changed all fluids -- You used the specified fluids? Also, did you do filters and screens appropriate to match, and if so were they correct and correctly installed?

Oil was a little lighter weight because its comming on summer and it gets rediculous hot here in the summer. Or was I wrong and need to get heavier weight?

New heavier wheels -- Cannot cause any drop in fuel economy unless you're driving like a jerk, racing to every red light just to brake hard at the last minute. Other than that, any energy you put into spinning them up, you get as momentum that keeps them spinning.

Well it does take more energy to get them moving though. But these wheels are probablyno more than 10 lbs each heavier. That wouldnt cause it.

Lucas -- Not really familiar with it, but if it's gone I doubt it's to blame
 

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HELL FIRE;3051019[B said:
Oil was a little lighter weight because its comming on summer and it gets rediculous hot here in the summer. Or was I wrong and need to get heavier weight?[/B]
Nope, you were right.

Well it does take more energy to get them moving though. But these wheels are probablyno more than 10 lbs each heavier. That wouldnt cause it.
Right, but that energy isn't discarded. You get to keep it in the form of inertia until you throw it away by braking.
 
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