Howdy y'all,

This is actually the first time I've posted a thread on the forum.

I bought a Deep Blue Metallic 2007 Mitsubishi Outlander LS 4WD with the Sun & Sound Package on January 20th here in Minneapolis. Before they let me drive it home, the dealership (a highly reputable Dodge dealership) changed all the fluids and installed fresh spark plugs/wires.

The CEL first came on about two weeks after I bought the vehicle; the code was for a misfire on Cylinder 4, and I was getting poor gas mileage. I replaced the cylinder boot, and the CEL disappeared. Around the same time, I also replaced the stock air filter with a K&N filter (which, by the way, makes a noticeable difference in acceleration and power).

About five days later, the CEL came back on again, and was on/off for several weeks. Of course, every time I went to go to O'Reilly's to have them troubleshoot the code, it would vanish.

The CEL then came on around mid-March and stayed on continuously. I finally got it back to O'Reilly's and the code was for the fuel mixture being too lean, and for a faulty TPS. This entire time, I'm only getting about 17-18.5 mpg in mixed city/highway driving.

The ****ty part about the TPS is that you can't just replace the sensor, you have to replace the entire throttle body assembly. I called the local Mitsu dealer, and a new one is $750. SEVEN HUNDRED AND FIFTY DOLLARS FOR A PART I CAN HOLD IN MY HAND 0.0

Needless to say, I did some hunting on Car-Part.com, and I lucked out and found a tested, functional throttle body from a salvage yard about an hour and a half away for $95. I bought it, went and picked it up, it installed last week, got a fresh oil change, no codes whatsoever, and I'm STILL getting abysmal gas mileage in the 18 mpg-ish range

I've put about 10,000 miles on my Outlander since I bought it; I'm kind of wondering if perhaps all that driving with the faulty throttle position sensor didn't cause my plugs to get fouled because of the constant improper fuel mixture?

Any ideas on what could be wrong/how to remedy this would be great, because I'm getting pretty discouraged with the gas mileage. I sold my 2002 Dakota Quad Cab pickup to buy this for better mileage, and thus far, I'm only getting a few MPG better than I did with my truck... and if I can't figure this out, then my Outlander is gonna get traded back in for a full size truck, there's no point in driving a midsize crossover vehicle that gets the same mileage as a full size pickup :/

 

Is it the 4 Cylinder or the V6?

Couple of interesting things in your statement above, there are no plug wires in these cars, it is COP coil on plug ignition. There is no TPS in the regular sense. The gas pedal position sensor sends a sign to the ECM engine control module, which has an actuator attached to the throttle plate inside the throttle body. If there was a cable from the pedal then you would have a TPS, however the MIVEC is far more advanced system as it has to change the fuel mix @3600 RPM when the valve profile changes. If you have a V6, the rear plug change requires removing the throttle body and it is possible something happened to it when it was reinstalled? Also, the transmission fluid is like $17 a quart for DiaQueen JT2 (or JT some number) and it takes 8 quarts to change, plus you have to disconnect the trans fluid cooler lines to properly change all the tranny fluid. My fuel economy was in the same range as yours until I added some Seafoam fuel cleaner, that stuff is amazing. I also followed the complete process to change the trans fluid with the correct variety (I suspect my dealer did it wrong last time I paid them to flush it). Hope this helps.

 

Binzd,

It's the 3.0 V6. I don't think you could get a 4 cylinder 4WD until the 08 model year, IIRC.

I meant the just the plugs. I just did plugs/wires on my '95 Saturn SC2 coupe work beater, so I had that on the brain. Derp.

The prior throttle body I had was the OEM and it tested bad. I had severely jerky acceleration issues, which was a classic sign of failure for the TPS.

The CEL is now off and the acceleration is smooth now that I've replaced the throttle body.

I've ran a can of Seafoam through it last week, and it still doesn't seem any better. I think I might have to bite the bullet and put new plugs in, since that seems to be the only culprit remaining for the poor fuel mileage issue.

I'm going to take it back the dealership I bought it from and see what fluid they used for the transmission. Since it's a Dodge dealership, I have a sneaking suspicion that they may just used generic transmission fluid... could that be part of the problem maybehaps?

 

Damn, that's terrible. I drive mostly highway and my fuel computer usually always climbs up to 24-25mpg and stays there. Your only about 800ft above sea level in minneapolis which is about the same as mine, so yea, something is definitely up with your car.

Perhaps the dealer put in the cheapest plugs they could find, instead of NGK ILKR7B8 which are the oem plugs.

 

gggplaya, I'm starting to wonder if they didn't put a super cheap set of plugs in, and the faulty throttle body causing the fuel mixture to run super lean didn't totally toast them.

I'm going to go to O'Reilly's and buy the recommended plugs. I'm almost certain that's what is at the root of my horrid mileage.

 

So what was the result of swapping out the plugs? Was the problem resolved??? I have a 2006 which averages 16mpg. That's simply crap! I had a 1997 BMW e36 that averaged 23.5 mpg with a 6 cylinder! This is only getting 4mpg better than my 89 FORD BRONCO and that had a V8!! The previous owner said they did a tuneup a year ago. I'm wondering who the hell tuned it up. I'm going to swap out some components and see what happens.