GDawgA4

Went to get GIAC'd today...WOW, what a difference over stock. I love it! So much more pull in all the gears, especially 3rd, 4th, 5th and 6th on the roadways and freeway!! Power delivery is very smooth, feels like a V6 now. It just up's and goes, I'm over the speed limit b4 I even know it!

Question though...dunno if this is normal or not. When in 4th, 5th or 6th and around 3k RPMs, if I hammer it down, I get this "rumble" sound/ever so slight feel up in the front of the car. It sounds like the car going over those rumble strips on the side of the highway. Is this normal? I'm not sure if I'm explaining it right or not :-/

But anyway, love it so far!

swz

very nice!

fourwheelslide

I believe that's a little clutch chatter...pretty normal when you chip our cars.

mattb2003

Question about that - does that put a lot of extra wear on the clutch?

Diztek

yes, just dont floor it above 2nd gear if your rpms are below 3200

fourwheelslide

It's the load on the clutch at those low RPMs that give you that chatter.

GDawgA4

Hmmm...but its happening at 3k+?

B'more 1.8tQMS

I have a similar situation with my car which is Upsolute chipped. From what my friend who is very experienced with WRX's and turbo cars in general told me, this is because the new (i.e. more aggressive) chipped fuel map is requesting more fuel than the pump and injectors can supply. Accordingly, the ECU cuts fuel and it makes that groaning sound. This seemed like a reasonable explanation to me, especially since the clutch has not seemd to chatter to me at other times (not like it makes any torque at 2000 rpm anyway). There is another side to this explanation too- if you accelerate quickly by pushing the throttle JUST short of all the way down, the car seems to go faster than putting it on the floor. My friend also offered his fuel explanation for this saying that some ECU's spray LESS fuel at WOT to save wear on the engine from overzealous leadfoots. Anyone heard similar stories to this? It sounded too compelling to be complete BS and he has owned several chipped cars (Subarus and Audis) so I tend to believe him.

GDawgA4

down. I was just trying out mashing it down to see how the pick up was after chipped, therefore experiencing that sound/feel.

But your friend's explanation does seem reasonable and logical. I'm very happy with the pick up of the car without mashing it down anyway now =D

bhvrdr

There are dozens of people who have done this. MTM notified me of this situation back when it was thought it may be bushings. The greatest amount of torque load is at about 2800rpm and that is where you get the noise. If you shift higher you will not get the noise. This noise will happen with injector programs that run rich if you have the stock clutch so it is clearly not a fueling issue. My car runs 14:1 at idle, 12.5:1 at mid rpm and 11:1 at redline. cheers! Mike