I have an 89 formula 350 firebird. When i got it, I would get around 120 miles before my next fill up. Then when i cracked my valves we machined the heads and i got alittle more. Then I put high flow cats, a flowmaster, filter charger and accel plugs/wires/&supercoil. I now have around 140-150 to the tank. But what is up with the bad gas mileage?? It seems like the more power I get the better the gas mileage gets but it just slowely grows.

 

Is there anything majorly done to the engine?? Like radical cam?
If not, have you done the basic tune up EVERYTHING? Maybe an 02 sensor problem?
You need to make sure that everything is in proper working order.
This post needs to be moved to the general tech board, which i'm sure one of the moderators will do shortly ;P


Hope that helps.

Brendan

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1987 IROC-Z L98,SuperRam,EB 6085's,LPE 219/219 Roller, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, MSD 6AL, MSD Blaster 3, Aluminum DS, 94 Disk Rear, Adjustable Valve, Precision 3.73 Gears, Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

To see the ROC, Check out the webpage Here

 

You can't drive with your gas pedal floored all the time. On a more serious note, if you have a lower-temp thermostat, the highway fuel mode isn't being activated, which is enabled at 185 degrees coolant and 55 mph. This probably could give you 1-3 mpg depending on how many miles you spend on the highway vs. around-town driving...

Edit: Cool, 300 posts!

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Greg Westphal
'87 IROC 305TPI/A4

[This message has been edited by GregWestphal (edited March 23, 2001).]

 

Hey Greg,
I've seen that you can change the speed in which "Highway mode kicks in"; but can you change the temp to a lower one?

Something else, I'm using WinBin for now and under flags for "Vats and Tranny" there are a bunch of b1, b2, b3-b7.....what are all these? I was looking for something like disable EGR, but it aint there. Same for flaghs under "AC Pressure switch bytes"
How about "Minimum MPH for ESC Enable"; what does this mean?

I'm sorry for all the questions, but I'm brand spanking new to this.
Thanks a LOT, Rick

 

I cannot say for sure on an 89 MAF, but so far, all BINs I've looked at has had the Highway Mode disabled because the MPH enable speed is set to 255 mph. GM purposely disabled it and it must be enabled.

As for your general poor mileage, I found a cooler t-stat caused the engine to think it was perpetually in "start up" mode and ran excessively rich.

 

On SD cars, yes, the minimum coolant temperature for Highway Mode can be adjusted. Also, with SD cars, there is a maximum MAP reading to kick it out when you are under a load condition. Not sure how this is handled with the 6E eprom.

 

I would have to agree with Glenn and the others about the 160 degree Thermostat. I just pulled the one out of my car that the previous owner put in. Just put a 180 in and it runs much better. I would highly suggest the same.

Brendan

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1987 IROC-Z L98,SuperRam,EB 6085's,LPE 219/219 Roller, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, MSD 6AL, MSD Blaster 3, Aluminum DS, 94 Disk Rear, Adjustable Valve, Precision 3.73 Gears, Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

To see the ROC, Check out the webpage Here

 

Yes, you can lower the enable temp, and it should be in the next ecu for WinBin. Those flags are in the BUA hack, but only several are defined. They're just switches for things like type of A/C switch, manual/auto tranny, single fire/double fire mode, VATS, power steering switch, etc.

One way you could disable the EGR is go to the EGR Duty Cycle table (or whatever it's called) and set all of the values to 0%. There are %TPS enable values too, but I don't remember if they're in the WinBin ECU yet. Minimum MPH for ESC enable is the vehicle speed at which the computer uses the knock sensor input. I have mine set at 10 mph to get rid of false knock when launching at the drag strip, but that's also the stock value from my car's original PROM (ABUN).

Highway fuel mode was definitely activated in the MAF cars since the speed and coolant temp enable values were pretty reasonable. As far as the maximum load that highway fuel mode is active, the stock setting is an LV8 of 125 for 305's and 140 for 350's from what I've seen.

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Greg Westphal
'87 IROC 305TPI/A4

 

Greg, I desperately need this BUA Hack. There is a bunch of stuff that I have no idea what they mean. Where can I find this info?
Thanks, Rick

 

Go to:

http://www.geocities.com/MotorCity/S...g/do_tune.html

and click on the $32 Example Hack listed on the left side of the screen. It's a .pdf file, so you'll need Adobe Acrobat Reader or something like that. Enjoy, cause it's a long file with almost 300 pages, of which less than 1/3 is the actual data and stuff, the rest is the instructions and such.

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Greg Westphal
'87 IROC 305TPI/A4

 

True enough; however, the BUA hack has highway mode spark disabled below 6350 RPM. Oddly enough, I didn't see any reference to highway fuel mode. The hack is from an '86 Corvette. Also, the max load value for highway mode is only 100, though I've heard that the programming in Corvettes, in general, uses lower LV8 values than in F-bodies.

 

My AXXD chip had the highway mode enabled at 50 MPH, but the AFR was set to 14.8, not noticeable. I set it to 15.7 and gained 1 MPG so far, but I havent verified the setting with Diacom yet. I am running a 160º thermostat.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

what exectly do u mean??
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what exactly do u mean??? and what do u mean about the maxium load?

 

Oldie, but, I feel like typing...

The MAF cars calculate a load and call it LV8 "load value 8 bit".
He means that in some MAF cars, highway mode was enabled at normal temps, and it is used at light to medium loads, less than that "maximum" value. Highway mode is a lean cruise mode, where it requires some time at a stable load condition, and makes a leaner AFR and adds some spark timing.

This was "outlawed" because it "defeats an emissions control device". It makes higher NOx emissions, but yeilds better fuel economy.

Most XDF or ECU definitions have those byte locations defined, so you can easily enable it, and nobody will know you did it. It's common to make the AFR 15.5:1 and add 3 degrees of timing, or so. Enable it at about 180F or so. There is also some delay times to "optimize" for it. A few seconds should be done in closed loop so that the BLM is correct, so that the actual matches the commanded AFR. There are some speed thresholds to enable it too.

I think all the GM TPI stuff - at least $6E and $8D - had this for sure.

Might as well do it. Emissions are only for cities. MPG is for customers and fleets, and the rest of the world.

P.S. I would USE EGR, as long as the valve is properly functioning. It allows more open throttle, and less NOx, and!!! I am researching still, but!!! I think the H20 acts somewhat as a catalyst in the CO-CO2 conversion which is a major portion of the later part of the combustion. Which defies the common thinking of EGR as "inert". The net effect when using via EGR - I don't yet know.

 

ok so how do i enable this?

 

i have 185 degree one in is that ok??
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what is winbin?