Hi everyone, I just purchased a 2013 Mitsubishi Outlander Sport from CarMax and I have noticed what I believe to be a serious issue. I have a 30 day warranty but CarMax is telling me nothing is wrong. I will explain.
The vehicle has only 32k miles on it and the engine looks like it's never even been run before. The rated mpg is 24/31 City/Highway.
Even if I drive like a grandma I'm only getting 13mpg. The exhaust smells like sulfur at idle, at a cold start and after driving for 30 minutes. While driving, often the entire vehicle fills with a sulfur smell, and it is especially worse when accelerating. The vehicle has practically no power or acceleration, but it's especially worse when taking off from a complete stop. If I remove the oil filler cap while the engine is at idle no oil sprays out but there is A LOT of air coming out very hard, I mean some serious pressure. The engine feels like it is vibrating a lot and is loud... Definitely does not sound or run like it looks and not like an engine with only 32k miles on it. I checked the service history and it has been serviced at all of the recommended intervals. It was never a rental/fleet vehicle nor have any accidents been reported.
What could this be? Of course CarMax is going to tell me nothing is wrong because they don't want to lose any of their profit from having to fix a vehicle they've already sold. I have a lot of bad experience with car manufacturers and their worthless warranties where they never fix anything so I don't have much faith in Mitsubishi honoring the remainder of the second owner warranty because they are likely just going to say that the previous owner did some magical thing to void the warranty.
So I'm going to try to fix this thing myself since I didn't notice the issues until after the 5 day return period that CarMax offers. When I complained about the lack of power and the vibration they simply told me that the computer needed 100 miles to adjust the performance because they had replaced the battery. Unfortunately it took 6 days before I made it far enough past 100 miles to realize that the computer did not fix anything.
Please help

 

You have a major catalytic converter blockage

That's the sulfur smell. Cat's use precious metals that change the chemical composition of the exhaust at high temperatures. You are not getting the correct reaction either due to a bad cat OR there can be a major exhaust blockage elsewhere

That computer line they gave you is BS- it only learns how much fuel to add and since you are having to gun it a lot, then you are making the cat situation worse

I disconnect my battery all the time. I just end up peeling the tires a lot until it learns my driving style on takeoffs from a stoplight.

The vibration and everything you said sounds like a major exhaust issue, anywhere from a cracked header to someone shoving a banana in the tail pipe. Back pressure can mess things up bad, fortunately, if caught soon enough there is normally not permanent damage (except for a catalytic converter constantly soaked in fuel, that is not so forgiving)

Cheers and good luck

 

i agree it could be many things simple and difficult.

check:
1. gas cap sealed completely
2. bad gas canister
3. fuel filter
4. catalytic converter clogged
5. fuel injector or rings

some mechanics suggest for a catalytic converter to use lacquer thinner and run it for 60 or more miles straight. or run the tank all the way thru.

also did you do a tune up?

 

I had a similar situation with the smell, acceleration and gas millage on a Dodge Grand Caravan and it was the Cat. It had crumbled and lodged into the exhaust pipe. I had taken off the cat and dislodged the clog and cleaned out the cat. I had reattached the cat and everything improved. Ordered a new cat and installed it with a new O2 sensor. Situation resolved.

As far as the air pressure coming out of the oil cap. That is pretty normal since air pressure will be created from the crankcase and all the moving parts. If the air blowing out smells like fuel, or is has a loud hiss, then it may be possible that the vehicle has worn out the piston rings, and is experiencing what is called combustion blow by.

When I Googled the term this is what returned:
The term blow-by , means that the fuel air mixture blows past the piston , and into the crankcase. The system used to control and correct this problem , is called a PCV system - Crankcase ventilation system.

There are some ceramic oil additives that claim to fix this problem. Perhaps something to look into if the problem is significant enough.

 

I was just working on my friends car and thought of the simplest thing that could also explain the symptoms. A clogged air filter starves the engine of air and leaves you running a rich condition, which after a long time begins to damage the catalytic converter and gives you really bad gas mileage.

Just an easy fix thing to check out