I ran a can of seafoam through my silverado tonight and Saturday I'm going to put the new plugs in.Then I''m going to change the fuel filter just to make sure. I'll get another can of seafoam and put it in the tank.

Next question...
Im not sure when I'm going to install my cam and buy headers.
Would I be better off having the computer tuned for now? Then having it retuned again after I install the cam and headers?
Or the other option would be to buy a programmer like Bulleydog.
I wont be doing anything for a few moths I'm just trying to do my homework before I spend my money.
Thanks

 

A lot of tuners will redo it for free a second time

 

Thanks for the heads up. That will probably be my next upgrade.

 

We I have changed the plugs. Ran Sea foam through the intake and a can in the tank. I have replaced the fuel filter and the solenoid. I am even trying 89 octane gas.
My mileage went down to 12.8 average on 3 fill ups.
Anything else I can check. Thanks

 

Both are lying to you...

 

Maybe the guy I bought it from is off, but my buddy isn't. I've seen him get 100,000 out of an 80,000 mile Goodyear. His drive is 95% highway 60-95 miles one way.

 

I could see 22 mpg on a 4.3L with 3.42 or less. Just doing the math it works out

 

I was referring the his MPG numbers, aint happening in a V8 full size truck unless his commute is downhill both ways.

 

Not trying to get a fight started here, but I wouldn't call someone a liar because of their claim to mileage. I had an 03 Yukon XL 5.3L and 4.11's. 13 MPG at 40MPH and 13 MPG at 60MPH, but if you drove 55MPH on the dot, she would give back 22MPG all day long. That is hand calculated, not trusting the dash. I would get on the road for a trip and just set the cruise and let people pass me. 18.5MPG pulling 2000lb trailer empty, 16.5 MPH pulling loaded on the return trip.

Pic of the return trip


Stock 265/70R17's on escalade wheels 4.5/5 drop, custom dual exhaust with cherrybomb muffler, CAI, and a gutted MAF. Otherwise, stone cold stock.

 

Best I ever saw out of my 2001 4wd ECSB was 17, and that was one time on a trip back to Phoenix from up in the mountains, so downhill. I was usually around the 12-13 mark no matter what, city or highway. I got 15 going from Phoenix to LA at 70mph on the interstate. Towing I would get about 8 mpg. Could never figure it out or fix it.