tuning for better mileage
Burning Brakes
Joined: Apr 2004
Posts: 762
Likes: 2
From: Huntington ma
Adjust the fuel tables so that you are Always on the lean side of the BLM's (carefully - not Too lean). Adjust the timing tables to be crowding the knock sensor about All the time. Fiddle with the TCC lockup stuff (assuming it's an automatic) to lock up sooner/earlier and Unlock later. Getting the idle RPM's Down as low as possible, Etc.
You mean like That?
Sure. Why wouldn't you? There's a couple of MPG, on average, in there from what might be considered a "better" performance tune - mostly in where the BLM's end up.
BTW - running higher octane gas (93 as opposed to 87) means a bit more timing in there most of the time which results in another mpg or so, average. For the .20 per gallon difference at the pump it's worth it..
Also - taking the 255's off and putting the 225/65-16 snow tires On gets me another 1-2 mpg. At least it does until the gas stations around here start pumping the "winter" blended stuff, and the numbers go back Down until spring.
You mean like That?
Sure. Why wouldn't you? There's a couple of MPG, on average, in there from what might be considered a "better" performance tune - mostly in where the BLM's end up.
BTW - running higher octane gas (93 as opposed to 87) means a bit more timing in there most of the time which results in another mpg or so, average. For the .20 per gallon difference at the pump it's worth it..
Also - taking the 255's off and putting the 225/65-16 snow tires On gets me another 1-2 mpg. At least it does until the gas stations around here start pumping the "winter" blended stuff, and the numbers go back Down until spring.
Instructor
Joined: Oct 2000
Posts: 152
Likes: 0
From: des plaines, il
Depending on the year, GM bins include a 'lean cruise' routine in the basic
ECM program. It was not EPA-approved, so it was not activated in US cars.
However the code is there, and just needs to be turned on and dialed-in.
I don't recall what masks have it, but it's in the $8D code for sure. Read
about it over on the TGO DIY board. It's meant to improve trip mileage
safely - from the engine's perspective.
As for the rest, GM's stock program was built to make the best EPA mileage/
drivability they could in production car form. Unless you're smarter about
the engine than GM, you should take internet 'tuning' ideas with a grain
(or more) of salt. It's easy to damage the eng, trans, or cats with
haphazard program changes.
JMHO
ECM program. It was not EPA-approved, so it was not activated in US cars.
However the code is there, and just needs to be turned on and dialed-in.
I don't recall what masks have it, but it's in the $8D code for sure. Read
about it over on the TGO DIY board. It's meant to improve trip mileage
safely - from the engine's perspective.
As for the rest, GM's stock program was built to make the best EPA mileage/
drivability they could in production car form. Unless you're smarter about
the engine than GM, you should take internet 'tuning' ideas with a grain
(or more) of salt. It's easy to damage the eng, trans, or cats with
haphazard program changes.
JMHO
Last edited by kaiser; Aug 12, 2008 at 05:10 PM.
Burning Brakes
Joined: Apr 2004
Posts: 762
Likes: 2
From: Huntington ma
The "lean cruise" thing is called Highway Mode. All sorts of urban legends about why it's there, and why it isn't used. I'm sure that I don't know the whole story...
It's in the 1985 $1F, also, BTW...
I Have tried messing with it in My car. I've set the threshold parameters so that it should activate, and I Think I can see it happen in the datalogging (I can't see the timing advance being commanded, which is the Main thing that highway mode changes..). I did NOT see any measurable gain in fuel mileage. That doesn't mean there isn't something to be "found" there, however...
It's in the 1985 $1F, also, BTW...
I Have tried messing with it in My car. I've set the threshold parameters so that it should activate, and I Think I can see it happen in the datalogging (I can't see the timing advance being commanded, which is the Main thing that highway mode changes..). I did NOT see any measurable gain in fuel mileage. That doesn't mean there isn't something to be "found" there, however...
Racer
Joined: Dec 2006
Posts: 292
Likes: 0
I wonder if any models were shipped out of the country that had "lean cruise" enabled. I would be especially interested in the 1989 prom code.
Pro
Joined: Dec 2002
Posts: 522
Likes: 3
From: Rolling Meadows IL
With the 32b bin you could run it open loop by setting the open loop temp to 300 then set the open loop AFR to lean it out. I wouldn't do it.
Another way is with the Zeitronic wide band O2 meter you can change the switch point of the narrow band output from 14.7 to something leaner.
You may want to look at the Smart Car if you want better gas milage.
Another way is with the Zeitronic wide band O2 meter you can change the switch point of the narrow band output from 14.7 to something leaner.
You may want to look at the Smart Car if you want better gas milage.
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Intermediate
Joined: Aug 2004
Posts: 42
Likes: 0
And,
Like the infamous quote from (Barack Obama),
(Air up your tires), Like 60 0r possibly 70#s.
Just think, if we all did this, people like the Kennedy's
wouldn't have to look out over the ocean with their telescopes
and see those wind turbines and oil platforms.
Uh Oh, my bad, wrong forum.
Although this is a milage thread,Rite?
Later
Last edited by jaykar; Aug 31, 2008 at 05:33 PM.
