My gas mileage seems to be shot. I now average around 10-17 mpg (combination city and highway driving. I used to average around 17-26 mpg (combination city and highway) prior to getting the mods installed on my 2002.

relevant mods: Blackwing, performance coupler, WCC cold air screens, Corsa Indy exhaust, cags defeat.

I did the idle relearn.

I'm wondering if the air screens could be having a negative affect on my mpg by causing some erratic air flow to my air filter. I've noticed my INST mpg seems very erratic while slowing decelerating instead of a smooth change, and it drops down to close to 1-5 MPG while accelerating hard.
I don't recall my '99 behaving like this.

Any ideas?

 

Targa, for what it's worth: I have the mods in my sig installed and I currently get 31-33 MPG on the highway cruising at 70-75 MPH in 6th gear. I believe my city/highway is around 23 or so. I'm mostly on the highway so the city/highway quote may be off somewhat, but I concur with you, it seems like your MPG is somewhat low.

On a side note. How has everything else come out with your exhaust and all? Did you get it all straightened out? How about the rest of your mods, are they all finished and installed properly? Keep me updated. Thanks.

 

Something wrong there, those mods should help in anything???

 

After having a few mods done on mine (PRT's, CAGS, Blackwing) my mileage decreased, but that was because I kept my foot in it more than before.

If you are driving it at similar revs, I would think if there is any change in mileage, it would be better, not worse. I don't know, but have never seen another post indicating decreased mileage with cold air screens. Best of luck!

 

Ive got that stuff and am geting much more than that

 

Probably the Billet Aluminum Shift Ball! :lol: :smash: :D

 

I get 31/33 on the highway.. and 18/20 in the city...
the mods you have should not be a problem,,, My opinion is your driving habits have changed.. like somneone said.. you are In it more... or maybe drivng in too low a gear.. I some times find myself... under certain conditions.. putting my car in a gear to: jump to light speed:"keeping it in the torque curve.. eg. I am on the interstate doing 70 taching 1200 rpm.. OH MY GOD just off idle.. but I see somne traffic and some weavers.. so i down shift to fourth get in the sweet spot..just in case i gotta get out of someones way..

 

TargaC5,

I don't see how any of the mods you have installed would decrease the efficiency of the engine.

If you have recently done the mods, do an idle relearn and drive the car allowing it to completely learn the new program.

Also, you may be driving the car harder than you normally do or just hard. This alone will greatly decrease the efficiency of your engine.

Shawn

 

Thanks for the replies. I think it might be the CAGS defeat. I know that's caused my shifting to be different than pre-mods. Yes, I have to admit that I've been opening her up a little bit more to hear the Indys ROAR!!!!!!!!!!!
Okay, maybe there's nothing wrong, but I'm still not sure.
What about the erratic instant MPG on no-braking deceleration?
I'm going to get them to diagnosis my computer when I take it in on Saturday morning to get them to drain some of the oil out.

C5Noir, when I picked up my Vette last time, they had just installed the new exhaust. The check oil message came on when I started to leave their parking lot. (It never came on prior to me dropping it off. And, I still had I think around 70%+ oil life left.) I talked to the service advisor. He checked it and it looked low. I asked him if it was a quart low. He told me 2 quarts. So, I bought 2 quarts on the way home and filled it. Well, two days later, I checked it in the morning (cold, sitting overnight) and the oil was way above the max line.)

I called yesterday and they're going to drain some oil to make sure it's at the proper level, then they're going to start the oil consumption test.

I wonder if this could be related to my really low MPG???

 

:D :D :D
Yeah... that thing is really heavy. :cheers:

 

TargaC5, was your car sitting on an incline or anything? If your oil is somewhat near the "low" mark you'll get that message and it will go away after a few start cycles. That may be what happened and they overanticipated the amount really in the engine. I hope they didn't foul out your plugs putting too much oil in there.

 

Good advice. I'll get them to check the plugs.

Thanks.

:cheers: