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Why am I getting bad Gas Mileage?

JDCMoney

JDCMoney

New member
Since I got my GTP in November, I had no 4th gear so I figured thats why I'm only getting 19 miles per gallon.

But a month ago I put a used transmission in. All gears work great engine runs cherry, yet still only getting 19 miles per gallon when babying it and I saw 16ish one tank full when I was heavy footing it for a week.

The DIC is saying a constant 19.3 or 19.4 When I calculate it I have been seeing anywhere from 18.7 to 19.1.

Any ideas?
1998 GTP , 185K, Full tuneup not long ago, with Accel 8.8mm wires, AL104s gapped at .055, Mobile 1 oil and filter. No codes. My interceptor isn't reading any misfiring. It reads less than a degree of Knock under WOT.
My mods are in the signature.
 


I have the same question. Best city I get is 18 and best highway is 22. I don't driver hard and I only use 94 octane.
 
Anybody else with the DHP tune having bad gas mileage?

My rear o2 sensor is fairly new and is in a spark plug anti-fouler to raise it up due to the cat delete.
 
corsagtp said:
I don't have an o2 sensor. I got rid of my cat and put a o2 emulator in. Not sure if that makes a difference though
Click to expand...

you have a front o2 sensor. those will lose their "touch" over time and starting causing poor fuel mileage, without illuminating the SES
 


The 19 doesn't sound bad around town, really. Was that in the winter?

If I REALLY baby it, I can stay around 22-23 back and forth to work - about 13 miles. On the highway, I've seen 32 mpg and that was a couple weeks ago and always running premium fuel. I've never driven it in the winter, so I don't know what to expect, but I imagine it will drop off a bit.
 
JDCMoney said:
Anybody else with the DHP tune having bad gas mileage?

My rear o2 sensor is fairly new and is in a spark plug anti-fouler to raise it up due to the cat delete.
Click to expand...
I've got a DHP tune and have pretty crappy gas milage. Going to have a street tune in the near future
 
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