PCM
 

I see that some here have an Intense PCM, or such, installed. I had considered this as a mod, but was worried that it would cause my shifting to be harder and be rough on my tranny. Since I am just a street driving man(albiet spirited) with a very rare trip to the track, I don't want to beat up my car since it's a daily driver.

Outside of possibly doing a little on my exhaust, I was not planning on doing anything else as far as mods. However, if the PCM makes my car more efficient, wakes it up a bit, and tunes it up without causing excessive wear and a lot of loss in gas effeciency, then it is an option to consider.

The pcm really does not add that much power but it does raise the shift points, not as much as a shift kit but you do feel it. I would think the quicker shifts would help perserve the tranny though, as the clutches are slipping a lot less with the quicker shifts?
In order to take advantage of the higher shift points though you need to beef up the valve train or else you may get valve float and a drop in performance.
Most consider this mod to come last as it does more with raising limiters and shift points than a performance mod?

A lot of people get the PCM when they change to a smaller pulley, which is totally fine.

But personally, I think if you are going to get the PCM, then upgrade the valvetrain a bit, with better springs and pushrods, and maybe even a nice set of rockers. That way you can be sure that you can handle the higher shifting. Just a thought.

Since I don't plan on doing all those things, it is probably best I don't get the PCM. Thanks for the info. 8)

What is valve float and why is it bad?

Definition: A high-rpm engine condition in which the valve lifters lose contact with the cam lobes because the valve springs are not strong enough to overcome the momentum of the various valve train components. The onset of valve float prevents higher-rpm operation. Extended periods of valve float will damage the valve train.

I googled it...

Good question.... I was wondering as well. :lol:

basically what that means is ... the valves are trying to move so fast the springs can't keep up and the valves can't actually close.... how is this bad?... well it's bad on many many levels

1) if your valves aren't closing EVER .. your not getting full compression and your kicking fuel and air down your exhaust and exhaust up your intake (think NASTY valve overlap)

2) if you've got a very tight valve to piston tolerance .. and your valves aren't closing all the way... piston + valve = BAD

3) this is the most usual thing that happens... you've created a gap in your valve train from the cam allll the way to the valve... so now allllll the other stuff is slapping and bouncing to make up for that gap... it's a really good way to mushroom lifters and bend rods amoung other things

But what are some effects to the car, like how is it noticeable?

Go up to one of your friends, and give them a really hard slap. If you did it right, that is what you would hear with "piston slap." That was just an example, and a poor one at that. Trust me, if your piston was hitting the valves.. you WOULD hear it.


-justin

Keep in mind I am a total nub. I take all these threads, put them together, and try to understand how cars work :roll:

From what I am hearing, valves open DOWN pushing into the cylinder?

That would coincide with what I heard earlier that if a valve is open, and a piston reaches TDC, it could bust right through the cylinder essentially blowing it up.

Has my ecclectic knowledge pointed me in the right direction?

at that speed of RPM it would sound like someone Dropped a hand full of screws into your intake ... yes you would hear it

and piston slap is more the piston hitting the cylinder walls ...also not a cool sound at all either

I don't think a stock 3800 would smack the valves to the pistons on valve float ....but if it ever happened... trust me you would hear it... I've witness'd it first hand...

basically if it does happen your car will fall on it's face power wise .. and your valve train will sound WAY out of adjustment ... or out of oil (if you've ever heard an oil starved valvetrain)

basically your definately hear it if you go into full valve float ... and if it ever happens... you'll know .. you'll cringe.. and if the expensive noises don't go away when you get off the throttle.. you'll cry cause you just bent somethin

That even SOUNDS painfull just reading about it! :cry: :shock:

Valve float can cause the car not to shift at wot because the engine can never get to the rpm needed to shift.

Forgive my noob question, but what does WOT stand for? :oops: I've seen it used a lot, but haven't figured it out yet.

wide open throttle (WOT) I found it!!!!

Very good young padawan...

...but you're not a gearhead yet...

Yes, but the force is strong with me...... I promise I'll return and complete my training.