2004 Grand Cherokee 4.7L V8 - Improving Fuel Efficiency?
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2004 Grand Cherokee 4.7L V8 - Improving Fuel Efficiency?
Given that it’s now 2018, I wanted to ask a question that’s been asked a handful of times before, albeit back in the early 2000s. I just picked up a used 2004 Jeep Grand Cherokee with 83,000 miles on it. I decided to bite on it because, with the exception of undercarriage rust, the single owner took incredibly good care of it. It was hard to find a 2nd or 3rd gen Grand Cherokee in my area with only 83K miles, and even harder to find one that looked brand new.
The thing that doesn’t excite me is fuel efficiency. Of course, I wouldn’t have bought it if I wasn’t ok with averaging 16 mpg. However, I figured it’d be worth asking some Jeep owners the following:
Other than changing my driving habits and conducting regular maintenance/tune-ups, how can I improve the fuel efficiency of this vehicle? It’s been 14 years since the vehicle was released, so are there some new aftermarket parts that are good for improving fuel economy?
These are the recommendations I’ve found so far by looking at old threads:
The thing that doesn’t excite me is fuel efficiency. Of course, I wouldn’t have bought it if I wasn’t ok with averaging 16 mpg. However, I figured it’d be worth asking some Jeep owners the following:
Other than changing my driving habits and conducting regular maintenance/tune-ups, how can I improve the fuel efficiency of this vehicle? It’s been 14 years since the vehicle was released, so are there some new aftermarket parts that are good for improving fuel economy?
These are the recommendations I’ve found so far by looking at old threads:
- K&N Intake
- Fuel Injectors
- Superchips Programmer
- Exhaust
Last edited by PerryGriffith; 08-05-2018 at 06:44 PM.
#2
Old fart with a wrench
Ah....no. Other than a high flow muffler, there isn't much that will improve the mileage because remember, you're still turning 2 axles worth of gears and about 2 tons of metal. I've heard weird stuff like locking out O/D so the engine runs at a higher rpm with less of a load, but I doubt that will help. I'd stick with the stock intake and filter system because it's already pulling in high pressure cool air from in front of the radiator.
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Avoid K and N . High flow catalytic converters and high flow mufflers will definitely help . Tire size , the fuel and ignition system being in top condition , a good clean air filter certainly helps. I think for the most part good maintenance is key but like Dave said exhaust is the biggest impact .
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Avoid K and N . High flow catalytic converters and high flow mufflers will definitely help . Tire size, the fuel and ignition system being in top condition , a good clean air filter certainly helps. I think for the most part good maintenance is key but like Dave said exhaust is the biggest impact .
#6
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I don’t want to say a figure because I don’t want to mislead you and I don’t have a definitive answer . However a lot of factory exhaust systems are quite restrictive and a good quality exhaust system could PROBABLY Net you a couple miles per gallon if I had to make a bet .
#7
Old fart with a wrench
The max MPG I got with my 2000 4.0 was on a long high speed run without A/C on a 300 mile flat cruise with very little wind and a 2-way trip. I got 26 mpg and that shocked me! That's the one and only time I got more than about 18. I'd be very careful about high flow converters because the 02 sensors are designed to work with a certain backpressure and the PCM might get confused. Just my opinion, however. Since that trip, I've installed a Flowmaster 50 but haven't checked the long trip mileage yet.
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Year: pair of 99s
Model: Grand Cherokee
Engine: 4.0
Modern exhaust systems are not as restrictive as the old ones. In fact the only way it would really help out is if you are pushing it over 4000 rpm regularly.
All the mods you listed might get you 3-4 more mpg, yet cost you a few grand to get them all installed. That's a bad return.
I'd recommend all synthetic lubricants. Maintain good tire pressure and stick with a stock size with a decent street tread. Install a vacuum gauge and learn how to drive to maintain maximum vacuum. Doing this will get you the same 3-4 mpg increase and will do it for under grand, even if you include all new tires. Skip the tire replacement and you can do it all for a few hundred bucks.
All the mods you listed might get you 3-4 more mpg, yet cost you a few grand to get them all installed. That's a bad return.
I'd recommend all synthetic lubricants. Maintain good tire pressure and stick with a stock size with a decent street tread. Install a vacuum gauge and learn how to drive to maintain maximum vacuum. Doing this will get you the same 3-4 mpg increase and will do it for under grand, even if you include all new tires. Skip the tire replacement and you can do it all for a few hundred bucks.
Last edited by HP2; 08-05-2018 at 09:12 PM.
#9
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Modern exhaust systems are not as restrictive as the old ones. In fact the only way it would really help out is if you are pushing it over 4000 rpm regularly.
All the mods you listed might get you 3-4 more mpg, yet cost you a few grand to get them all installed. That's a bad return.
I'd recommend all synthetic lubricants. Maintain good tire pressure and stick with a stock size with a decent street tread. Install a vacuum gauge and learn how to drive to maintain maximum vacuum. Doing this will get you the same 3-4 mpg increase and will do it for under grand, even if you include all new tires. Skip the tire replacement and you can do it all for a few hundred bucks.
All the mods you listed might get you 3-4 more mpg, yet cost you a few grand to get them all installed. That's a bad return.
I'd recommend all synthetic lubricants. Maintain good tire pressure and stick with a stock size with a decent street tread. Install a vacuum gauge and learn how to drive to maintain maximum vacuum. Doing this will get you the same 3-4 mpg increase and will do it for under grand, even if you include all new tires. Skip the tire replacement and you can do it all for a few hundred bucks.
#10
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The max MPG I got with my 2000 4.0 was on a long high speed run without A/C on a 300 mile flat cruise with very little wind and a 2-way trip. I got 26 mpg and that shocked me! That's the one and only time I got more than about 18. I'd be very careful about high flow converters because the 02 sensors are designed to work with a certain backpressure and the PCM might get confused. Just my opinion, however. Since that trip, I've installed a Flowmaster 50 but haven't checked the long trip mileage yet.
#11
Old fart with a wrench
Oh, I'm not saying a new clean converter won't help, because I ran Mr Gasket "Cataclean" thru my WJ and the difference was amazing! I'm just saying that aftermarket high-pass converters might give the emission system headaches.
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