89 MPG per tank

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ChristianKustom

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Aug 5, 2010
Hey all. I gots a nother problem and this one is freaking me out. At $4.19 per gallon I need help with this ASAP. I filled up this morning to a full tank. I drove 89 miles and I was near empty. Car is faster then it was at the buick national event in NC but wow...89 MPG's. My wideband reads 13.2 at idle and 14.6 @ cruising speed of 55mph+. O2 is reading 710-744 at idle but fluctuates from 23-800. it varies depending on if I am decellerating (when it drops to it's lowest). I have another O2 sensor coming from Brian at GBody but besides that I am at an absolute loss. Every sensor I have is new and TPS is set at .44 volts. Erics ALKY chip will be in here in the next day or two. However nothing has really changed since the drive back except for the fact I am running ALKY now...by the way LOVE IT! 26 PSI really moves the car. If I can get it to stop buring so damn rich she'll be even faster. But I don't know what else to do. This has me stumped. There is not too much tweeking I know how to do with this car so any help would be great. Thanks.
 
No. you had it right the first time...89 miles per tank full of gas. I would have not believed it myself if I did not see it for myself. I still did not believe it until I went to the fueling station and put in another $50+ dollars. EEEEK!
 
yes. 89 miles per tank of fuel. I have the car at my shop right now till I figure out what is going on. I do not want to risk hurting the car. especially with it drinking fuel like that. I have never seen anything like that before...even on fully blown race engines. This is crazy. Any idea's?
 
are you sure?

Are you sure your odometer is accurate? or maybe your guage is off-did you top it back off?
 
Yeah...checked that already. Everything is dry. No leaks. everything is new in the tank. New sending unit, new TurboTweek Walbro340 pump with in tank upgrade and the hot wire kit. Fuel rail is solid with no leaks and I have a new set of Precision 60lbs. injectors from TurboTweek. (Thanks a load Eric. Parts are awesome and shipping was fast A+++).
 
yes. It is a new sending unit. Plus when I went back to the fueling station I put in another $50+ in fuel. I think it was around 10+ gallons. So I am sure it's burning that much. I have never seen anything like this before.
 
gas

I would pull the dip stick and make sure its not going in the crank case.then I would pull the plugs it's hard to believe that you could put that much fuel through it and it not foul the plugs out.I would rather believe it's leaking somewhere I had a fuel return line have a hole rubbed in it and was squirting fuel on the headers so it wasn't leaking all over the ground was getting bad mileage but not near that bad.was lucky it didn't burn up.
 
10 gallons doesn't fill a GN gas tank, I'd totally top it off and drive it around with the wideband installed.

To be clear, you just installed new 60lb injectors but didn't install the chip for them? Is the chip in the GN during this time period for 60lb injectors?

Redo the fresh air calibration on your Wideband and install the new chip, there's something not making sense here.

Post up as much Scanmaster data as possible.
 
I am running the 60lbs Precision injectors with the TurboTweek chip. Eric is sending me one now that I am running meth. He said the only difference in the chips I need is just a tad bit more timing advancement. I am running 26psi on 5.5 ALKY.

WB reads 14.6 at cruising speed, ave. 13.2 @ idle and WOT is inconsistant. Reads 12.2-10+. I have checked the FP and reads 43psi off vac. &38 on vac. No fuel drop off under WOT. 1psi per 1psi of boost correct? 38psi + 26psi boost = 64psi fuel pressure.

Scanmaster reads 0.0 knock now that I found my correct ALKY setting. O2 reads all over the place. Brian from GBody is sending me a new one. it will read (when warm) 714 to 800 but fluctuates down to 23 at times and climes back up. It's not really consistant. TPS is steady at .44 volts and 4.51 @ WOT. I will try and get the rest of the #'s tomorrow and post em. Those are just the ones I remember off the top of my head. I also remember the one before BL was 128 and my BL was 118. A/F was bouncy but was usually low and 255 @ WOT.

Not sure what you mean by fresh air calibrate my wideband. It's a simple plug and play. I do have a reset button on the modulator box if thats what you are talking about.
 
Ok, you filled up, completely?, and drove 89 miles, you were "near empty" and put $50 in your tank. That's only around 12 gallons of fuel, the tank holds 18 gallons I think.

Fill the tank completely, drive it 100 miles (the math is easier) and refill the tank. That will tell you what mileage you are getting. Also, if you did a lot of full throttle "runs", that will negatively effect your mileage. My old '71 Camaro got 5-6mpg with a 4.56 gears and a heavy foot !!!
 
If you went into boost a few time that could explain where the fuel went. Pump gas and Alky owners tend to "have fun".
 
Alcohol has nothing to do with gas mileage.

Your foot mashing the gas pedal does.

You will get poor mileage hammering on the car. Period.

Fill tank.. drive car for 30 miles without going into boost.. refill. Divide miles driven by gallons put in.. there your MPG. Miles per gallon.

If you cant drive 30 miles without getting into it.. then there you have the problem :D You want gas to last but at the same time you want to have the thrill of 26 PSI boost. Racing the engine and getting gas mileage.. aint going to happen.

I think 89 miles is pretty good IF your beating on it. :D
 
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