I just got Tuner cat and have been playing with it (putting a LT1 in my 91 Camaro) and I was wondering if anyone ever made one for getting good gas milage. I figure I would have 3 bins made for myself, one for track, one for daily user to and from work and one for gas milage on those out of town trips. Anyone ever done the gas milage one? I would really love to know what to look for on this. Thanks.

 

oh its a 95 OBD I from a trans am with a T-56 (which I also have ).

 

Cool thanks, any input from anyone else?

 

im kinda new at this, but i got to ask, how would increasing anything in open loop help him on a long trip? Not flaming, or thread jacking, just learning. Thanks, prorac1

 

This is my second time through pcm programming. I was doing all this 2 years ago. I have to relearn or remember everything.

I think now I did get my understanding of Open Loop backwards. Closed Loop is when the pcm is going off the 02 sensors so any adjustment in Open Loop will not matter once the system is warmed up. Sorry about the missinformation. I'll delete my earlier reply so as to not screw anyone up.


Hal

 

Well, you could lean it out alot.

Also this next one will take some trial and error. Find the spark advance values that produce the most manifold vacuum. At cruising speed and rpm that is. Your car should be most efficient at that time.

 

The only thing you could possibly do is the eliminate PE mode. That way the car never adds fuel for WOT operation. Would I suggest you do this? NO!

Another thing to do is to go into permanent open loop. However, since the computer is not reading the crosscounts of the O2's, there is now way for it to know for sure what it is giving for fuel is correct. Your MAF better be dead-on in this situation.

Ben

 

Wouldn't altering the Volumetric Efficiency tables help? I notice the HPP+powerpak.lt1 file uses the VE tables extensively. I would think that would cause it to lower the amount of fuel to depict a more efficient air to fuel burn.

Hal

 

I really don't think you want to base anything that you're going to do off of what you find in a hypertech.
Besides, you can alter injector constants and ve tables and maf tables all you want, but under closed loop part throttle conditions the computer is going to use feedback from the O2 sensors in order to adjust fueling on its own. You really don't have much control other than that.

 

I am not sure that altering VE tables works. I used VE Master to fix my tables to get to a blm I like and it did nothing. I did this several times with no change to blms. Maybe it only works on S/D cars.

You can change the A/F ratio the O2 sensors shoot for and that should make a difference in gas mileage.

Also, changing injector constants MAY help with gas mileage. Mine were 108 with no tuning. Which meant it was dumping way too much fuel at WOT. I got them closer to 128 using the inj. constant so less was used.

 

Well thanks for the info guys, I really don't know what im doing yet and havn't even gotten into doing this but am reading and checking tuner cat on everything you guys are saying, I really appreciate the help and I believe if I can get this to work it will save me at least a little on those long trips, thanks guys.

 

How do you do that?

 

slimdawson, changing the injector constant probably just moves the injectors to the 128 cell. It does not actually alter the AF, it just increased how long the injectors were open (pulse width) which caused the same amount of gas to dump before each cylinder fired. But, that probably helped because maybe you were actually a bit lean (could go no lower than 108). Also, you can only change Open Loop AF. This is only useful at WOT or when the engine is cold and in OL.

The oxygenated additives manufactures use is worthless in a 02 sensor car. All oxygenated additives do in our engines is REDUCE gas mileage and increase the cost of the gas. Only about 40% of gasoline is actually gas, the rest is additives (look it up!). That's why when the price of a barrel of oil doubles, gas does not double, it only goes up about 40%. If we had pure gas (or at least gas without the unnecessary additives) we would be getting a lot better gas mileage because it would be pure gas and the engine would not need as much of it to produce the same work. Heck, those idiots required a very environmental hazardous additive (MTBE) be used! If you think they overlooked the known risks for your good, then think again.

 

I thought with the tuner cat that you could disable the o2 sensors?

 

the only way to tune for better gas mileage is to adjust the timing for a more efficient combustion. Adjusting the timing is very easy and simple to do.. knowing whether to advance or retard is the tricky part.