I've owned two 1997 Jeep Wranglers and eventually they both shared a common problem of rough idle, low fuel mileage, check engine light and and rough acceleration. Sometimes it would run fine but sometimes it had those symptoms. 1997 w/4 cylinder.

Check Engine Light/Misfire Due to Intake Valve Locks ...

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Jeep Liberty Check Engine Light/Misfire Due to Intake Valve Locks/Valves. ...Misfire cyc 4 and random cyc misfires, changed coil packs and plugs... sounds as if rod ... Light came on again (misfire on cylinder 4) - switched coil from 4 to 2. Light ...

Jeep Liberty Questions - Cylinder Misfire code - CarGurus

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CarGurusMay 27, 2009 - #4 misfire new plugs and coil pack on #4 light came back on after 300 miles if ... How come it stopped misfiring for 2-3 months, and now is back? ... I have a 2005 Jeep Liberty 6 cylinder, engine light came on scaned the codes ...

Liberty Cylinder Misfire / Computer issue? - JeepForum.com

This what I think is happening. Your engine is running rich because the ECM thinks it has too much air and so injects more fuel. When you now introduce air, by taking th e vacuum line off, the fuel mixture is now more balanced. Have you cleaned your MAF sensor? Also make sure your engine coolant is full.

A few things ,97;tune up, fuel filter,air filter,clan throttle body,put in tank some fuel injection cleaner good one not cheap.

check engine light?? i'd say check the O2 sensors...

make sure you put the right plugs in the fault is most likely the coil pack follow the plug leads from the spark plugs and you will reach the coil pack about £60

i would try replacing the crank sensor,its mounted behind the head of the engine on top of the trans bell housing,the connector for the sensor runs over to the passenger side of the engine near the fire wall,just follow the harness to the sensor,not bad to replace, and if its not your problem you can always return it,i have seen alot of these go bad,another way of telling is to crank it over and see if the check engine light goes off,if it doesnt the computer isnt seeing a crank reference,crank it for about 10 seconds,hope this helps

howdy, there are a few things on your 99 Accord that could cause that problem. usually all will eventually turn on the check engine light in time. make sure your check engine light is working when the key is first turned to run.

* a partially clogged catalytic converter.
* faulty O2 Sensor (Bank 1 Sensor1).
* low fuel pressure caused by a bad fuel pump, clogged fuel filter(in the tank) or a bad fuel pressure regulator on the injector rail.
*bad ignition switch which can cause intermittent stalls.

now i don't know which engine you have, (i'm guessing a 4cyl.) there were two 2.3L- 4cyl. engines (F23A1 & F23A4) and a 3.0 V6. but if you also have a rough idle or low idle miss, a jumped timing belt can also causing loss of power.

if you know anyone with a scanner that reads the computer datastream, see what the O2 Sensor (Bank 1 Sensor1) is doing & look at fuel trim readings. Also check backpressure on the converter where that O2 Sensor is screwed in.

please let me know if i have helped, totally confused or scared you to death! Good Luck!

Before changing you pcm try cleaning your egr valve. remove the valve and see if its stuck in the open position if so use a small pick to clean around the spring.

check your transmission fluid,the motor will stall when fluid is low

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