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Question

2000 Dodge neon turns off while stopped

Jul 19, 2017 8:46AM PDT

Hello forum members!
I have a 2000 Dodge Neon with a 2.0 liter engine/ 16 valves and manual transmission. The problem started about two months ago when it simply turned off with no prior notice (no jerking etc.) while at a stop light. I am able to turn it on as soon as it turns off and it turns on just fine with no problem whatsoever. When it does turn off (it happens maybe twice a week at seemingly random times) I did notice the last few times that the idling was just a bit rough, nothing too significant and that right before turning off the rpms would start dropping until it shuts off. This has happened with the clutch disengaged and the gear on neutral. Dont know if its my imagination but I think that if I rev the car up a bit while in neutral it keeps the car from shutting off whenever I "sense" that it's about to turn off. I had the crankshaft sensor replaced about a year ago and that's about it. Got the spark plugs changed too but this was about 3 months ago. Im not too savvy with car tech problems but i get the feeling that this may be a problem with some sort of a sensor or fuse or something electrical. My gas mileage with the car hasnt changed and my car drives fine other than that. This problem has never happened while driving. Got the car scanned and no codes came up either. This only seems to happen when my car is at normal temperatures (not when its cold) and it doesnt overheat. Any thoughts on this? Any help on the matter would be greatly appreciated. Thanks a bunch!

Discussion is locked

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Answer
Long shot.
Jul 19, 2017 9:37AM PDT

I happened to be listening to the car guys on NPR and this issue on another model came up. The best guess they had was a diaphragm in the carburetor. Example search.
https://www.google.com/search?q=carberauter&ie=utf-8&oe=utf-8#q=carburetor+diagram+stalling

Let me be clear, same symptoms of stalling, rough idle and sometimes turning on the AC can cause it to get by.

Hope this helps.

PS. https://www.google.com/search?q=2000+Dodge+neon&ie=utf-8&oe=utf-8#q=2000+dodge+neon+idles+rough finds you're not the first to notice this issue/problem.

Post was last edited on July 19, 2017 9:59 AM PDT

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Rough idle
Jul 19, 2017 10:29AM PDT

I'll definitely take a look at that, I don't have a major major rough idling problem but I did notice a slight roughness to it after this whole thing started. Thanks again!

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Answer
Neon
Jul 19, 2017 9:41AM PDT

Hi; From the symptoms you listed, it sounds like it could be as simple as a dirty/sticky IAC (idle air control) motor. 99% of the time, you can take it off and clean it with carburetor cleaner, and it will be fine. Once in a while, we'll have to replace one, but.... When the engine is cold, the computer commands more fuel (rich) since there is no choke with fuel injection. That's why it doesn't die when cold. If you have never had an injection service done, I'd highly recommend it. Call around for estimates, but make sure they use a MotorVac fuel injection cleaner. Also, make sure they will clean the IAC and throttle body also. Normal cost in our area is around $100.00. You'll notice an improvement in performance and fuel economy.
Loren

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IAC valve
Jul 19, 2017 10:25AM PDT

Thanks for the reply landchamp,
I cleaned out the IAC valve about a week ago with carb cleaner and it didn't seem to be too bad BUT I don't recall it ever being changed whilst owning the car (going on 4 years now) So it could be that it hasn't been replaced for an even longer period of time. What would be the recommended time frame on getting those replaced? As for the throttle body I did that as well, only thing that hasn't been done in about a year and a half-2 years is the injection service. I drive an average of 200 miles a week so I don't know if it'd be recommended that I get that done again. Thanks again!

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Neon
Jul 21, 2017 12:50PM PDT

Hi; Still sounds like an IAC problem. When you turn the A/C on, the IAC kicks up the idle speed to compensate for the drain of power (compressor engaging). If you drive 200 miles a week=11,000 miles a year. No, the fuel injection system shouldn't need it already. (assuming it was done correctly last time).
A scanner will show upstream O2 operation. .1v is lean, .9v is rich. Should be cycling up/down constantly. If it stays at any value, it isn't operating correctly. However, there can be contributing factors causing the poor reading. Good luck. Hope you get to the bottom of this. Remember, the downstream O2 won't affect the way the engine runs. It tells you if the cat is doing it's job. I don't replace parts until proven faulty. You can also monitor MAP/BARO, command IAC, ect. with a scanner. Although I suspect a faulty IAC, don't replace it until you can prove it's bad.
Loren

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Answer
common cause
Jul 19, 2017 10:09AM PDT

is the exhaust fuel mixture control located on the manifold, or top of the pipe attached to it. It's often called Oxygen Sensor or O2 sensor. Another sensor usually not to difficult to check on a car is the MAP or manifold absolute pressure sensor, sometimes called the mass air flow sensor. It affects the timing too and will let idle keep dropping. You can test most of them simply by unplugging it and see if the idle increases when warm and stops idling down. However don't drive it fast since it can run the timing way up and then you get back kick from the engine.

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Testing sensors
Jul 19, 2017 10:18AM PDT

Hi James, thanks for the reply.
Ok, gotcha, just have a question though; when testing by unplugging them I'd have to be driving the car or would I also get the same results with the car being stationary? And what I would I be looking for to identify a possibly faulty sensor? For the car to idle up and and then to idle down? Thanks again!

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for the MAP, you unplug it
Jul 19, 2017 10:37AM PDT

then crank it, and drive it around a bit without speeding up fast (that kicks the timing too quick too high). Best to do when it's already warmed up since that's when you have the problem. For the other one (don't test both at same time) if you unplug it, the system runs too rich, but it won't "lean out" on the air/fuel mixture at least. The danger there is it can cause catalytic convertor to get hotter than normal, so don't want to drive it like that too long. It's then in "limp in" mode as some call it. It will run OK, but the gas mixture becoming richer will drop your MPG by a few miles.