A number of years ago there was a couple of threads where a bunch of our guys were fussing with a bunch of Camaro owners from Australia, and they were bragging etc. BUT the guys down under claimed fantastic MPG…after much talk and figuring things out it was discovered that there was a Easter egg they called a “Lean Burn Cruise” setting and theirs was turned on and ours was not.

So once we got them turned on the USA Cars also got great MPG something like 30/35MPG.

I have run search after search and cannot find these old threads.

Is there a special section for OLD threads??

Can you help me???

Thanks.

Rich

 

"What your looking for" site:thirdgen.org
Type that into google replacing terms or phrases in the quotes.
Also try highway mode.

 

Thanks that was real help lots of threads...

 

The Australians might be using Imperial gallons, not US gallons. Makes their mileage number look fantastic when it is really no better than ours.

 

As I remember it they did a bunch of number crunching and once they had it all balanced out then declared: OMG that is 35MPG...

And once they found the Easter Egg and was able to turn it on and the US guys also got 30/35 MPG.

Rich

 

Pretty sure if there was a magic switch it would be common knowledge by now.

 

A majority of the 3rd gen EFI ECMs have a lean cruise mode. I didn't check all of the code masks that were used. The '88 - '92 TBI ECMs have a lean cruise mode. Some early calibrations have it enabled. GM stopped doing that after Ford got fined by the EPA for the same thing. It is considered an emissions defeat device (NOX increases).

The '89 MAF cars have it in mask $6E.

The '90 - '92 TPI & MPFI cars have it in mask $8D (TPI) and mask $88 (MPFI).

It is easy to enable as GM usually used the minimum MPH and/or the minimum CTS to disable it.

And yes, getting 32 - 33 MPG is possible.

RBob.

 

If your search doesn't provide satisfactory results, try searching "Highway Spark and Fuel Mode" or HSFM" instead of "lean cruise" mode. That's the more common name for it, and there is, in fact, a lot of discussion on it.

 

OMG there is TONS of info...

THANKS.

Rich