Re mapping?

Will

Will

Core Member
I have a 55 Jeep Grand Cherokee 3.0 CRD. The thing is bloody awful on fuel for a diesel, the dash shows 20.5 per gallon if I'm lucky. Beginning to wish I'd gone for the V8 petrol one! I can only assume the full time four wheel drive isn't helping because the same Merc V6 in an E320 yields high 30's apparently.
I've had a few people suggest getting it re-mapped as it will improve performance and fuel economy.
It is powerful enough for what I need, but it would be nice if it wasn't so thirsty.
I've had nothing to do with re-mapping and would welcome any knowledgeable comments. Is there likely to be any improvement on fuel thirst and are there any possible negatives?
 
AmericanThunder said:
Drop the front prop shafts out for one tank to test?
Click to expand...

It's interesting you should say that. What I didn't think to add until after I posted was that as a comparison, before this Jeep I had a Nissan Terrano 3.0 SVE oil burner. That had selectable RWD only (which I always left it in for daily use). That regularly turned in 30+.
That did make me think of dropping the front prop off this Jeep as a test. But not sure if that will work or will it just spin the front output from the transfer box and not put any drive to the rear?
It does have a diff lock switch, but pretty sure that locks left/right wheels together as well as front/rear. Also, it engages the low ratio too I think.
 
Mapping will likely have an effect but the percentage is small. You aren’t going to see a 50% increase to 30mpg. Maybe upto 22mpg so how long would it take to recover the costs of the remap? Depends how many miles you drive.
Tyres would help too, as would tyre pressure. Increase tyre pressure to reduce rolling resistance but you will sacrifice grip and beware your insurance in the event of an accident.
Weight loss? Back seats, spare tyre, in car entertainment. All stuff you can lose.....
Just brain storming really.
In 2007 we bought a virtually brand new Chevy Lacetti. The mpg was pretty dire so we converted to LPG at 20000 miles and it did most of the next 165000 miles on LPG. Instant fuel cost savings. Can you LPG a diesel? Don’t know but with my mileage at the time I calculated a return on investment of 9 months and did it in 8!
 
I think the 'MPG increase after remapping' its something a guy says to the wife to justify the power increase.

Fine tuning every part of the fuel map for the mods/tiredness of the engine could help a bit, but I don't think you will see huge gains. If all the fuel is being burnt fully there isn't much more that can be done.
Unless someone is taking your jeep out for a spin and using the fuel, then perhaps try hiding the keys. :noidea:
 
I tend to agree with what's been said, it is probably unlikely that re-mapping would much improve the consumption. And aside from basic things like keeping the Tyres nice and firm, shedding unnecessary weight and perhaps changing my driving style, what it does it what it does. I did briefly search re LPG and apparently it is possible on a diesel but is quite involved.
 
Sent the work van for a remap.

van_remap.jpg
 
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