I have a 1999 Jeep Grand Cherokee V8 and it gets 200 miles per tank and will not kick down on highway or around town. WHat could be causing this problem?

When you say it loses power, do you mean electrical power or engine power ?
You would need to look at the fuse boxes for a loss of electrical power, and use a scanner or code reader to check the computer for trouble codes for a loss of engine power.

It is typically 10 drive cycles and could take anywhere from 2 to 5 days depending on the type of driving you do. Try to take the car on the highway for a few miles, get off the highway, shut it down for a while, then do some local street driving.

It just depends on your tank size. You probably get about 15 -18 miles per gallon. 13 gallon tank would be around 200 miles. 15 gallon tank around 232 miles.

this might help you, Tim:

http://www.fueleconomy.gov/feg/noframes/16355.shtml

Computer controlled transmissions can get confused at times, from my personal experience. If the problem doesn't happen again, I would ignore it. If it happens all the time, it's most likely the transmission computer. Other things could be the shift linkage, engine vacuum leak, speed sensor, etc... Hope this helps.

Your gauge is reading high ... I think you are out of gas. You should calculate your actual Miles Per Gallon - find out what the capacity of your tank is and fill accordingly. For esample, you actually get 15 miles per gallon, your tank is 20 gallons - you should be able to drive about 300 miles between fillups. At 250 miles, start looking for a station.

who installed the CSM, sounds like it was installed incorrectly?

Also, are your battery connections tight?

Problem solved by the dealers service department. Thanks

Wide tires make less gas millage, get narrow wheels, let the car accomplish speed slowly from 0 to 30, look at air filter,if shortly replaced, oxygen censor, 15 miles is normal 16 miles per gallon is good for a V8

My Answer:

Poor gas mileage can be a result of many many things.

First of all you need to find out what is the factory normal gas mileage for your model year Jeep SUV. It should have said on your window sticker if you bought it brand new. If you are a 2nd or 3rd owner then a Jeep dealer would have info. Google search will tell you as well, and only takes a couple minutes to find.

I did a quick Google search and for a 2003 Jeep Grand Cherokee with a (4.7L V8 engine) the average mileage is roughly 14 mpg.

Not sure what engine you have as to options, etc?

How you drive will greatly change that number up or down depending on a number of driving and driver variables.

A few being -

Driving habits?

Tire pressures?

Engine tuned up?

Lube & oil/filter changes (every 5,000-7,500 miles? Air filter changes (every 10,000-15,000 miles)? Read your auto manual for exact recommended intervals.

How many people in the SUV on average?

Are you towing anything?

Type gas you are burning - BRAND? (See injectors below)

Area you are driving in (hills and valleys verses flat out,
etc)

Jeeps in general don't have a good track record for great mileage, and rough engine idling is always a clue that your fuel injectors are dirty. Typical on all Jeeps with port fuel injection systems! On Jeeps with dirty fuel injectors your mileage will go way down accordingly. If your not putting at least a 12 oz bottle of say Walmart brand Super Tech Fuel Injector Cleaner (~ $1 each) in your gas tank religiously every logged 1000 miles, or every 2 tank fill ups, then you are just inviting dirty fuel injectors and POOR fuel economy!

My 1993 Ford XPLR with a 4L V-6 engine (and ~ 160,000 flawless driven miles) gets roughly 22 miles per gallon on the highway with cruise control on, and about 17 around town on average. I religiously put a 12 oz bottle of the above injector cleaner in my gas tank every 1000 miles!! Of course I do all my own tune-ups, general repairs, and suspension maintenance (shocks, O2 sensors, trans oil changes, lube & oil/filter changes, code reading and clearing, etc) myself and it shows! I don't trust repair shops except for say Tires and Balancing at SEARS.

Hope that helps ease your mind about gas mileage as it relates to your Jeep there.

Frank