airman Posted January 8, 2006 Posted January 8, 2006 (edited) I have a 1996 Jeep Cherokee 6cyl 4.0L automatic 4WD. since about 6 months ago my gas mileage has been steadily dropping. for the first ~2 years that i had it, it kept around 16-18mpg or so. however over the past 6 months it's dropped down to about 12-14mpg. what could cause this? it wouldn't happen to be my amp/sub that i put into my car about 3 months ago would it? 12w6v2 rockford fosgate 851S amp soooooooooo any suggestions of what it might could be? Edited January 8, 2006 by airman Share this post Link to post Share on other sites More sharing options...
Fireonice Posted January 8, 2006 Posted January 8, 2006 (edited) dirty gas filter, dirty air filter, low tire pressure, dirty fuel ingectors (if u have em). Thous are the things i can think of off the top of my head. Edited January 8, 2006 by Fireonice Share this post Link to post Share on other sites More sharing options...
airman Posted January 8, 2006 Posted January 8, 2006 dirty gas filter, dirty air filter, low tire pressure, dirty fuel ingectors (if u have em). Thous are the things i can think of off the top of my head. 612550[/snapback] alright that's a start i'll get to work =) would it be a good thing to try some of that "STP Fuel system cleaner"? isn't that stuff just....really high octane gas? lol Share this post Link to post Share on other sites More sharing options...
hardnrg Posted January 8, 2006 Posted January 8, 2006 check your sparks are clean and whip out the feeler gauge on them to check the arc lengths are all dead on where they should be... you can lose a bit of power by a weak spark because it's dirty, the arc length is off, or as you have already kinda implied: a lack of juice... if it's the amp taking power away then i dunno, maybe you need a dual battery system or a capacitor... Share this post Link to post Share on other sites More sharing options...
BTSchnarfy Posted January 8, 2006 Posted January 8, 2006 Bad mileage can be a number of things. Fuel filter, fuel injectors, tune-up time, tire pressure, oxygen sensor (air/fuel mixture may be off). Kinda hard to pinpoint. How many miles are on it? When was the last tune-up? Share this post Link to post Share on other sites More sharing options...
cchalogamer Posted January 8, 2006 Posted January 8, 2006 Dependign on Milage, could be tune up time. New spark plug and plug wires will do wonders in many cases. Oh and Distributor cap....cant reemmber about the ignition system on Mom's jeep...hers is still getting the 17ish mpg so anyway. Share this post Link to post Share on other sites More sharing options...
Ste Posted January 8, 2006 Posted January 8, 2006 The number or years and how many miles on it are key. Like others said you may need to replace some filters and Get tune up like service applied to it. Im guessing you haven't changed the coolant, Transmission fluid and Brake fluid since you got it, You should also check Oil level and quality. Coolant Should be either Green or Red depending on if its extended Life or not. If its not a pure cooler or appears dirty it should be flushed and changed. (Don't forgot to check all radiator Hoses and Radiator Cap) Transmission fluid should be Bright red. If its dirty or not red you should have it flushed and replaced. (Im not sure sure if there are differen't colored transmission fluids, so Don't qoute me, bright red is just one I know of. Should also replace Filter) Brake Fluid Should be clear, if its not consider replacing it. (Brand new Brake fluid is clear, when most fluids get older they lose temparture ratting and their preformence ratting) Oil should be yellowish Brown, If its not, replace it with the reccomended oil in your owners manual.( Should also change the filter). If I Forgot to state in the above, all the colors I described is when the fluid Is new. So you can judge how bad of a condition your fluid is. You should also check your PCV valve and your Air filer, Cabin Filter also. I know its alot, but I had all that and much more done on my car recently. Preventitive maintence is the key to taking care of a car. Share this post Link to post Share on other sites More sharing options...
airman Posted January 8, 2006 Posted January 8, 2006 @Ste i have changed all of them recently actually. coolant: today, my top radiator hose busted so i all my coolant was gone. luckily it busted as i was pulling into my driveway so no overheating and melted gaskets =) oil was about a month ago. trans fluid probably 6 months ago, brake fluid was about 3 months ago when i replaced my brakes. when i pushed the caliper pin it pushed some fluid out and i knew it needed to be replaced heh. so basically i'm going to be checking my electrical system, i've got all the tools i need to check the spark plugs, i'll look up the right arc length in my handy dandy haynes manual. i'll check the fuel filter, not sure about how to check my oxygen sensor... tire pressure is fine 127k miles keep in mind that i do have an extended knowledge on cars however this kinda stuff i get kinda lost on. well, figuring it out for my self. but i know that it's progessively gotten worse so i've gotta do something about it =) Share this post Link to post Share on other sites More sharing options...
Ste Posted January 8, 2006 Posted January 8, 2006 Well good luck then, I just wanted to make sure you covered the basics at least. Share this post Link to post Share on other sites More sharing options...
bigred Posted January 8, 2006 Posted January 8, 2006 just wondering, but what would brake fluid have to do with MPG? also if the jeep is new enough I'd get it to a shop where they can hook up a computer to it and within seconds tell you EXACTLY what it needs Share this post Link to post Share on other sites More sharing options...
Ste Posted January 8, 2006 Posted January 8, 2006 just wondering, but what would brake fluid have to do with MPG?also if the jeep is new enough I'd get it to a shop where they can hook up a computer to it and within seconds tell you EXACTLY what it needs 612619[/snapback] Far As I know, Not much. However I was suggesting a broad range of preventitive maintenance. Share this post Link to post Share on other sites More sharing options...
ClayMeow Posted January 8, 2006 Posted January 8, 2006 I have a 1996 Jeep Cherokee 6cyl 4.0L automatic 4WD. since about 6 months ago my gas mileage has been steadily dropping. for the first ~2 years that i had it, it kept around 16-18mpg or so. however over the past 6 months it's dropped down to about 12-14mpg. what could cause this? it wouldn't happen to be my amp/sub that i put into my car about 3 months ago would it? 12w6v2 rockford fosgate 851S amp soooooooooo any suggestions of what it might could be? 612548[/snapback] my mom showed me an article awhile back that said blasting the radio, esp with an amp/sub actually does use some gas, but I dunno...I think it's a load of crap. I don't know much about cars though, so someone else can chime in Share this post Link to post Share on other sites More sharing options...
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