MPG...Confusion

Smokedawg · 03-20-2001, 01:47 PM

Back when I purchased my 5.0 I was getting decent gas milage. Indianapolis is one way approx 35 to 40 miles.. I could make roughly 3 trips there and back on a tank of gas. Well after about 5 months something just went bad. I have no idea what could have caused this but for some reason my gas milage started dropping significantly. Now it would only get one trip there and back and had to fill up as soon as I got back to town. So thats like only about 90 miles on a full tank. Now after my mods I dont drive it enough to have to fill it up very often but I was just curious if anyone else has had that problem and what causes it.

------------------
347 Stroker Motor: Balanced, 30lb Bosch Injectors, Cobra Computer, Cobra Transmission, Extude Ported and Polished Upper and Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, NGK Plugs, Ram Air, K&N Filter, 79mm Mass Air Unit, FlowMaster Exhaust w/offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Calipers and Drums.

Unit 5302 · 03-20-2001, 03:29 PM

Have you done Rebel79's off road H-pipe fix?

Sounds to me like you are running really rich, probably because of faulty O2 sensors. Could also be a temp sensor.

With a cam, heads, and a stroker like that your fuel economy is going to drop big time, but it shouldn't be anywhere near that bad.

Smokedawg · 03-20-2001, 03:57 PM

Unit,

This drop in gas was before all my motor mods...i have just finished my mods very recently and havent really driven it much to tell how the gas mileage is now..Will making it run really rich make it like your loosing power..cause I noticed that at the same time..

------------------
347 Stroker Motor: Balanced, 30lb Bosch Injectors, Cobra Computer, Cobra Transmission, Extude Ported and Polished Upper and Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, NGK Plugs, Ram Air, K&N Filter, 79mm Mass Air Unit, FlowMaster Exhaust w/offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Calipers and Drums.

Unit 5302 · 03-20-2001, 11:26 PM

Anytime you have a car out of tune you are going to lose power, but neither of those components should hurt wide open running.

They are ignored during floored open loop cycling.

The TPS may be faulty, which could cause a loss of performance, if it's not reading all the way to wide open, and it's messed up in the low range causing extra gas to be dumped in when it's not needed.

I would also suspect the MAF, and the actual computer in this case too.

03-20-2001, 01:47 PM	#1
Smokedawg Tires Fear Me... Join Date: Jan 2001 Posts: 867	MPG...Confusion Back when I purchased my 5.0 I was getting decent gas milage. Indianapolis is one way approx 35 to 40 miles.. I could make roughly 3 trips there and back on a tank of gas. Well after about 5 months something just went bad. I have no idea what could have caused this but for some reason my gas milage started dropping significantly. Now it would only get one trip there and back and had to fill up as soon as I got back to town. So thats like only about 90 miles on a full tank. Now after my mods I dont drive it enough to have to fill it up very often but I was just curious if anyone else has had that problem and what causes it. ------------------ 347 Stroker Motor: Balanced, 30lb Bosch Injectors, Cobra Computer, Cobra Transmission, Extude Ported and Polished Upper and Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, NGK Plugs, Ram Air, K&N Filter, 79mm Mass Air Unit, FlowMaster Exhaust w/offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Calipers and Drums.

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03-20-2001, 03:29 PM	#2
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Have you done Rebel79's off road H-pipe fix? Sounds to me like you are running really rich, probably because of faulty O2 sensors. Could also be a temp sensor. With a cam, heads, and a stroker like that your fuel economy is going to drop big time, but it shouldn't be anywhere near that bad.

03-20-2001, 03:57 PM	#3
Smokedawg Tires Fear Me... Join Date: Jan 2001 Posts: 867	Unit, This drop in gas was before all my motor mods...i have just finished my mods very recently and havent really driven it much to tell how the gas mileage is now..Will making it run really rich make it like your loosing power..cause I noticed that at the same time.. ------------------ 347 Stroker Motor: Balanced, 30lb Bosch Injectors, Cobra Computer, Cobra Transmission, Extude Ported and Polished Upper and Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, NGK Plugs, Ram Air, K&N Filter, 79mm Mass Air Unit, FlowMaster Exhaust w/offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Calipers and Drums.

03-20-2001, 11:26 PM	#4
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Anytime you have a car out of tune you are going to lose power, but neither of those components should hurt wide open running. They are ignored during floored open loop cycling. The TPS may be faulty, which could cause a loss of performance, if it's not reading all the way to wide open, and it's messed up in the low range causing extra gas to be dumped in when it's not needed. I would also suspect the MAF, and the actual computer in this case too.