Engine not working right, need good help

[eugenesxyby999]

hi,


I have a 1997 mitsubishi eclipse rs. Im getting some engine noises. The rpm doesnt stay constant when its in nuetral. It moves to 1 and then back to 1/2. The engine is quiet for a second and then it starts to shake and this goes into a pattern. The arrow keeps moving up and down between these 2 numbers and after a couple of minutes, the car just shuts off. If I only touch the gas a little bit and hold it, the car doesnt do this but when I let go off the gas pedal, it does this whole pattern and automatically shuts off.
Also if I dont press the gas and turn the steerling wheel, it shuts off automatically.


Please can someone tell me what to do? maybe something to adjust? Here is the type of motor it has.

click on the picture to make it bigger.
http://img217.imageshack.us/my.php?image=img1511xi0.jpg

 

[Locke]

Begin by removing and testing the IAC. If it test's OK, clean it's pintle and the air bypass galley. Clean the TB too, while you're at it. Check for vacuum leaks around the TB, MAP hole, injector bosses, and the IM gasket area.

If that doesn't fix the problem, test that the TPS is within specs, and check the PS pressure switch.

Keep us updated.

 

[eugenesxyby999]

Locke, this is my first DSM and I really dont have a clue to what you just said. Can you explain in a more easier way?
Can you imagine when I turn the steering wheel, the rpm drops down and the car just shuts off.

Also, when I jump start the car(because the battery is dead), and later on when I turn it off and try to start it again, I get nothing. What can be the problem there?

 

[Black91TSiAWD]

Hows the alternator?

 

[pwayzjellyroll]

Hows the alternator?

x2 Also, if you have to start the car every time with jumper cables or a battery pack and the alternator is fine. Your battery may be shot. I believe they can test the battery at autozone. But I'm not sure as there isn't one really close by me.

 

[Locke]

Locke, this is my first DSM and I really dont have a clue to what you just said. Can you explain in a more easier way?

Here is a full explanation.

The IAC is the Idle Air Control. It contains a stepper motor, which operates like a linear actuator, and a pintle. The pintle sits in a passage that by-passes air around the throttle plate when it shifts in or out, like a valve. The idle on 2gnt's is unadjustable, and controlled solely by the ECU. When an accessory load is placed on the motor, the ECU will open the IAC a little to compensate, which keeps a smooth idle. The PS system can place a pretty large load on the motor. The ECU compensates for the load by opening the IAC a bit. The ECU also compensates for A/C usage, and when an automatic tranny is placed in gear.

The IAC is located on the bottom of the throttle body, (TB) kinda hanging off to the right of the TB. (or the rear, as facing the motor) It is held in place with two screws, and has a four pin connector. The sensor and connector directly above it would be the Throttle Position Sensor. (TPS). With the TB removed, you will see a hole in the front bottom of the TB bore before the throttle plate. This is the opening of the air bypass galley. On the back of the TB, you will see a smaller hole beneath the big TB bore, this is the other side of it in the TB. This hole continues into the Intake Manifold (IM), then turns up, leading into the plenum.

To test the IAC, use an ohmmeter to check the resistance between pins 1 & 4 (the two on either edge) on it's connector, and pins 2 & 3 (the two in the middle). You should measure 38-52 ohms. If resistance falls outside this range, replace it. If resistance is within this range, clean it.

To clean it, remove it from the TB. You will probably have to remove the TB to do this. Take some carburetor cleaner and something like a soft bristled tooth brush, and remove as much of that black crap inside the IAC as you can. The funny, rounded thimble looking thing on the end of the IAC, that goes into the TB, is the pintle. Clean everything you can, but avoid getting carb cleaner near the connector. Use the carb cleaner and a Q-tip, or preferably a pipe cleaner, to clean out the air bypass galley as well as you can.

Reassemble and take it for a test drive.

Can you imagine when I turn the steering wheel, the rpm drops down and the car just shuts off.

If the IAC is sticking, or part of the motor is damaged, the ECU won't be able to adjust airflow to make up for the added load of the PS system. If the PS pressure switch is damaged, the engine may have a bad idle during use, or die. Should probably have a shop diagnose this, unless you want to just replace it.

Also, when I jump start the car(because the battery is dead), and later on when I turn it off and try to start it again, I get nothing. What can be the problem there?

I would first start by having he battery placed on a load pile. (since it is the easiest to remove and replace) Most auto parts stores will test your battery for free if you don't have a load pile. After that check the alternator. You can simply check the voltage it outputs, which should remain pretty steady at between 13.5-14.5, or just remove it and have it tested at an auto parts store. If those test both good, then we can begin looking for other causes.

Most of this can be had by searching our 420a forums, BTW. Good luck, and I hope this helps you.

 

[eugenesxyby999]

thanks locke for the very detailed reply. I will try to go to a shop and let the diagnos it.

Black91TSiAWD, im thinking that the alternator isnt good either. This car hasnt been turned in about maybe 2-3 months so Im guessing it got bad.

pwayzjellyroll, I agree with what you said about the battery. After I take the connector cables off and let the car run for a good 10-15minutes. Im not able to turn the car on at all. The lights stay on for a few seconds and its gone. So I will check that out. Thanks.




Any more suggestions? Maybe something I can do manually with the car?