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2003 Mitsubishi Outlander - Very Low MPG


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pss2006
Novice

Dec 2, 2016, 7:53 PM

Post #1 of 11 (441 views)
2003 Mitsubishi Outlander - Very Low MPG Sign In

I am having some problems with low fuel mileage on my 2003 Mitsubishi Outlander LS - 131000 mi. I have done the following within the last three months;

Changed fuel filter
Changed air filter
New Bosch Iridium Plugs
Seafoam through vacuum line
New front o2 Sensor
Transmission flush
Cleaned EGR valve
Cleaned intake manifold
Removed Catalytic (Not illegal where I live, likely will reinstall since not clogged and no improvement.)
New PCV Valve
Oil change (synthetic)


The following things have been checked as to working;

Battery
Wires/Coils
Fuel Pump


I am not sure what there is left to do. I am getting around 12 MPG. All check engine code issues have been resolved and there is now no light. A couple of observations are an exhaust smell when parked after opening doors, a slight sputter coming from the exhaust, and occasionally the car wants to stall after starting for the first time in the morning and the pedal is hard. At times when I let off the gas it seems that the car is slowing down quicker than it should. I am changing the P/S pump soon as it is whing and the steering is hard, likely that is causing some resistance.

I have cleaned the injectors using a cleaner in the tank plus removing them and running carb cleaner through them. MAF sensor has been suggested to change but I am not getting any codes with it. I disconnected it and noticed a severe degrade in performance, since then I reconnected it. I suspect it is a sensor but before I start buying I would like some direction.

Thank you for your input.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 2, 2016, 9:20 PM

Post #2 of 11 (432 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In

You may be just wasting your time and money. The EPA rating for city is 18MPG. Nobody ever gets the rated mileage. Now you add to that it is winter and the fact that the car has over 100K miles now. You aren't that far off.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 2, 2016, 9:37 PM

Post #3 of 11 (425 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In

? You smell an exhaust odor at all it's not right and should be throwing codes if odor is out the exhaust and not just oil burning off pipes even PS fluid if leaking would and buzz from being low quickly - no codes for a leak if so + damage to PS if running it low.


MPG is so dependent on accurate measuring and how it's used don't count that yet if not over many routine known checks. Anything sitting still is getting ZERO MPG averaged in.


Bosch probably is not the right brand of spark plug for this.


Put it back as intended and read codes again with another reader or look for where odor is coming from. I doubt PS alone is causing fuel consumption issues rather ruined somehow and will be a problem if not already.


Brakes are hard if about to stall will lose power assist - no surprise alone.


Easy on just parts tossing and harsh cleaning solvents.


Taking converter off legal or not isn't helping anything and should be throwing codes just for that and an engine that wants to stall would effect power brake assist and a harder pedal plus your "dragging" complaint also.


Putting out exhaust is either misfire or that it's from almost stalling and poor performance.


Codes must be showing this or have been reset too recently?


T



kev2
Veteran
kev2 profile image

Dec 3, 2016, 8:41 AM

Post #4 of 11 (414 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In

 FYI - Removed Catalytic (Not illegal where I live, likely will reinstall since not clogged and no improvement
A heads up for all - If you live in the USA it is illegal to remove cat... federal regulation.
Having no engine light does NOT mean there are no codes.
Vehicle is stock? no miracle magnets, oiled air filters, wrong thermostats, tire size, suspension mods?
Suggestion - get a scanner to observe live data zero in on that stall after start - FT,s and ECT as well as o2 sensor voltages.


PS: driving style has a significant effect on MPG... speed limit, easy starts, no off road.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 3, 2016, 1:51 PM

Post #5 of 11 (400 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In


Quote
A heads up for all - If you live in the USA it is illegal to remove cat... federal regulation.


To the tune of a $25,000 fine.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



pss2006
Novice

Dec 3, 2016, 6:21 PM

Post #6 of 11 (388 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In

Thanks for the replies. The last code that came up was P0420 regarding the cat, there have not been any codes for days since removing it. My friend has the exact same car with around the same mileage, he says he gets around 250-300 mi per tank, I am getting 175 mi (this is highway driving). Given the overall low performance of the car and this issue has only been around for about three months there has to be solution, I use to get around 230 mi to a tank. Again my mechanic thinks its the MAF sensor but cleaning it has not helped, I do not want to spend money on the sensor on a maybe. I should mention that this car is located in Honduras, it is always hot and weather is not a factor here. Thanks.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 4, 2016, 1:24 AM

Post #7 of 11 (368 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In

Quote you ">>I should mention that this car is located in Honduras, it is always hot and weather is not a factor here.<<"


Wish you'd said that first off. This is going to need finding out what has been altered, messed with already before you got it and what country of origin it was built for you should find info on a door jam sticker.


Any engine wants the back pressure of its exhaust system to be right so get the converter back on and find out what the odor is - I suggested burned fluid/oil of some sort - find out.


Codes should be all over the place with this and probably need a much better reading device than you are using or your mechanic as it's not running properly so has to be throwing codes and do believe poor fuel mileage when any engine isn't running properly.


We have the cart before the horse if you will - it has to run properly THEN worry about MPG not that first.
Since you have another vehicle (your friend's) to look at then just by eye is it possible to compare one with the other that all things are hooked up as intended which is only good if the true exact same engine and model year.


Fuel - Climate: Do you even trust what you get for fuel or the quantity of it where you buy it? Understand climate is always warm to hot but an engine isn't warm at even a true 100F it's cold to it.


IDK - I think you may need to check that engine is healthy in total also at this point - compression test is probably in the mix here if it's OK to work with or full of troubles already? Next - take care of the PS problem it probably will be more than just a pump by now.


Then credible code reading. Having none now with converter missing already suggests it isn't communicating at all for this and would hope you can rule in or out certain failure or alterations that it may have that are all part of this running properly and getting performance including MPG as per how it was intended. Lots of unknowns still all over the place with this,
T



pss2006
Novice

Dec 18, 2016, 8:59 PM

Post #8 of 11 (317 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In

Thank you so far for your help. I have some updates. The car was throwing up a P0420 code referring to catalytic ennificeny. I know the issue is not the cat. I changed the coolant sensor as a precaution since it was cheap and easy, there has not been any improvement.

The car is originally from the USA and in terms of the motor is original. I do not see any wired modifications in terms of the engine, all parts including sensors are original.

It has been suggested to change the downstream o2 sensor, however I was under the impression that this was more of an emission only sensor and did not effect the fuel/air mix.

I have started to use high test gas, they say its 95 octane but I know its lower, I do notice that there is less engine knock (tin can rattle) when I use it. The compression is fine on the motor, it was test when I bought it and again a couple of weeks ago.

PS pump was bought from Napa and installed Saturday by them. I need to take it back since they did not bleed the lines correctly and there is air in it. The wheel is very hard to turn at idle and its lumpy (the rack has already been changed, feeling is new after the PS pump installation).

I feel the issue is a sensor but I'm not sure which. Car idles very rough (chugging) when the motor is completely cold and settles within a minute.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 19, 2016, 5:58 AM

Post #9 of 11 (308 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In


Quote
The car was throwing up a P0420 code referring to catalytic ennificeny. I know the issue is not the cat.


Of course the problem is the Cat. You don't have one.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



pss2006
Novice

Dec 19, 2016, 6:37 AM

Post #10 of 11 (299 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In

I forgot to mention that the cat was put back and the flex pipe was changed. There are also no leaks in the exhaust system.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 19, 2016, 7:22 AM

Post #11 of 11 (294 views)
Re: 2003 Mitsubishi Outlander - Very Low MPG Sign In

It's still a bad Cat causing the code.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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