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Old 12-29-2014, 05:12 AM
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05 overland bad mileage

good morning,
new to me 05 overland. factory original 28,000 miles. it lives in the carribean at a vacation home. I know the car from new as it belonged to my neighbor who has imported a new one so I bought the old one. it had 4 mil codes... 2 o2 sensor and 2 evap. new sensors fixed those two and a gas cap fixed one of the others. the 4th is apparently a purge valve ( whatever that is ). the car runs and drive fine. when I got it the mileage was terrible 8-9 mpg. the new sensors made that 11.5 which is what the display says and is confirmed manually. in an effort to optimize it the car is driven conservatively in the extreme...
I look at the specs for this car new and they claim 14 or so " city" and I would expect that around here as there are really no roads where speeds exceed 40 mph for more than a few seconds. I am a professional mechanic , in the business for 30 years before I retired here albeit primarily in european cars and race cars so while I know my way around , so to speak, I don't have any jeep overland " experience " . short of that one evap code the car runs as new , all the temps and pressures are good, aircleaner is fresh and not a hint of anything wrong in a conventional sense. the ambient air here is 75 to 85 so its not like the thing starts and runs cold for any length of time...

so the question becomes... are these things just that bad on fuel or are there known issues to look for in the sensor array that can cause this without a code showing up ? the exhaust smells " clean " so I am sort of dismissing ( but not ruling out ) clogged converters. there is no formal emissions testing here so the car has never been sniffed and that is on my list of things to do this week but I am curious about the known issues scenario. seems hard for me to believe this car can be this inefficient... I had carbureted 400 hp muscle cars back in the day that were better than this on fuel...

steve

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  #2  
Old 12-29-2014, 06:22 AM
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Re: 05 overland bad mileage

Welcome to the garage Steve.
Did you check the plugs for condition? Eventhough the milage is low, the slow driving can leave quite some deposits on them.
Also did you check the new O2 sensors with a scanner and see how the STFT figures are?
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Old 12-29-2014, 06:33 AM
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Re: 05 overland bad mileage

Quote:
Originally Posted by Frango100 View Post
Welcome to the garage Steve.
Did you check the plugs for condition? Eventhough the milage is low, the slow driving can leave quite some deposits on them.
Also did you check the new O2 sensors with a scanner and see how the STFT figures are?
no and no. the car runs so well that , intuitively, I simply felt the plugs were not a likely suspect.. solid steady idle, crisp off idle transition etc... so they were not on my immediate suspect list . I used good quality o2 sensors and the mil codes went away and the mileage vastly improved back to borderline acceptable so I didn't manually check the voltages under the assumption that if they were out of spec then the light would have come on and no improvement would have occurred. the fact is that I haven't materially done anything at all beyond what I descr9ibed simply because , professionally , I would simply whip out the workshop manual and spend a boatload of time checking everything before trying anything beyond what I knew already to be wrong... what I was am still hoping for is the ubiquitous " oh... the ALL do that " sort of answer. there are two things that nag at me a bit... one is the fuel quality here is poor in general and second, the car ran with the bad 02 sensors for probably 2 years or more. that means it ran rich for that time. combine that with the bad fuel and I wonder if the converters are plugged up. certainly the exhaust system on this is anemic for a v-8 in any case and restricting it further could make the mileage much worse by 3 or 4 mpg easily... but I don't want to talk myself into anything...
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Old 12-29-2014, 06:46 AM
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Re: 05 overland bad mileage

If it ran for soo long rich, there is a change that the cats are the problem. It would only be interresting to see what the fuel trim figures are at the moment, so that you can see if there is some underlaying problem.
Regarding the evap/purge solenoid, its just a solenoid valve which connects the EVAP canister to the engine inlet. The PCM will pulse this valve to create a vacuum in the canister. Attached how the valve looks like.
Attached Files
File Type: pdf 05 evap-purge solenoid.pdf (72.7 KB, 7 views)
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Old 12-29-2014, 06:54 AM
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Re: 05 overland bad mileage

Quote:
Originally Posted by Frango100 View Post
If it ran for soo long rich, there is a change that the cats are the problem. It would only be interresting to see what the fuel trim figures are at the moment, so that you can see if there is some underlaying problem.
Regarding the evap/purge solenoid, its just a solenoid valve which connects the EVAP canister to the engine inlet. The PCM will pulse this valve to create a vacuum in the canister. Attached how the valve looks like.
do you know if thatis an expensive component and what manual did that page come from ? I need one of those for this car if im going to keep it.
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Old 12-29-2014, 09:17 AM
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Re: 05 overland bad mileage

Rockauto.com has the purge solenoid valve for your jeep for around USD 40. But first check if the valve is the problem, or maybe the connector or wiring.
The manual i found online for free, only donīt remember where i found it. Try some googling.
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Old 12-29-2014, 09:20 AM
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Re: 05 overland bad mileage

Quote:
Originally Posted by Frango100 View Post
Rockauto.com has the purge solenoid valve for your jeep for around USD 40. But first check if the valve is the problem, or maybe the connector or wiring.
The manual i found online for free, only donīt remember where i found it. Try some googling.

looked around for the manual but want the factory one and not the aftermarket and your page looked like the factory one. no prob, ill find it.
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Old 12-29-2014, 10:00 AM
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Re: 05 overland bad mileage

If you feel that the fuel quality is poor that would impact your fuel economy.

Also, has the throttle body / fuel injection system ever been cleaned? Based on the fuel quality and how you describe the vehicle being used this may be beneficial.
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Old 12-29-2014, 10:11 AM
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Re: 05 overland bad mileage

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Originally Posted by MDBones View Post
If you feel that the fuel quality is poor that would impact your fuel economy.

Also, has the throttle body / fuel injection system ever been cleaned? Based on the fuel quality and how you describe the vehicle being used this may be beneficial.

my three other cars all get normal fuel economy so the quality of the fuel is one of energy content rather than contamination. I use the same fuel in my boat which has motors that make 700 hp each on the dyno with good fuel and about 645 with the local fuel and the filters are always clean. its just low octane fuel. and at 28,000 miles im pretty sure that the injection doesn't need anything at all considering that it idles like a swiss watch and if the fuel system is dirty the first place it shows up is at small pulse widths... of course anything is possible but some things are just less likely than others.
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Old 01-02-2015, 11:42 PM
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Re: 05 overland bad mileage

Quote:
Originally Posted by MDBones View Post
If you feel that the fuel quality is poor that would impact your fuel economy.

Also, has the throttle body / fuel injection system ever been cleaned? Based on the fuel quality and how you describe the vehicle being used this may be beneficial.
What is the correct way to clean this? My manual on my 07 wk or maybe wkjeeps says you are not supposed to clean the throttle body because if some coating. Is it different for the v8s? Dealer always comes up with a $200 service to try and sell me when I know they will just squirt in some throttle body cleaner and dump some bs injector cleaner into the gas tank and call it good.
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Old 01-03-2015, 06:21 AM
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Re: 05 overland bad mileage

Quote:
Originally Posted by beepbeepimajeep View Post
What is the correct way to clean this? My manual on my 07 wk or maybe wkjeeps says you are not supposed to clean the throttle body because if some coating. Is it different for the v8s? Dealer always comes up with a $200 service to try and sell me when I know they will just squirt in some throttle body cleaner and dump some bs injector cleaner into the gas tank and call it good.
for all things like this you need to consult the factory workshop manual... not an after market manual or any other source. the factory workshop manual will define very precisely this and any other procedures that they consider critical and where generic or normal shop procedures may cause damage. you would be surprised how often this sort of thing happens usually on electronic components where people will ground something with a test light and kill it or hot wire 12 v to a 5 v circuit as a test... if you are doing your own work, the factory workshop manual is the first tool you buy.
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Old 01-03-2015, 09:27 PM
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Re: 05 overland bad mileage

Is this a Hemi or 4.7 L? The Hemi has an electronic Throttle Body and the 4.7 has a manual. The electronic is VERY sensitive to cleaning and the 4.7 is not. Proceed carefully with the electronic TB.


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