I have a 2007 Hyundai Accent SE with a 1.6 liter engine in it. It was stalling often so I hooked up a code reader and it said the MAP sensor was bad. I tried to check it to see if it might just be dirty, and when I pulled the map sensor out it was wet. When I smelled it, the wet part was gas. I can't figure out how gas could get on my MAP sensor. I have a new MAP sensor but i don't want to put it in until I can figure out why gas is on the old one.
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Good technique and a great question! Welcome to the site!– cdunnCommented Apr 18, 2016 at 21:54
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2 Answers
When I looked online, here's what I found about the location of the MAP sensor in your car. As always, a picture is worth a thousand words:
From looking at other info about that car it's port injected, not throttle body injected (individual injectors on each cylinder, not just one on the throttle body). As far as I know there should never be fuel in that throttle body. There is one exception that I've been able to find.
When the car has a fuel pressure regulator mounted near the fuel rail, it generally activated by vacuum pulled potentially from the throttle body. If the diaphragm in that regulator has a small tear in it, that could cause this issue. But, all of the reading I have been able to find says that your car has a return-less system (no return, no diaphragm driven FPR (Fuel Pressure Regulator)) and the pressure regulator is in the tank with the pump.
However, I did find some reference to a fuel injection pressure damper and your car has one of these. These are mounted on the fuel rail, but don't seem to be vacuum operated devices. They simply smooth out the pressure waves that can exist in your fuel delivery system. I may be wrong about that and maybe they are vacuum operated, but nothing I have found says they are.
Bottom line, it seems there is fuel being introduced to the interior of the throttle body, and the most likely cause is a broken barrier that is supposed to keep fuel out of it. Search along the intake path, and see where the fuel starts. Pull the intake hoses from the filter, and see where in the path the wetness from gasoline begins. That should give you a good idea of where the leak is coming from. The path is short, so it should be a short search. You would be looking for something that is connected to both your vacuum and fuel systems.
I hope that helps. At least some.
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The car might also have a bad injector that is spraying more than normal under low RPM and the fuel might get sent up the intake tract. Commented Apr 19, 2016 at 3:52
A small portion of exhaust gas is sent back to the intake to improve emissions via the EGR hose.
If your vehicle is running rich, some fuel will be left unburnt in the exhaust gases. This can explain the wet fuel that you are seeing on the MAP sensor.
Unfortunately, this is an indication of bigger engine operability problems. It doesn't surprise me that you're suffering from drivability problems as a consequence. You may want to have the fuel trims inspected. If you share the data on this site we would be happy to help you troubleshoot the problem as well.
