stngh8r

I'm looking to buy a Impala SS. The primary purpose of this vehicle will be a DD appliance. That being said I want the best MPG possible using regular 87 octane.

According to fueleconomy.gov the 06-08 is spec'd for premium and the 09 for regular.

SO, what is the difference between 06-08 and 09? Is it just the tune? If so will a custom 87 tune get me fixed up if I end up with a 06-08?

Thanks in advance
Eric

08 pimpala ss

Well its only the 06-09 that comes with the 5.3 the 10-11 come with a couple choices of v6 the 12 comes with 3.9 witch has nice power and a 6sp trans and the 5.3s hate 87 unless tuned for it and u will only see 16-18 in town if u keep your foot out of it and 24-28 highway fully stock

stngh8r

As a GM fan and overall gearhead I am embarrassed I messed up on the year models, guess I was mixing up my car research.

Anyway, I have edited my OP to clarify my original question and re-researched fueleconomy.gov.

neilownz

Some people have done flex fuel tunes. I run premium because I get knock codes when I don't.

LS1 Racing

iTrader: (15)

NEVER use 87 in an LS4 car. I don't care what that government website says. You will not get better mileage and you'll suffer reduced engine power because the PCM will be constantly pulling a ton of timing because of knock. I've said this countless times before, but after driving around in an LS4 car for the last 5 years with a scan gauge set to monitor knock, I can tell you that 91 octane on the stock tune results in a lot of KR. No, you can't hear the knock unless it's really bad, but it is there, and over time, is damaging to the motor.

Yes, you can get a custom tune for 87 octane, as I tried at one time, but it took a lot of fun out of driving the car. As far as differences between 06-08 and 09 are concerned, there really aren't any. Like I said above, that's an error on the website. The only minor difference in LS4 W-body drivetrains is between 05-06, which had the E38 PCM and 24x crankshaft reluctor wheel, along with a separate TCM. The 07-up cars have the E67 PCM with the 58x reluctor wheel, as well as an internal TCM. That's it. There are no other differences between the engines and calibration for the same model over the different years.

There's only been once V6 selection each year since 2008, which is the 3.5. The 3.9 was killed because nobody bought it and it got similar mileage to the LS4.

The 2012 and 2013 cars got the 3.6 DI DOHC motor.

Again, forget about what the feds say!

fieroguru

iTrader: (1)

05-06 use the E40 ecm (24x = Gen 3) with an external TCM (I don't know the model #)
07-up use the E67 ecm (58x = Gen 4) with an external T42 TCM

The E38 ecm is a 58x Gen 4 ecm

91parkave

iTrader: (4)

Too add on E40/67 both are gen 4 software and both use T42 transmission controller .

LS1 Racing

iTrader: (15)

I stand corrected! Thanks for setting me straight!

MC06SS

Do you have 250,000 miles on your SS yet LS1 racing?? I know you put a TON of miles on that sucker!! How is the TEP holding out?? I am at 96K on the orig tranny in my Monte (yes, I know I am living on borrowed time)

LS1 Racing

iTrader: (15)

We're up to about 230,000 now. My wife got a job closer to home, so instead of 1000 miles a week, it only gets about 600.

TEP trans is still hanging in there with no issues, and we've got 140,000 on it. We're probably going to keep the car another year or so, or until something major goes wrong. It would be pretty cool to get it to 300k, but I just don't see that happening in the time we plan on keeping it.