Skip the auto shop - Our mechanics make house calls

Q: 1999 Mitsubishi Eclipse running rich and stalling at idle

asked by on

I have a 1999 Mitsubishi Eclipse. It's running rich and stalls occasionally at idle. I've done a fuel pressure test and it looked fine, which I believe can rule out a leak in the injector. There is no MAF sensor and the throttle position sensor is reading 13% at idle. What is my next step?

A: First of all, you’ve got to realize that, a...

First of all, you’ve got to realize that, although those technically don’t have a MAF mass air flow sensor, those use what is called a Karman vortex sensor. Those sensors are notorious for going bad on Mitsubishis.

They do the same thing--they measure how much air is going into the engine to tell the computer how much fuel is going to put into a fuel injector. You will want a certified technician, such as one from YourMechanic, to come and hook up a high-level scan tool and analyze the Karman vortex sensor.

That can easily be what the problem is. If it is not that, running rich either means that you are getting way too much fuel, or you are not getting enough air. So, you’d want to check and see if you have any air restriction on the intake.

Something as pesky as an air clogged air filter can do that. You can also have a problem with the fuel filter. You might check it, to see if the fuel filter is clogged or anything like that. But, your throttle position sensor is reading 13% at idle. That is actually a little bit high. If it’s saying that it’s a little more open than it is, then the computer will send more fuel to the car and that will make it run rich. That a lot of times can cause that problem too. That’s a relatively common thing that happens to those cars. I recommend getting the car checked and having a qualified technician diagnose your stalling issue. That way, you can be more certain about what repair is needed.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Ignition fuse keeps blowing

You had a good start by tracing the wires and making sure they were clean, dry, and not damaged. To make sure you covered the entire circuit, I recommend you use an official wiring diagram to check this. It is...

Q: Can dirty filters cause the truck not to get enough power to pick up speed?

Hi and thanks for contacting YourMechanic. Dirty oil can cause problems with the engine, but not in two weeks unless you are driving long distances on the highways. Adding oil will actually aid the oil, so no worries until you...

Q: What causes a howling sound in a 99 Buick Regal LS?

Hello, thanks for writing in. The howling noise may be an air filter housing or the filter problem. Try to remove the air filter after cleaning out the filter housing and securing it and road test to see if noise...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...