Gas Milage Gone To Hell!

[hoorders]

Hey everyone,

 

The last month or so it seems like my milage has gone down the toilet.........my truck is 2000 silvy 1500 SBEC Z71 Auto with the 5.3.

 

I've never really calculated my miles per gallon but gauge it by how much its costing me to get to work and back. I drive 130kms round trip to work and back......I used to be able to do it for around $15 worth of fuel............I know the price of fuel makes a difference to the amount you actually get but lately its costing me around $22-$25 to go the 130kms..............gas costs havn't gone up that much in the last few months.......they were probably 95cents a litre when it was costing me $15 and now its $1.06 per litre.

 

Any thoughts????...............if this keeps up I may have to get rid of the silvy.

 

[ridnlow]

have you changed the fuel filter lately?? any SES lights??

[hoorders]

have you changed the fuel filter lately?? any SES lights??

I changed the fuel filter not too long ago and no SES lights...............Maybe the oxygen sensors(before cats) need replacing?.............if they are bad do they cause that much of a decrease in milage??

 

Thanks!!

[Schmids5.3l]

Spark plugs? I'd check the simple stuff.

[hoorders]

Spark plugs? I'd check the simple stuff.

I did NGK's and taylor wires about 30k ago.................I suppose I could put another set of plugs in.................the truck seems to be running fine though.

[Shaners]

I'd replace the air filter (if needed) and clean the Mass airflow Sensor.

 

The EGR valve is another simple thing to check/replace...

[frdfandc]

Its not the oxygen sensors. If they are bad, the check engine light would turn on. You can't guage fuel economy by how much you spend. If that is the case, mine is in the toilet. Spent $57.00 last stop, next stop wil be over $75.00 U.S dollars.

[redvett]

O2 Sensors will get lazy as they get old and after 100000mi its recommended to replace them. They will not set a code as long as they are working for emission compliance but fuel economy isn't going to set a code.

[hoorders]

I'd replace the air filter (if needed) and clean the Mass airflow Sensor.

 

The EGR valve is another simple thing to check/replace...

I cleaned the the mass air flow sensor, blew out the air cleaner and I want to clean the EGR..................is the EGR that cylyndrical looking thing at the front passanger side of the engine?...........it has has a tube(about 1 inch in diametre) going from it to the engine.

 

Thanks.

[jhm]

This is crazy. Before you start replacing parts, calculate your mileage for a couple of fill ups.

[redvett]

If the EGR isn't working correctly you will get an SES light. EGR does not affect fuel economy it cools the combustion cycle and spark detonation.

[Bish]

O2 Sensors will get lazy as they get old and after 100000mi its recommended to replace them. They will not set a code as long as they are working for emission compliance but fuel economy isn't going to set a code.

 

Agree completely. Before I replaced the upstream o2 sensors, my mileage dropped almost 2mpg with no check engine light. The tank after replacing them immediately went up by 2mpg.

 

Also agree you should calculate mileage for a while before you spend and $$$. I actually have a spreadsheet that I track every tankful (190K now). I can tell you the exact tank they change to winter blend based upon the drop in mileage.

[Triki_Dick]

I've started on my 07 NBS Sierra clocking mpg and my new truck is only getting between 15 + 16mpg fullstop. Highway or town! I'm a little worried but I only have 2k miles on it now.

 

I was hoping it would run in by now.

[Draenor]

+1 on calculating your mileage..(or is it kilometerage.... ) The next question is, are you getting fuel at the same station? They could have a bad tank of gas. I would try a diffefent station. Remember on you log note ;which octane gas you getting at what station and where.

 

Edit* you havent done ANY modifications to you truck recently have you?

[redvett]

I've started on my 07 NBS Sierra clocking mpg and my new truck is only getting between 15 + 16mpg fullstop. Highway or town! I'm a little worried but I only have 2k miles on it now.

 

I was hoping it would run in by now.

 

Dont expect any better fuel economy or less oil usage until you have abot 12000 miles on your vehicle. Take that long to get it broke in completely.