Gas mileage getting reeeeeeal bad

[BRZ71]

Over the past week or two I have noticed my mileage dropping. I am getting about 30 to 40 per qtr tank. No MIL light. I have also noticed a slight power drop, but not all the time. Some days it runs like hell, some it feels like a dog. Any suggestions?????

[ChevyTech007]

You might want to pull the vacuum hose off the fuel pressure regulator and check for any gas. If there is any sign of gas, replace it.

[Mark_in_Tulsa]

You might want to pull the vacuum hose off the fuel pressure regulator and check for any gas. If there is any sign of gas, replace it.

 

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Yeah what he said.

Next I would go with checking the cat, and the O2 sensors.

[BRZ71]

I have checked the Regulator and see no fuel it the line.

 

I have a Diag program for my laptop. The question is, what should the voltage from the O2 sensors be if they are functioning properly?

 

Also I have cleanded the MAF sensor with electronics cleaner, should my idle etc. change when it is unplugged??? I unplugged it to see and there was no change. I had the reset the MIL light with the program after though.

[asepgrad98]

could somebody be steal gas at night?

[Rammer]

I have checked the Regulator and see no fuel it the line.

 

I have a Diag program for my laptop. The question is, what should the voltage from the O2 sensors be if they are functioning properly?

 

Also I have  cleanded the MAF sensor with electronics cleaner, should my idle etc. change when it is unplugged???  I unplugged it to see and there was no change.  I had the reset the MIL light with the program after though.

 

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The PCM will revert to Speed Density mode with the MAF unplugged and it will run and idle good. The O2 sensors should oscillate(rich-lean) quite a bit. They don't stay at a constant voltage.

[VANZ71]

Over the past week or two I have noticed my mileage dropping.  I am getting about 30 to 40 per qtr tank.  No MIL light.  I have also noticed a slight power drop, but not all the time.  Some days it runs like hell, some it feels like a dog. Any suggestions?????

 

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Is your water temp getting up to full temp or staying in the low range ? Maybe somebody is stealing your gas/playing a trick on you, maybe they will put it back next week and you mileage will go to 22..

[sonjaab]

Is your truck stock?????????

[BRZ71]

Truck is stock. I don't think anyone is take gas out of the truck. I am going to hook it up at some point this week and see what the O2 sensors are reading.

[VANZ71]

Truck is stock.  I don't think anyone is take gas out of the truck.  I am going to hook it up at some point this week and see what the O2 sensors are reading.

 

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Had almost same probelm with brand "F"...thermostat was stuck open and water temp never got above 160F so ECM never went into closed loop.

[BRZ71]

I don't think it is the t stat, I run at 210 steady once warmed up.

[BRZ71]

Here is what my Diag software got me

 

O2 Sensor Bank 1 Sensor 1 .100 v to .760 v up and down

O2 Sensor Bank 1 Sensor 2 .690 v to .700 v up and down

 

O2 Sensor Bank 2 Sensor 1 .075 v to .805 v upa and down

O2 Sensor Bank 2 Sensor 2 .160 v to .805 v up and down

 

MAP Sensor 42 Kpa

 

MAF Sensor 6 g/s

 

Coolant Temp 92 Celcius

 

Intake Temp 69 Celcius

 

Spark Advance vaires from 16 to 20 degrees

 

Absolute Throttle position between 6 and 7 percent

 

Longterm Fuel Trim 1 -3%

Longterm Fuel Trim 2 -2%

 

Do these look within specs????