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fastdude007 07-10-2013 10:50 PM

Gas consumption
Okay here is an interesting issue. My friend has the identical Jeep Grand Cherokee Laredo X with the 3.6l. Mine is a 2012 and his is a 2011. Now, my gas mileage is around 24 mpg highway and about 21 in the city. He drives only on the highway and always does the speed limit using cruise control. His average on the highway is 18 mpg highway driving. The dealer told him nothing is wrong with his jeep. I do need to mention that I drive much more aggressive and still I'm way better with my gas mileage. Any suggestions on why his vehicle is so lousy with gas consumption? His mileage is 40000 miles, mine has about 25000 miles. Thank you for any suggestions....

fin1211 07-10-2013 10:56 PM

Compare tires/tire pressure. Huge factor in fuel consumption.

Mcdenny 07-11-2013 07:47 AM

Re: Gas consumption
He's not using E85 is he?

padgett 07-11-2013 07:58 AM

Re: Gas consumption
Well first check the obvious: tire pressure, alignment, dragging brakes, clean air filters. Has it always gotten bad mpg or is this recent ?

Then you wil need a scanner (PC or Tablet based is under $50 and permits logging/comparison) and this is the boring part: need to make a number of passes with each car while monitoring the paameters.

At the same speed in cruise on a long flat stretch look at throttle position, fuel trim (short and long term), ignition advance, injector pulse width, manifold vaccuum (IMAP), IAT, coolant temp and if any trouble codes are set as a start

Something is going to be different. The most common is a partly clogged O2 sensor that has not failed but is making the engine run rich (short and long term trims).

Anything that can make a 33% difference (18 vs 24) is going to be pretty obvious.

Trouble is that the takes time by someone who is skilled at reading the information. The dealer maynot have anyone like that. However with two vehicles you do not need to understand the values, you just need to look for differences and post here.

As mentioned if you have a Android phone, tablet, or a PC the cost is under $50 for everything from Amazon, can be moved between cars, & most apps can e-mail the results (for iPad or Mac it costs more).

For more than you ever wanted to know see here.

fastdude007 07-11-2013 09:31 AM

Re: Gas consumption
Thank you for your info, I do have the scan tool but not sure how to read it. My friend used to have a gas mileage of 24-25 mpg, but not in the past year, his consumption kept increasing. We both have cold air intakes and the magnaflow catback. You have a good point with the air sensor we will check it out first.

padgett 07-11-2013 08:57 PM

Re: Gas consumption
Have the CAIs made any difference in IAT ?

fastdude007 10-07-2013 03:04 AM


Originally Posted by padgett (Post 856840)
Have the CAIs made any difference in IAT ?

No, it seems about the same. To be honest, I don't think the CAI do anything to enhance performance. The only difference with all the mods is the Diablo Trinity. I actually have a 30 fp of torque increase at the wheels at 1700 rpm with 87 octane fuel and still maintain my 23 mpg in the city. However, the hp numbers decreased slightly.

mswlogo 10-07-2013 01:08 PM

Re: Gas consumption

Originally Posted by fin1211 (Post 856269)
Compare tires/tire pressure. Huge factor in fuel consumption.

That would be my first guess.

Also try swapping drivers :)

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