Trip computer accuracy?

scooter_scum · **Posted:** Fri Jul 31, 2009 10:30 am

I've just purchase a beautiful 2008 CRD. Plan on taking it on our first family trip. I have yet to put a full tank through it, curious how accurate the Jeep trip computer is..

1. MPG average calculate?
2. Distance to Empty?

Wondering how much I can depend on the data. Can I trust the Distance to Empty??

Thanks to everyone that make this forum so valuable.

RTStabler51 · **Posted:** Fri Jul 31, 2009 11:32 am

My EVIC is roughly 3mpg off.
Once the fuel light comes on, you have about 2 gallons of fuel left (I've gone about 50 miles with it on.).

CRDMiller · **Posted:** Fri Jul 31, 2009 11:58 am

... 3.0 merc td? aka a GC?

Anyway you should hand calculate your mpg and find your error, there will be error. Get your mileage error with gps or similar also. (common on kj/crd maby not on GC)

As far as remaining, goes, it's a function of your mpg, and cap of your tank, neither of witch are likely to be accurate. your doubly screwed.

Let me give you an example. Evic says i'm averaging 33 mpg, my fuel light comes on (0 miles to empty) i continue driving 100 miles. When i fill up i add in 22.2x gallons. crd kj is 20 gallon tank. YOU tell me.

Pay attention to the sweep of your fuel gauge. In my case, it sweeps below the e, when off, and i figure that's EMPTY. It also sweeps above the f.

It's a cluster of fun. Bottom line is they are all different, every freaking vehicle. Trial and error is how you get there. Carry a 5 gal tank of diesel with you and drive it till you loose prime. I hope you have a lift pump, also i would not make a habit of doing this, IP's don't like to run dry, no fuel = no lube.
But what if next time your fuel light is on, you think, well i went 100 mi last time no problem. So you shoot for 80 mi, you run out of fuel. Headwind vs tailwind 26 mpg vs 33. Not good.

Here's something else. I typically fill up within 1-5 miles of my fuel light coming on. Sometimes this is 17 gal, sometimes it's 20+ Yeah.

I figure your probably going to want to stop within 600 miles anyway (30 mpg @20 gals), may as well get fuel while your doing that. That's eight hours at 70 mph. (30 mpg possible at 70)

scooter_scum · **Posted:** Fri Jul 31, 2009 2:45 pm

Well, very curious. That is wild that the reserve ding has so much variation. Well, it will be an adventure. I don't plan on running it out of fuel. Have no idea if I have a lift pump or not. (now I know what the lift pump thingy is after all ).

Appreciate the responses.

ac5501 · **Posted:** Fri Jul 31, 2009 4:23 pm

scooter_scum wrote:

I've just purchase a beautiful 2008 CRD. Plan on taking it on our first family trip. I have yet to put a full tank through it, curious how accurate the Jeep trip computer is..

1. MPG average calculate?
2. Distance to Empty?

Wondering how much I can depend on the data. Can I trust the Distance to Empty??

Thanks to everyone that make this forum so valuable.

I'm guessing you mean a "beautiful 2006 CRD". If you actually did purchase "beautiful 2008 CRD", I would be looking to move to CO asap

nursecosmo · **Posted:** Fri Jul 31, 2009 5:06 pm

If it is a Grand Cherokee, 2008 would be correct but the forum would be wrong. Try http://crdtalk.com/

CATCRD · **Posted:** Fri Jul 31, 2009 9:48 pm

FYI I just filled up when the low fuel light came on and squeezed in 20.7 gallons - 2 shy of my biggest fillup, so yes you've got about 2 in the tank when the light comes on.

unwritten · **Posted:** Sat Aug 01, 2009 12:50 pm

As CRDMiller stated, the "Distance to Empty" is calculated strictly off of the "Average MPG" from the computer. The distance to empty would only be 100% accurate if you were getting the same Average MPG the whole time...

Lancer · **Posted:** Sat Aug 01, 2009 1:17 pm

Once the light comes on, I won't go further than 20 miles before refueling (if possible!)

scooter_scum · **Posted:** Sat Aug 01, 2009 1:36 pm

Not to sound too stupid, but Is the distance to empty when you go on reserve (the reserve light goes on). Or is it approximately the number of miles to no fuel?

When I was in Hawaii, I rented a JEEP. Returned the car to the rental agency with "0 miles" to empty. I'm assuming I can safely reach Zero on the CRD.

My Nissan Altima trip computer is very very conservative. Distance to Empty of ZERO still has 5 gallons of fuel in the tank. Being that conservative borders on useless.

Sir Sam · **Posted:** Sat Aug 01, 2009 1:41 pm

scooter_scum wrote:

Not to sound too stupid, but Is the distance to empty when you go on reserve (the reserve light goes on). Or is it approximately the number of miles to no fuel?

When I was in Hawaii, I rented a JEEP. Returned the car to the rental agency with "0 miles" to empty. I'm assuming I can safely reach Zero on the CRD.

My Nissan Altima trip computer is very very conservative. Distance to Empty of ZERO still has 5 gallons of fuel in the tank. Being that conservative borders on useless.

Amount to reserve, generally I think there is about 2-3 gal left when the DTE is 0.

scooter_scum · **Posted:** Sat Aug 01, 2009 10:47 pm

The perfect answer!!! Whew...

danoid · **Posted:** Mon Aug 03, 2009 11:25 am

What I like is climbing on the freeway after filling up. Distance to empty starts increasing...

scooter_scum · **Posted:** Tue Aug 04, 2009 10:37 am

Pretty boring post but, my first tank of mixed city and highway. I filled when my Distance to Empty went to Zero. Here are the stats:

Miles 436.5 (stock tires -- based on Odometer -- yes there may be errors)
Gallons 18.4
Computer MPG 24.8
Calculated MPG 23.7
Error +4%

Not too bad. Love the range this thing is capable of. Again really appreciate all the help!

Trip computer accuracy?

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