420A Car stalling problem

[Valley_DSM]

Hello, so I’ve had my Eclipse for almost a year now and I’ve had this problem where I guess at low rpm’s, the car struggles. For example, once the car is running, it’s fine but when I come to a stop at a light or stop sign, the rpm will drop down to around 500 and start bouncing under 1000 and you can hear the engine struggle and it’s a gamble of whether it ends up turning off or not. There are times where the needle will drop to 0 for like half a second where the car basically turns off but then it shoots back up and I guess saves itself? Another example is when you know how at a stop sign you have to wait when there’s a car in front of you and then they go so you have to tap the gas pedal for you to move forward slightly? My car does NOT like when the pedal is just tapped to inch forward because most of the time, the rpm will just drop to 0 right after and the car will stall. The same applies to reversing when you have to tap the pedal because obviously you don’t want to reverse quickly like for parking. The car will again do the same thing and most of the time stall.

I don’t have any experience working with cars so I don’t really know anything and this also my first car ever. It may have been smarter to get a newer car but I love the eclipse and how it looks so I had to get it. I was hoping maybe someone would be able to at least give an idea on what they think the problem is because I really have no clue.

For reference, I have a ‘97 Mitsubishi Eclipse 2G but just the base model and it’s an automatic transmission. I have also gotten a tune up and have gotten the spark plugs replaced already.

 

[steve]

Is it an RS or a GS?

 

[Valley_DSM]

Is it an RS or a GS?

RS

 

[steve]

I suspected it was a 420A car but wanted confirmation. That will aid others in helping you.

 

[Sirius1995]

Sounds like vacuum issue, spray some brake cleaner around intake manifold where it connects to the engine head and the split part and see if idle gets up for a bit, also inspect all vacuum hoses for cracks or cuts

Is check engine light on? Are you able to read code?

 

[Valley_DSM]

Sounds like vacuum issue, spray some brake cleaner around intake manifold where it connects to the engine head and the split part and see if idle gets up for a bit, also inspect all vacuum hoses for cracks or cuts

Is check engine light on? Are you able to read code?

Yes the check engine IS actually on. I was going to get it checked tomorrow so I’ll reply back with what it says when I do.

 

[BLACK'98DSM]

Hopefully the code scan will provide some insight. If not, here's what I recommend. The throttle body, intake plenum and runners may be restricted due to the EGR & PCV inlet causing build up. The EGR delivers exhaust gasses directly from the #4 exhaust port back into the intake manifold. As you can imagine, these gasses are very hot and will cause carbon to accumulate. Simultaneously the PCV is delivering oil vapors to the intake manifold which will accumulate. The carbon from the EGR will do one hell of a job at causing the oily sludge to stick to the intake walls. Layer after layer it will build up and increasingly restrict the airflow until problems arise. Remove the intake pipe and open the throttle plate to have a look inside. If you see excessive carbon or sludge build up, it is time to clean inside. I've seen massive intake restrictions on the 420a caused by the PCV/EGR combination. Which will cause low idle, stalling and poor acceleration.

My other suspect would have been the IAC valve. But some of your description does not align with those symptoms. An improperly functioning or dead IAC will definitely cause low idle and surging while coasting. But once you open the throttle, the IAC becomes inactive so issues would clear up at that moment. If the engine still tries to stall with throttle open, that's what leads me to believe a restriction of airflow. It could even be something as simple as a clogged air filter or airbox, but that is unlikely unless the vehicle is driven in harsh environments or rarely has the filter replaced. The dirty 420a intake manifolds are far more common.

If this were a fueling issue, you will at least get a code for front O2 reading too rich or too lean. Then we can diagnose the issue within that system. But only if that code is present.