'07 Silverado w/ Active Fuel Management???

[badassl79]

Hello everyone,

I have a '07 silverado (new body style) with a 5.3 and it has the "Active Fuel Management" and I am considering installing a cam and I am wondering if doing this will affect the "AFM". Or is this just a program in the computer that activates this??? Does the engine vacume affect it as well? Any input would be a great help!!!

[highroller]

Good Question... I think the AFM goes hand in hand with the PCM or tune you get for your truck. I can tell you after I got a custom tune from Magnacharger my AFM no longer is active.

[badassl79]

I am still waiting for a return phone call from Nelson Performace about this subject, but the breif call that I did place with them they did ask me if I wanted to retain this. Which leads me to believe that I can keep it, but I would really like to know if I end up putting a bigger cam in (nothing too crazy! yet) will the lower vacume from the engine affect this at all??? Is this controlled strictly by the computer? Or does it work in conjunction with the engine and the computer together???

[ducky]

I am still waiting for a return phone call from Nelson Performace about this subject, but the breif call that I did place with them they did ask me if I wanted to retain this. Which leads me to believe that I can keep it, but I would really like to know if I end up putting a bigger cam in (nothing too crazy! yet) will the lower vacume from the engine affect this at all??? Is this controlled strictly by the computer? Or does it work in conjunction with the engine and the computer together???

There was I think one guy from the RGV that had a white truck like yours that may be cammed, or he might be running spray, and I dont think I saw anything about him having to do away with the AFM. I dont know if that helps lol sorry

[Z71chev]

I believe there are special lifters or something on the 4 cylinders that de-activate.

[VMAXNY]

I have a o7 vmax with a Nelson tune and Allen turned off the AFM on my truck it runs great. I took a road trip the other day and still got 16.7 MPG. The system is just a hydraulic lifter system. I am also searching for a cam i am probably going to go with a lunati voodoo set up.

[badassl79]

I have a o7 vmax with a Nelson tune and Allen turned off the AFM on my truck it runs great. I took a road trip the other day and still got 16.7 MPG. The system is just a hydraulic lifter system. I am also searching for a cam i am probably going to go with a lunati voodoo set up.

I drove my truck to Denver from Lincoln NE a few weeks ago, which is 498 miles and I made it on ONE tank of fuel!!! (23.7) mpg. I would like to retain the AFM while running a bigger cam if that is possible??? I would really like to know how far I can go with this 5.3 without losing the drivability??? Cam, intake, throttle body, headers, tune, converter with nitrous?????????? Already have the converter and the nitrous!!!

[rutroe]

I just recently had a 212/216 cam put in my 07 Z71. Truck hasn't missed a beat with AFM still active. My understanding was that the "fuel charge" just stayed in the cylinder until the cylinder was "activated" again. The dealer told me the same cylinders are deactivated every time...of course, the dealers tell you lots of stuff.

[-HIC-]

Below is how it works...

"In order to deactivate a cylinder, the exhaust valve is prevented from opening after the power stroke and the exhaust gas charge is retained in the cylinder and compressed during the exhaust stroke. Following the exhaust stroke, the intake valve is prevented from opening. The exhaust gas in the cylinder is expanded and compressed over and over again and acts like a gas spring. As multiple cylinders are shut off at a time (cylinders 1, 4, 6 and 7 for a V8), the power required for compression of the exhaust gas in one cylinder is countered by the decompression of retained exhaust gas in another. When more power is called for, the exhaust valve is reactivated and the old exhaust gas expelled during the exhaust stroke. The intake valve is likewise reactivated and normal engine operation is resumed. The net effect of cylinder deactivation is an improvement in fuel economy and likewise a reduction in exhaust emissions."

Given the list of future mods you listed the converter will have the most negative impact on fuel milege when it is not locked up. The cam will come in second, and as long as you do not go radical you will notice little drop in mpg at highway speeds. Depending on the cam you will loose more mpg in city condition and when combined with the converter loss this could be a good bit. Once on the highway and the converter is locked up you will be ok. The other mods you listed could be considered gas savers, although this will likely not be the case given you will be on the pedal alot more with all the extra power!

Hope this helps.
Bryan

[badassl79]

Brian,

This is by far the best information that I have received yet!!! Thank you sooo much for your time and help. It is greatly appreciated!!!