New guy with a tech question

Maximumoverdrive · January 18, 2006

I just replaced my 96 Chevy 2wd extended cab with a 2002 GMC SLE exteneded cab truck. My new truck has a 5.3 and man what a difference in power, I love it. I'm also involved with GM high performance cars as well. In june of 05 I traded my 01 Camaro SS for an 05 GTO and absolutley love it. I know my cars inside and out as well as the truck I had. I do all the needed work myself andt works out most of the time but, I have been known to shot myself in the foot on a couple occasions.

Anyway, on to the questions of which I have 2.

1) How similar are the 5.3 and the LS1?

I know the basics like iron block vs aluminum but, what about inside.

2) Why does my truck seem to be getting worse mileage at every fill up?

I bought the GMC used about a month ago with 66,000 miles. I've filled up 3 times so far and I've gone from 17.5 to 17 to 16.5 and I don't know why. I haven't driven the truck any different then any other time but it still keeps going down. The air filter is new and the plugs look alright so I don't know. I'm a little concerned because I was excepting to get better fuel mileage with the new truck but, I was getting a consistant 19mpg out of the 96 Chevy.

Anyway it's great to be here. I've been reading the site for a few weeks now and just decided to stop in.

Thanks for your help.

Wingnut · January 19, 2006

Count your blessings...I average 13.9 mpg in my 02.

Seriously though...Guys here have reported worse mileage than mine, and other have reported as high as 19-20mpg.

Not sure about it rapidly deteriorating like that though.

Maximumoverdrive · January 19, 2006

I was talking about it yesterday and was told that the feulmileage could be caused by carbon build up. I have heard about this before and of people "decarbon" the intake. I always thought it was BS but maybe there is something to it.

Anyone else heard of it? The truck I bought was driven by and older guy. It had a campershell on it and not a scratch in the bed. Could it be the truck was babied too much allowing excessive carbon build-up.

99silveradoz71 · January 20, 2006

You could probably find plenty of information by doing a search for Seafoam or Top Engine Cleaner. Both have been used by forum members to deal with carbon and such.