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Green tune - Speedometer off
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=79912		 Page 1 of 1
Author:  jrsavoie [ Mon Aug 18, 2014 12:09 pm ]
Post subject:  Green tune - Speedometer off
My speedometer is off about 4 mph at 55 mph. It shows I am going faster than I am. According to both our GPS and the flashing road signs that show your speed.

Can I take this to a dealer to get the speedometer reset?

What are my options?

We are not getting the fuel mileage I wish and I need to figure out exactly What mileage we are getting before I get to involved.

We are currently getting 25 mpg not accounting for the fact the speedometer shows us going faster than we are. I would imagine that means the odometer is also showing us going farther than we actually have when we calculate the fuel mileage.
Author:  papaindigo [ Mon Aug 18, 2014 12:56 pm ]
Post subject:  Re: Green tune - Speedometer off
Different issues here:
1. speedo and odometer can both be off by +-5% and meet standards; the 2 gauges get readings from different sources IIRC so can individually be off by a different amount in the same or a different direction; changing to any tire other than OEM stock can alter both readings
2. only accurate way to determine real speed and miles traveled is by GPS; speed can be checked almost instantly but to check miles traveled by GPS vs odometer I prefer at least 2 runs as straight as possible for at least 25 miles.
3. any mpg obtained from the EVIC is wrong; only accurate mpg is GPS miles or odometer miles you correct based on GPS readings; further mpg for runs of less than say 200 miles are likely wrong and it's best to fill tank full to the brim or use the same pump and fill to when the pump cuts off if you want accurate figures
4. driving style, terrain, weather, wind, etc all impact mpg - generally pre-GDE EcoTune I got 18 town 27 hwy and post tune 22/31 sometimes more sometimes less.
5. with DCJ or equivalent scan tool(s) speedo can be adjusted a bit but whether enough to solve your issue I don't know.
Author:  jrsavoie [ Mon Aug 18, 2014 1:06 pm ]
Post subject:  Re: Green tune - Speedometer off
Thanks. I have not checked the odometer against the GPS yet. Not for lack of opportunity - just old timers disease and forgot to remember.

After I check the odometer against the GPS would I be able to take it to a dealership to get the speedometer to read closer? Would the Green tune have any effect on doing that or not?

The tires were down sized from 225/75R16 to 235/70R16 I thought the 2356/70's would be a bigger diameter tire. They are actually a smaller diameter tire.

wE DO NOT GET MUCH TOWN DRIVING HERE. The nearest town is 7 miles away.

papaindigo wrote:
Different issues here:
1. speedo and odometer can both be off by +-5% and meet standards; the 2 gauges get readings from different sources IIRC so can individually be off by a different amount in the same or a different direction; changing to any tire other than OEM stock can alter both readings
2. only accurate way to determine real speed and miles traveled is by GPS; speed can be checked almost instantly but to check miles traveled by GPS vs odometer I prefer at least 2 runs as straight as possible for at least 25 miles.
3. any mpg obtained from the EVIC is wrong; only accurate mpg is GPS miles or odometer miles you correct based on GPS readings; further mpg for runs of less than say 200 miles are likely wrong and it's best to fill tank full to the brim or use the same pump and fill to when the pump cuts off if you want accurate figures
4. driving style, terrain, weather, wind, etc all impact mpg - generally pre-GDE EcoTune I got 18 town 27 hwy and post tune 22/31 sometimes more sometimes less.
5. with DCJ or equivalent scan tool(s) speedo can be adjusted a bit but whether enough to solve your issue I don't know.
Author:  papaindigo [ Mon Aug 18, 2014 1:28 pm ]
Post subject:  Re: Green tune - Speedometer off
I cannot wap my head around what that change in tire size would do to either or both speedo or odometer but there certainly would be an impact. I think a dealer can adjust for tire size to correct speedo, not odometer, but don't know how much - just drop by and ask.

As to what adjustments Keith can make in a GDE tune best email him. I do know he has been able to make the EVIC "less" inaccurate and it's inaccuracy more predictable.
Author:  CATCRD [ Mon Aug 18, 2014 11:43 pm ]
Post subject:  Re: Green tune - Speedometer off
Larger tires will make your speedo read slower than your actual speed, and your odo read fewer than actual miles traveled.
Most KJs were off on both accounts as delivered, with factory tires.

GDE can't adjust either, since the revs/mile numbers are in the BCM, not the ECM or TCM that they tune.
Since you have a 2006 you will need to go to a dealer to have them adjusted. They are separate adjustments.
Author:  jrsavoie [ Tue Aug 19, 2014 7:17 am ]
Post subject:  Re: Green tune - Speedometer off
When I talked to the service manager he didn't sound like he knew much about it. He said he didn't know if they could be adjusted or not.

Kind of scares me. How much can they mess up, if they plug into the computer, start making changes and mess something up?

Does anybody know of anyplace close to me that I could go to for this?

And don't say Pearl Chrysler Jeep Dodge in Peotone, Illinois. They are the ones that ruined the engine and cost us tons of money that didn't need to be spent
Author:  Rich [ Tue Aug 19, 2014 11:18 pm ]
Post subject:  Re: Green tune - Speedometer off
jrsavoie wrote:
When I talked to the service manager he didn't sound like he knew much about it. He said he didn't know if they could be adjusted or not.

Kind of scares me. How much can they mess up, if they plug into the computer, start making changes and mess something up?

Does anybody know of anyplace close to me that I could go to for this?

And don't say Pearl Chrysler Jeep Dodge in Peotone, Illinois. They are the ones that ruined the engine and cost us tons of money that didn't need to be spent


What a fool! Any Chrysler, Jeep, Dodge, independent shop, or Joe Bob Briggs with a DRBIII can do the job. Takes about 5min, but you'll be paying for .5hr if they are anything like my local shop. In the DRBIII, choose "Transmission" then "Pinion Factor" there are two options, one is for preset tire sizes (which are always wrong) and to manually input the true rev/mil of your tire. You can find this by going to your tire manufacturer's website and looking in your tire's specs.
Author:  tjkj2002 [ Wed Aug 20, 2014 8:05 am ]
Post subject:  Re: Green tune - Speedometer off
Rich wrote:
jrsavoie wrote:
When I talked to the service manager he didn't sound like he knew much about it. He said he didn't know if they could be adjusted or not.

Kind of scares me. How much can they mess up, if they plug into the computer, start making changes and mess something up?

Does anybody know of anyplace close to me that I could go to for this?

And don't say Pearl Chrysler Jeep Dodge in Peotone, Illinois. They are the ones that ruined the engine and cost us tons of money that didn't need to be spent


What a fool! Any Chrysler, Jeep, Dodge, independent shop, or Joe Bob Briggs with a DRBIII can do the job. Takes about 5min, but you'll be paying for .5hr if they are anything like my local shop. In the DRBIII, choose "Transmission" then "Pinion Factor" there are two options, one is for preset tire sizes (which are always wrong) and to manually input the true rev/mil of your tire. You can find this by going to your tire manufacturer's website and looking in your tire's specs.

The DRBIII will not do anything for his '06,will not even communicate with it.
Author:  Rich [ Wed Aug 20, 2014 9:58 am ]
Post subject:  Re: Green tune - Speedometer off
TJ you are correct, the DRBIII won't talk to his '06...

Maybe next time you be a touch more helpful and correct my post to say the dealer will be able to make the change using the Starscan. :roll:
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