Alrighty... Just to get a baseline before I start bolting on mods, I had my car dyno'd today only to get really disappointing results. Now, I'm not even sure where to begin.

I'll start with the basics. I picked up the '07 GT/CS a little over a month ago. Other than a Hurst Short Throw and Pypes Mid-Muffler system, it doesn't appear to have any other mods (still) installed. There was an SCT badge affixed to the dash, but I've since removed it. I have no idea whether there's still a tune loaded though.

Since purchasing the car, I've added the wheels and had it lowered. The car currently has approx. 25k miles and seems to run very well.

My issue is with the resulting dyno numbers:



Is it just me, or does something seem really off? If I'm correct in the fact that a stock GT should be ~267 rwhp, I'm almost 50 hp short. Not to mention that this occurs at ~3600 rpm and only goes down from there. You'll also notice that I'm running very lean. The up-curve of my a/f ratio nearly matches the down-curve in power as the rpms increase.

So... This is probably a complete noob question, but where the heck should I start? Since I have no idea whether the previous owner had a tune on the car and left it there after removing whatever other mods they may have had, I'm contemplating having the computer reflashed but don't want to waste the ~$100 if there's a better starting point.

 

I"m a noob as far as the tune's go, too, but I think getting a new stock tune put back on by the dealership might be the first best thing you can do.

You are correct. The stock GT is usually somewhere between 264 and 268. Here's mine before and after I added a C&L Racer CAI..

 

......

 

Where did you get this car from? Anyway I'm not concerned about the HP number, your A/F ratio is HORRIFIC!!! Is this a reputable dyno shop? Do they use an exhaust probe and if so when was the last time they replaced it?

 

So you had the car put on the rollers just to check the numbers? Why did they not adjust the tune after the given results?

 

it is low.
you can start with the easy stuff. plugs, injectors, etc.
how long have you driven the car?
any CEL's?
at WOT, any stumbling or hesitation?

 

Yuck. I'd suspect the dyno and have it redone elsewhere before going to the effort and expense of replacing parts.

 

Woah!
What shop did you take your car to?

This way others can steer clear of it!

 

Ditto...

 

Definitely still has the stock intake.

I bought the car from a dealership. My initial inspection, the dealer's inspection (I know, not totally reliable), and the Carfax all checked out.

Reputable? Not entirely sure. I've done SEVERAL searches for Dyno testing/tuning in Las Vegas and didn't come up with much. This shop didn't have any negative reviews and was close to my work, so I went for it since I was only "testing".

Definitely used an exhaust probe. I watched the whole thing from setting the car up on the dyno to take down. I was totally flabbergasted with the results.

I've only been driving the car a little over a month. Regarding any stumbling or hesitation, that's the weird thing. It drives GREAT. No problems whatsoever - at least that's the way it "sounds and feels".

The testing was done at Sin City Performance, in Las Vegas. Couldn't find anything negative online or any other reason that would lead me to think a simple testing session would be a bad idea here.

I really appreciate everyone's input here. Thanks so much. First thing tomorrow, I'm going to have another testing session done at another dyno in town to compare notes. If they're similar... I'm replacing fuel filter and pump along with injectors. If that doesn't help, computer reflash it is. Hope this is resolved soon. Would really like to start adding power - from the right baseline that is.