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I've noticed a somewhat serious erosion of my fuel economy lately in my 1996 Caprice with the LT 1- B4U and 136 K. I use to get about 15 MPG which I considered reasonable but over the last year it has dropped to 12 MPG. I'm a volunteer fireman sometimes I get on her to get to the firehouse, and take an occasional approximately 35-50 mile trip to Jones Beach once or twice a week so I know there is some around the town driving which can be injurious to optimal MPG. But this routine hasn't changed much over the last year,or more so I don't understand why there is an approximately 20% drop in fuel consumption over that period. I checked air filter - that seems OK since I've been very conscientious about taking care of the car mechanically. (I change oil every 2000 since I bought the car new) Love the car,even though the cruise control and defogger have died.
Anybody got any ideas besides the air filter?
Anybody got any experience with the MPG meter like the Ecometer, or Ultragauge EM Plus?
Thanx
HockeyJohn1
 

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My daily commute 20 miles to and from Bethpage each way, always averages 20-20.5 mpg in the 91. And for as long as i can remember, it becomes around 18 in the winter months. For as long as I can remember. Closing in on 20 years. Always thought it was the winter fuel blend. But could also be the combo of the gas, the studded snows, or longer warm up. Might want to see if mileage returns in a few more months.
 

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Hi HJ1, yeah something is off. i have a SS and use fuelly.com to track mileage for years, so you can look up my stats if you want. Since 96, very easy for you to use android phone and free app and bluetooth dongle on OBD2 port to real time watch stuff like MAF, timing, O2's, fuel trim, etc.....
i use Torque and "inCarDoc" cuz it does MPG.
-ALF out....
 

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I've noticed a somewhat serious erosion of my fuel economy lately in my 1996 Caprice with the LT 1- B4U and 136 K. I use to get about 15 MPG which I considered reasonable but over the last year it has dropped to 12 MPG. I'm a volunteer fireman sometimes I get on her to get to the firehouse, and take an occasional approximately 35-50 mile trip to Jones Beach once or twice a week so I know there is some around the town driving which can be injurious to optimal MPG. But this routine hasn't changed much over the last year,or more so I don't understand why there is an approximately 20% drop in fuel consumption over that period. I checked air filter - that seems OK since I've been very conscientious about taking care of the car mechanically. (I change oil every 2000 since I bought the car new) Love the car,even though the cruise control and defogger have died.
Anybody got any ideas besides the air filter?
Anybody got any experience with the MPG meter like the Ecometer, or Ultragauge EM Plus?
Thanx
HockeyJohn1
How many miles on your sparkplugs? Fuel mileage on my 96-B4U dropped off a cliff when they were worn (90k+ miles). It was not subtle at all! New plugs, mileage back up.
 

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Anybody got any experience with the MPG meter like the Ecometer, or Ultragauge EM Plus?
I have not used these specific devices but will comment on how they work. If it plugs into the OBDII port it is getting distance and INJECTOR time information from the car's PCM. In theory this should work. In practice the port was not intended for this purpose and can be slow about delivering the data to the accessory gauge. Depending on how the gauge"s engineers program to compensate for the low data rate you may get low or high results.

I have driven several cars with built in MPG systems and have not found them accurate. If you do not like "paper work" there is nothing wrong with using then as a "bench mark" to see if things are getting better or worse.. But the number displayed may be +- what the car is really doing. The instant readings are great for learning how to increase MPG. Less pedal after a full stop, letting off sooner, or timing things so you roll through green lights instead of doing a stop go at a light I understand this is not what this thread is about.

The best way is what you are probably doing collecting mileage and fuel amounts every fill and averaging the results over many fills. A phone app or spreadsheet is the easy highteck way.

If the MPG drop is not related to the fuel supply(alcohol) you are left with the normal suggestions of spark plugs, spark plug wires,MAF cleaning, clean TB, clean intake, and many others. It is amazing what problems the PCM will hide to keep the engine running.

Doing one less highway trip a week will change your MPG. When I do not "pop" into the big city to shop my MPG goes down due to small town driving.

Make sure a 96 Caprice is supported by the gauges. I have no experience with the 96 OBD!! as I have a OBD1 94. I remember reading that people were disappointed with what the phone apps displayed.
 

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Costs almost nothing to clean your MAF sensor.
Speaking of keeping your throttle body clean, replace your PCV Valve - preferably with 12572717, the Gen4 SBC PCV thingy (instead of the mid-'90s LT1 PCV Valve from 1987).

Does your EGR Valve work properly? If not, ask for a '96 manual LT1 F-car EGR Valve.
 
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