RE: ACTIVE FUEL MANAGEMENT

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RE: ACTIVE FUEL MANAGEMENT

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Chevrolet >> Chevy Trucks, Vans & SUV's >> Silverado >> RE: ACTIVE FUEL MANAGEMENT

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RE: ACTIVE FUEL MANAGEMENT - 7/21/2007 9:09:59 PM

dhblack

Posts: 18
Joined: 6/15/2007
Status: offline

I traded a perfectly good 04 Silverado LT extended cab 5.3 engine with the heavy duty tow package (3.73 rear end)
I was getting average mileage of 17.5 to 18.6 This included intown driving and some road (interstate miles) I needed more room so I foolishly thought with the AFM on the 07's I would come close if not exceed my old mileage. I bought an 07 Silverado crewcab LTZ with the 5.3 AFM 3.73. I am lucky if I get 13 miles per gallon! I'm driving easier on the same roads and routes I did before. I'm lucky if I get 15 on the road. What could be wrong??????

(in reply to zirmar)

Post #: 11

RE: ACTIVE FUEL MANAGEMENT - 7/21/2007 9:29:21 PM

Fireguy8

Posts: 56
Joined: 4/26/2007
Status: offline

I just got back today from a trip that was combined interstate/2 lane hwy back road. My 07 Silverado 5.3/3.73`s with AFM got 18.6. It has averaged 16-17 mixed has I live slightly out of town. For me this is an improvement has I sold an 91 GMC that was a good truck,[5.7/3.42`s], but did not get quite that fuel mileage.

< Message edited by Fireguy8 -- 7/22/2007 11:35:19 AM >

(in reply to dhblack)

Post #: 12

RE: ACTIVE FUEL MANAGEMENT - 7/22/2007 12:32:50 AM

Norton Nork

Posts: 5
Joined: 7/21/2007
Status: offline

The first 1000 miles on my 07 with AFM is 18.3 mpg.

(in reply to Fireguy8)

Post #: 13

RE: ACTIVE FUEL MANAGEMENT - 7/22/2007 11:36:17 AM

Fireguy8

Posts: 56
Joined: 4/26/2007
Status: offline

Remember to check your fuel cap.Mine has gotten loose already once and that affects your mileage.

(in reply to Norton Nork)

Post #: 14

RE: ACTIVE FUEL MANAGEMENT - 7/22/2007 1:53:21 PM

kcb37

Posts: 504
Joined: 7/3/2006
Status: offline

Something else to think about is that while it is engaged only four of the cylinders are getting fuel so you save gas. But the other four are still their moving to, because of the engine still having to move the other four cylinders it will rob power from the engine to keep them going. So your gas mileage will suffer from that view point. The question is do the four running cylinders have enough power to keep all eight moving without using the same amount of gas in the long run.

(in reply to Fireguy8)

Post #: 15

RE: ACTIVE FUEL MANAGEMENT - 7/22/2007 3:59:53 PM

matador

Posts: 98
Joined: 7/5/2006
Status: offline

Ok, I will bite. What does a loose gas cap do to affect mileage?

_____________________________

Matador

2006 Chevy Silverado Z71 5.3 4x4

(in reply to kcb37)

Post #: 16

RE: ACTIVE FUEL MANAGEMENT - 7/23/2007 10:36:28 AM

ZX1100F1

Posts: 2433
Joined: 8/1/2006
Status: offline

Since the valves are deactivated during 4-cylinder operation the dead cylinders produce virtually no parasitic power loss and you can easily see (on the DIC display) the enhanced MPG as the engine transitions from 8-cylinder to 4-cylinder mode.

A loose fuel cap will not effect fuel economy or engine performance but it may trigger a "Service Engine" light on the IP.

(in reply to matador)

Post #: 17

RE: ACTIVE FUEL MANAGEMENT - 7/23/2007 11:50:52 AM

Fireguy8

Posts: 56
Joined: 4/26/2007
Status: offline

Not being an engineer I do know that in theory the fuel cap will not have much effect other than allow excess air into a closed system which will as stated above throw a service engine light.

(in reply to ZX1100F1)

Post #: 18

RE: ACTIVE FUEL MANAGEMENT - 7/23/2007 1:45:05 PM

ZX1100F1

Posts: 2433
Joined: 8/1/2006
Status: offline