george88gta

iTrader: (3)

I know this has been discussed a lot, but I need to make a quick decision on what to purchase. Car is an 02 Trans Am conv. Basically stock LQ4, pcm retuned and has traction control. Gets 20 mpg around town an 25+ on the highway. Plenty of acceleration for a daily driver with the original 2.73 gears. Posi is going and it is developing a clunking sound so I plan to rebuild a rear axle assembly over the winter and swap it in. This way I can keep the car mobile while I gather parts, rebuild,etc. I have a decent deal on a used rear end assembly ( complete) but it has 3.23 gears. Question is how much of a hit will I take on MPG and can I retune the PCM with my Tech II or do I have to send the PCM to a tuner?

redbird555

iTrader: (14)

sounds like your city is pretty rural 20mpg in REAL city traffic isnt happening even on a full moon lol. anyway the 25mpg figure seems realistiic for hwy. With that said gears will help your "city" mileage out a bit at the expense of the hwy... although with a modest gear swap to 3.23's i doubt it will be noticeable really. the 3.23's are a pretty good gear so you'll be happy with those as they'll reall ywake the car up but i'm not sure if the tech II can do the change.... if anything you may just be able to swap in a stock 3.23 gear tune if your car is stock

george88gta

iTrader: (3)

Yeah, I live in the "sticks". May even get blacktop next year. Just kidding, but it is rural, a few stop signs and maybe 2-3 traffic lights. No city blocks and stop signs around here. Anyway, I dont need any more acceleration, but if the swap isnt going to be a big hit on mpg, then it looks like going to the 3.23's will save me the expense of getting a new set of 2.73's. I will look thru the TECH II books, but I may just have the PCM reprogrammed by a tuner. They did a nice job programming for the LQ4 swap so I am comfortable with their work. Thanks for the response.

FirstYrLS1Z

iTrader: (4)

typical real-world freeway MPGs for an A4
2.73 - 25.9
3.08 - 24.7
3.23 - 24.5
3.42 - 24.0
3.73 - 23.0
4.10 - 22.2
4.56 - 21.5

george88gta

iTrader: (3)

Sounds like it isnt a big deal for a daily driver. Anyway, next decision is to try and reprogram my self or hire a tuner. Thanks for the info.

01ssreda4

iTrader: (96)

3.23 if the deal is good, 3.73 if you are paying full price.

george88gta

iTrader: (3)

Deal fell thru, shipping was more than the cost of the parts plus a 4 hour drive. So back to looking. Thanks for all of the help.