Odd AFM Transition

[Snakey]

Charlie,

Every now and then when my engine is transferring from AFM to all 8 cylinders i get what almost sounds like a knock or "dieseling" type noise. Maybe a stalling type noise would be more accurate? I hope this gives you some kind of an idea on what the sound is. Any ideas?

Thanks Man!

-Ryan

[G8GT721]

maybe if your more specific, does it only happen when your cruising down the highway, or also at slow speeds. Can you feel anything when you think afm happens and or when you hear the noise

[-Ray-]

It's the Pypes.

[G8GT721]

It's the Pypes.

i bet thats it, i forgot afm make exhaust sound terrible

[GRRRR8]

Odd sounds are common with muffler/exhaust changes when in AFM mode.

[boomer]

Just sounds like knock. its not that uncommon to hear audible knock on the transition from 4 to 8 cylinders. There can be a sluggish delay when when you start to accelerate and it transfers back to 8 cylinder mode. this is where most knock can be heard. This is also easily seen with any logging software.

Your exhaust will make the AFM transitions louder and more noticeable, but should not cause knock/knocking sounds.

Just another reason to disable AFM IMO :)

[Snakey]

Just sounds like knock. its not that uncommon to hear audible knock on the transition from 4 to 8 cylinders. There can be a sluggish delay when when you start to accelerate and it transfers back to 8 cylinder mode. this is where most knock can be heard. This is also easily seen with any logging software.

Your exhaust will make the AFM transitions louder and more noticeable, but should not cause knock/knocking sounds.

Just another reason to disable AFM IMO :)

This is kind of what I was thinking but thought I'd ask the resident experts for more advice!

It seems to do it when applying throttle inputs so I'm guessing its more noticeable due to the exhaust but really is annoying when it sounds like its going to stall out and quit for an instant then comes right back. Such a quirky car we have!

[norm8332]

You could just disable it with a tune and be rid of it. It's only good for 1-2 mpg anyways.

[Snakey]

That's what my plans are but still undecided on what tune I want to go with. I like the Cortex with being able to change it back to stock if need be, but I think I'd feel more confident having someone who knows tuning doing their thing with it.

[-Ray-]

You can go back to stock with Vector's Powerflash as well.

[G8GT721]

That's what my plans are but still undecided on what tune I want to go with. I like the Cortex with being able to change it back to stock if need be, but I think I'd feel more confident having someone who knows tuning doing their thing with it.

Vector and Livernois, have the remote tuners which are great. I know that with Vectors you can update & return to stock with ease, im sure the same goes for Livernois tuner

[johnh]

x2 on the Pypes making the AFM noises audible.


It's only good for 1-2 mpg anyways.

On the highway I have seen 3-4 mpg (22 vs 25-26 averages), although my AFM tune is a little more aggressive.