My first cherokee. 1998 4.0 XJ.

I don't think I've ever had a car as thirsty as this including my big old 3ltr Landy, 3ltr 3000gt and my audi.

I know she's heavy but I've used more fuel in two days than I would in a week of driving any of my other cars. Is this normal? Are Cherokees really thirsty?

Just round town driving.

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Checked for tripped codes? Biggest cause for mpg dropped I've had was when I had an O2 sensor fail (upstream). I usually get over 20mpg on the highway and 17-18 on or county roads. Went from 20+ down to 13 when the sensor failed on a trip. No CEL showed.

 

I assume I need to get her plugged into a diagnosis machine?

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Yep. If you don't know anyone with a handheld go to one of your local parts stores. Many will scan for free although the last I saw our local Advance Auto (only one in town) wasn't doing it due to the virus issue.

 

It's hard to give you a number for urban driving as it's so variable. For rural driving I get about 3.5 miles / litre driving "briskly" which isn't too painful on gas @ 52.7ppl
I haven't run a full tank of petrol for years but ISTR filling up at 200 miles because the fuel gauge was broken (it was a 96 and impossible to get a new sender) but 250 was possible at a steady 70.

My 97 is on gas and I'd thoroughly recommend getting a good conversion done if you've got an LPG supplier nearby.
There's plenty of info on here: https://www.lpgforum.co.uk/

Otherwise, check the coolant temp sensor and prepare to make friends with the local garages!
Remember that most people on here are talking in US Gallons.

 

Hmmm. Don't know how I didn't catch on that he is an "out of towner". lol

 

We move amongst you.....

 

Just fine by me. The more (gear) heads the better. Got to keep these XJ's alive.

 

Hey All, So when I say she's thirsty I mean she's really really thirsty. Like something must be wrong.

In the last 3 days, I've used £40 of petrol, at £1.10 per litre.

I've done 35 miles on a motorway and roughly 8 x 3.5-mile trips to the office and back.

So the maximum of 63 miles.

£40 / £1.10 = 36liters = 7.99 gallons

63 Miles divided by 7.99 Gallons = 7.88 MPG

On the way back from the office today I nearly dropped an entire bar on the fuel gauge.

I've only just bought her 4/5 days ago, so just getting used to her but that MPG is what I'd expect in a monstrous V8, not this. In comparison, I'd top my 300TDI 110 Landrover up with £20 every Monday and did more distance on a daily basis. She was huge, with massive offroad wheels, always carried two spares wheels, winchs, jacks and weighed a lot.

@dave1123 You've been right by the other problems I've been having, any ideas on this one as well?

 

Remove the spark plugs and see what the gap is and they're condition. When I first got my '96 (second owner with 98K miles on it) the mpg was around 10mpg. Found the plugs were the original ones from the factory. The electrodes were literally gone but even so the vehicle ran fine. New plugs put my mpg where it should be. A complete tune would be a good start.

 

It's hard to tell unless you get active data with a scanner and check fuel trim, but I'd suspect your 02 sensors need replacing. I get about 10 to 12 mpg with my XJ in the winter delivering newspapers, which is constant stop and go on a route that's only between 45 to 50 miles. If I just stick to street driving, it gets around 16 mpg. I can't do the math to convert to liters per kilometer. Oversize tires and axle ratios also enter into the equation. I really wish you'd put your vehicle data into your signature because it this point, I haven't get the time to go back thru the posts to remember what you're driving. If you're running oversize tires with 3.07 gearing, that has a lot to do with it. Maybe someone stuck the wrong injectors in it.

This may seem picky, but Champion spark plugs work best in jeeps. NGKs are good, but I don't remember the number for the early ones. The 00-01s take ZFR5N because of the waste spark system.

 

try this. I have one and its awesome. really helps me figure stuff out

https://bafxpro.com/products/obdreader

Download one of many apps available to your phone to see what the reader is pulling up. I use "TorquePro" from the playstore. There is a free version and a $4.99 version. Not sure if the paid one has more use or what, but I get along with the free one just fine. It shows you codes, you can delete codes, and it shows you ALL kinds of parameters about how your vehicle is running.
I think they make them for Apple as well, if you have one of those things...

You can use it on multiple vehicles as well. Its not like a tuner that is VIN locked.

This makes me want to get in there and check my spark plugs, O2 sensors, etc.... I think I get about 14-15 MPG with about 60-70% of that cruising at 60MPH or so. I feel like I should be getting a little better than that... Also need to check my tire pressure. They look a hair low.

 

You know, I always got around 16 to 18 mpg with my WJ on average, then I did a round trip of about 200 miles on the NYS Thruway to Rochester and back to Syracuse with only about 25 miles in Rochester before returning, 90* day, light breeze, 70 mph, no A/C and all the windows down. To my shock and amazement it got 27.4 mpg! That's the one and ONLY time I got mileage like that! Oh, and I used the same fuel pump before and after the trip. Also the highway is very flat between those two cities.

 

Sorry bud, signature should be updated now. Im guessing the gearing is standard size.

 

I can see the co2 sensor going into the catalytic convertor, is there any other sensor and where is it?

Also do I clean or replace these?