Brangeta

Is there any way to tune the car or modify the car to where you can either manually switch displacement on demand/active fuel management ON or have it come on more often/sooner? Gas is expensive and I really don't see why I need to be in V8 mode when I'm driving stoplight to stoplight or stop sign to stop sign in 30 mph areas.

Battle_Ravage

It can be tuned to come on earlier and apparently there is a way to install a switch, dunno how though.

TiredGXP

iTrader: (2)

You can change the tune to enable DoD in lower gears, but there's no point. Engine load under acceleration is too high for DoD to enable with the stock settings - you could tune for that, but it would really screw up how DoD operates at highway speeds. It is not possible to tune it for individual gears; enable/disable parameters are global settings.

Want better gas mileage? Ditch the V8 and buy a four banger.

Brangeta

What are the parameters for DOD to kick in? Anybody know when it kicks in with some technical data at all?

I'm possibly/probably ignorant, but I'm thinking that if DOD kicks in at say... 10% throttle in gears 3 and 4, then perhaps it could be changed to kick in at say... 20% throttle in all gears.

Any input from people who have done tuning would be cool, because I've never done it or had it done.

KurtMCSS

Dude your lucky to even have DOD. Sell it for a 92 accord or drive slow as ****.

06MonteSS

heh, no, it doesn't work like that...

there are a whole lot of parameters that need to be met in order for DOD to activate... rpms, throttle position, vacuum pressures, engine load, etc etc...

you can find all DOD info here in the Word docs:

http://gmls4.com/index.php?topic=9.0



.

Brangeta

Because everything is stop and go in my area, I average 14.8 with the A/C turned off and 12.8 with the A/C turned on, and that's with driving in manual mode (otherwise 12.4 with A/C on in Drive). It'd really help I think just to be able to average 15 or 16 without having to turn the A/C off.

Air filter's clean... tires are properly inflated... carrying less than 15 pounds of junk with me... and rotten mileage just because there are so many stop signs and stop lights in my area. Being able to be in 4-cylinder mode more often would really help.

I've even determined the best way to get good mileage in my GXP is to accelerate to 30 in 1st, shift into 2nd and immediately into 3rd when not in traffic. If the speed limit is 35 and I'm on a short drive, I'll put it in 4th. Can't do that on a long drive because it heats the transmission fluid up after about 30 minutes of driving.

EmersonHart13

iTrader: (3)

This is not a good car for MPGs with regards to stop and go. You need to walk, ride your bike, public transportation, or get a scooter because it sounds like you have done just about everything you can to "improve" mpgs with the LS4 in city driving.

Battle_Ravage

Pick up a beater for a few hundred bucks.

ls4door

When I am home I primarily have your driving situation. It sucks man however a friend of mine is a hypermiler to the hyperest. I do a procedure called pulse and glide. I take off 2nd gear at 20 3rd gear at 30 and if I get up to 45 4th. What I do is say speed limit is 30. accelerate to about 35 mph gently let it coast down to about 28 ish. while doing this watch your instant and you will notice it goes up really high when you are coasting. My friend uses this method with a bunch of other tricks we don't have (electric motors and manual control of them 5 speed and like a 5 hp brigs haha) anyways he can easily rip of 100 mpg runs to and from work, when the weather is warm. That is another factor I have noticed I just came back to indy and got 27.2 for the trip. A month ago i got about 23. I did go a little easier on it but still drove pretty close to the same.

Brangeta

I thought about doing that ('96 to '97 V6 Camaro), but I think the cost of insuring it would offset the amount of money I save on gas.

I love the GXP too much to get rid of it.

Didn't GM have a concept car a few years back with an electric motor in each wheel? How about two of those for the rear wheels?

That's kind of an interesting idea. I use the cruise control once I stick it in 4th so I don't have to manually feather the gas when going just over 30 mph in 4th, which helps a lot, but getting up there is rare.

I only use 2nd gear when I am...
...behind somebody in traffic and I can't quickly accelerate in 1st up to 30
...don't need to go all the way to 30 or 3rd gear because the next stop sign or light is too close

If you want to try hypermiling your car a bit more, take my advice and basically skip 2nd gear for accelerating. For getting on the highway, to be the most fuel efficient (that I've been able to get) is accelerating up to 40 in 1st, shift to 2nd, and get up to the speed limit in 2nd, then shift quickly to 3rd then 4th.

The gear ratios in these cars are not particularly good. 1st is good, it tops out at about 50, but 2nd tops out around 90+ so unless you're going faster than about 35 or 40, it's not all that useful for accelerating. And then 3rd is fine at around 1:1, but 4th is bad because it isn't low enough. You really shouldn't be able to get into your highest gear at 20 miles per hour IMO. I wish 2nd topped at 70mph and that 4th was lower or we had a 5th.

ls4door

Or have the High Cat Temp removed?!?

babbage1109

iTrader: (11)

I never realized those cars got poor gas mileage.

Brangeta

Can you explain that? I'm not sure what you're talking about.

Also, I have another question. Does engine braking (downshifting to slow down) consume more fuel than simply staying in gear and using the brakes?

ls4door

I have read about the high cat temp it is a emissions thing. I think DIABLEW does something with it. Several people have it done I believe.

As for the engine braking if you are letting it rev a lot higher then it could but how much is prolly small. I do all the time just so I can hear the exhaust!! Also keeps me from squeaking my breaks in traffic (they are horrible)

RobRomero

iTrader: (1)

Dammit man, it's a muscle car, not a VTech...

vroom_vroom

iTrader: (5)

x2

i hope you guys like replacing the trans putting it on o/d at 35mph!!!!!!!
that kind of crap puts so much stress on the motor and trans that sooner or later **** is gonna get fucked up

not to be a dick but if fuel consumption is THAT big of a problem its time for something else "how fast can you afford to go" is the question

rvd9431

seriously no wonder these trans' get a bad rap people do that **** to them on a daily basis just drive your car minus the lead foot, if its that big of a problem buy a beater

heavyft

As heavy as the car is I think just 4 cylinders would use as much gas or more than V8 mode.

06MonteSS

yep.. that's the COT you're talking about... the Catalytic Over Temp protection... it dumps in extra fuel to cool the Cat down when it gets hot....

BUT - that only gets disabled if someone totally removes their Cat... if you still have a Cat on the car, even a high-flow one, that needs to stay on/active, otherwise you could burn it up...