ebruce2

iTrader: (1)

I've been noticing this more since I got my L-Tuned exhaust, due to the acoustics.......but does anyone else experience this???

I'm will be rolling down the highway at about 70mph or so, punch it, and listen to the "tune" of my exhaust and motor. I get up to around 80 or so, and as the motor revs continuously higher, it sounds like it partially stays at the same rpm (or even lowers a bit) and then picks back up again more dramatically. What the hell is this????

I'm confused.

Vlad_Stein

You're comparing engine sound (loudness?) against your tach's rpm reading. You assume that the sound and rpm are 1-to-1 related. This may not be true. You have a modified exhaust and you're going 80mph, plus god knows what other factors are involved (wind, road surface, etc.) Go by less subjective criteria (G-tech, may be, against another GS without the L-tuned).

Also, you can do a Dyno session and see if the power drops off at speed/rpm point you're talking about.

ebruce2

iTrader: (1)

Vlad - I'm sorry, I didn't properly explain my experience. I actually was keeping on eye on the tach and one eye on the road the last time I did this. The tach actually dipped back very slightly in tandem with the sound difference that I heard. For that reason, I guess I kind of did associate the two events

I wish I knew of a shop with a dyno around here.....I would be there in a second.

So what do ya think????

BTW, thanks for the help.

Eric

Vlad_Stein

Hey, Eric!

OK! So you're saying you're going ~70 and then you gun it and listen / look at what happens.

This is one scenario:
When you're driving on the highway, you TC is locked (to keep rpms down and fuel economy up).
When you gun it, the TC is unlocked (to let the motor rev higher, down-shift, etc.). Then as the TC "hooks" up (the vane builds up pressure), your rpm go down slightly because there is more load on the engine.
So, to take this theory to its logical conclusion, after this initial "slipping" the revs should climb relatively evenly.

I wonder if someone else who is more technical than I could second that or refute it.

Unfortunately, I don't know any dyno places (I am not that far in my mod quest yet ). If no one else gives you more pointed info, try and drive another GS and see if it does the same.
Also, try to reset you ECU (to "un-learn" the shifting habits of the tranny). Try Power-mode and see if that makes it better (I am not sure if that influences the TC, but it does influence the tranny).

Let us know if you find something.