[Longshot270]

If Im just wanting to view the data I logged on pegasus, do I need to worry about setting my truck back to stock? I havent been having much luck when my gryphon and computer get together so I want to make sure before I do it.

[Longshot270]

Ok, well I figured since pegasus is just viewing information then its ok. Turns out it is ok. After looking at the graphs I really started to understand how the engine and tranny work power wise. One thing I dont get is why the spark advances more during regular driving and barely moves when I get on it.
3.7 degrees advance regular driving and .5 to 2.1 when pushing it. Am I reading this correctly because its just not making sense to me? Any of you tuners know whats going on?

[JackandJanet]

Originally Posted by longshot270

Ok, well I figured since pegasus is just viewing information then its ok. Turns out it is ok. After looking at the graphs I really started to understand how the engine and tranny work power wise. One thing I dont get is why the spark advances more during regular driving and barely moves when I get on it.
3.7 degrees advance regular driving and .5 to 2.1 when pushing it. Am I reading this correctly because its just not making sense to me? Any of you tuners know whats going on?

I'm not a tuner, but I'll hazard a guess. When you "get on it", you put the engine under great load. This increases the chances of detonation. Advancing the spark then would only increase that potential.

At cruise, or even normal acceleration, the tendency to "ping" is not so great and the spark can be advanced to promote more thorough burning.

No, let's see who's the first to poke holes in my hypothesis!

- Jack

[Longshot270]

Originally Posted by JackandJanet

I'm not a tuner, but I'll hazard a guess. When you "get on it", you put the engine under great load. This increases the chances of detonation. Advancing the spark then would only increase that potential.

At cruise, or even normal acceleration, the tendency to "ping" is not so great and the spark can be advanced to promote more thorough burning.

No, let's see who's the first to poke holes in my hypothesis!

- Jack

That makes a lot of sense to me, we'll see if anyone else has any input. Guess Im just kind of suprised to have a record of this kind of stuff for once.

[Power Hungry]

Sounds like the scale is off in the viewer by a factor of 10. The 2.1 to 3.5 should be more like 21 to 35. The .5 subsequently would be 5.

When an engine is under load, the timing is reduced significantly to reduce detonation from the higher cylinder pressures caused by ingesting larger amounts of air on each stroke. Most folks don't realize just how much timing is removed.

[Longshot270]

Originally Posted by Power Hungry

Sounds like the scale is off in the viewer by a factor of 10. The 2.1 to 3.5 should be more like 21 to 35. The .5 subsequently would be 5.

Ha ha oops. Should have seen that right off the bat, but I'm having to learn how to use 3 different graphing programs right now. Pegasus, MS Excel and JMP.

Originally Posted by Power Hungry

When an engine is under load, the timing is reduced significantly to reduce detonation from the higher cylinder pressures caused by ingesting larger amounts of air on each stroke. Most folks don't realize just how much timing is removed.

Cool, looks like JandJ is a pretty good guesser.

[Longshot270]

Another question about this kind of stuff.

First time I messed with MAF readings, the results of idle readings were lower without the snorkel (if that is the piece that connects the filter casing to the fender well on the 4.6L) than with it in. Is this what makes some trucks run lean with a CAI? It was also on two different days so that could be a reason the results do not match the one I did after it.

So I tried it again on a different day.

While sitting in a parking lot I let the truck idle in park. I recorded a total of about 5 minutes, first without the snorkel, then I put the snorkel on and because it was really long so I let it stick out from under the hood, last I replaced everything to stock. After looking at the graphs and numbers, without the snorkel the MAF read a little higher than stock and a lot more steady. With the snorkel sitting out side of the hood, everthing ran rough and became unstable. I was there so I know that nothing got sucked in. Then when I clipped everything into its stock locations, the MAF sensor readings were still not as steady as the "without snorkel" idle.

Opinions or ideas?

[JackandJanet]

Again, somewhat of a guess. If you remove the snorkel, you are essentially doing a "Gotts" mod. You make it much easier in my opinion, by a factor of about x4, for air to be brought into the engine.

But, you don't really change the environment around the MAF sensor, so it should not make the truck run lean.

Now, why more air should allow the engine to idle slower, I cannot explain. And, I can't really figure out any reason for it to rum more poorly with the snorkel simply out of the engine bay vs having it in the fender well.

Was there possibly any wind blowing that might have caused turbulence in the intake with the snorkel out of the engine bay?

Whatever the reason, sounds to me like a "Gotts" mod might be a good thing to do.

- Jack

[Longshot270]

I'll actually be trying the gotts mod later on today if I can find a piece of 3 inch pipe. Last time I went, Lowes and some of the other hardware stores didn't carry anything in that size.

[JackandJanet]

Originally Posted by longshot270

I'll actually be trying the gotts mod later on today if I can find a piece of 3 inch pipe. Last time I went, Lowes and some of the other hardware stores didn't carry anything in that size.

You might look for the "armadillo" looking metal "flex" pipe. Other members have used it and it distorts easily enough so it fits into the fender. However it's rigid enough that it won't "pucker" like the rubber end that was used by kd2rs. Looks to me like it would be an easier way to do this mod, but it's a bit more expensive.

- Jack