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Old 06-15-2007, 10:18 AM
Mh488 Mh488 is offline
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Dodge Neon rough idle

I am driving a cheap car for fuel economy reasons. The 2000 Dodge neon I got for $3800 with 36K has been a great car. At 87K, I just had the timing belt, water pump, thermostat, spark plugs replaced. The car has an intermitent rough idle issue. It shakes the steering wheel and causes rattles at stop lights. I thought the timing belt/tuneup would solve the issue but it hasn't. The car runs great, still getting very good gas mileage. Could it be O2 sensors? Fuel pump? Spark plug wires? A sensor? Any help at all would be appreciated. I can do minor repairs myself, to save money.
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Old 06-15-2007, 11:08 AM
dougbfresh dougbfresh is offline
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Is the Check Engine light on?
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Old 06-15-2007, 11:24 AM
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Carboned up throttle plate, vacuum leak, dirty injectors, stuck EGR valve? Could be a lot of things.
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Old 06-15-2007, 11:49 AM
Mh488 Mh488 is offline
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Thanks for the responses, no check engine light. I asked someone at work and they told me to trade it in on a Honda or Toyota, I don't want any car payments. I will check the egr, vaccuum hoses and maybe schedule a intake cleanup. I ran a can of BG 44K a while back didn't seem to help.



Two kids and a wife...someday I will have my old musclecar...someday.

Last edited by Mh488; 06-15-2007 at 11:51 AM.
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Old 06-15-2007, 03:17 PM
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It wouldn't hurt to see if you have a vacuum leak around your throttle body or intake manifold. Sometimes you can find a leak using some starting fluid and spraying around the base while the engine is running, if the idle changes, then you found a leaking spot.
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Old 06-16-2007, 01:08 PM
Mh488 Mh488 is offline
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Thanks for the info everyone. I looked at the intake, looks like plastic, cars are cheaply made today. I will try the starter fluid check, didn't see any loose or cracked hoses, not much to see on a Neon. The car has a cheap cold air intake( used cars), so I replaced the filter with a K&N filter, maybe that will help. I'll post back when I solve this issue. Any info is greatly appreciated, I intend to drive this till the connecting rods or bearings fail...go Mobil 1 oil!


99 Jeep Cherokee 4.0L 125K (just broke in)
00 Dodge Neon 31-36mpg (70miles per day)
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Old 06-16-2007, 03:05 PM
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Plastic intakes are known to have leaks. I know gm had a lot of trouble with plastic intakes leaking over the years. And now are back to a metal. So it wouldn't surprise my if you have a leaky intake or not.
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Old 08-21-2011, 03:21 PM
phagan89 phagan89 is offline
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i am having a similar problem with my 00 neon. it idles rought with the a/c on and in gear. the idle drops down to about 600 rpm but with the a/c off it idles smooth in P,R,N and D but turn on the a/c and the idle drops and gets very rough, any thoughs?

i just finished putting the car back together after doing a head gasket. replaced all mounts, timing belt, water pump, fuel pump, cleand fuel tank, lines, fuel rail, injectors, new air filter and all that jazz that you would think to do while you had the motor out.

i am also only getting about 16mpg? but that may be unrelated to the idling problem?

thanks
Patrick
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Old 08-22-2011, 01:56 AM
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Bad idle neon

tHE FIRST THING TO CHECK IS ALL YOUR VACUUM LINES. THERE ARE A FEW THAT ARE HARD PLASTIC AND ARE KNOWN TO CRACK VERY EASY. ALSO CHECK THE HOSE BETWEEN THE AIR FILTER AND THE THROTTLE BODY IF AIR LEAKS IN BEFORE THE "MAF" ITS NOT A PROBLEM, BUT IF AIR LEAKS IN BETWEEN THE "MAF" AND THE THROTTLE BODY YOU WILL HAVE BAD PERFORMANCE, GAS MILEAGE AND IDLE
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Old 08-22-2011, 02:28 AM
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Hey 54, can you please lighten up on the CAP'S please? It's almost blinding. Please use lowercase if ya will and welcome to the forum.
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Old 08-22-2011, 05:10 AM
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I don't know specifically about the Neon but there is sometimes a throttle advance solenoid that gets 'tripped' when the A/C gets turned on (this helps to raise the idle enough to maintain smooth operation when the load of the compressor is engaged).
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Old 08-22-2011, 10:13 PM
phagan89 phagan89 is offline
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thanks for hints guys. i'll double check the vacuume lines and check out the a/c switch thing cause that makes sense.
thanks!
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Old 09-22-2011, 05:18 PM
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I had/have this problem

I'm posting here because this is the first thing that a google search brings up when I search for this problem.

My '97 Neon has been idling very roughly for a while now. Today it got to the point where it would stall if I didn't give it gas. It turned out that the problem was the idle control valve. in the throttle. On my vehicle the throttle is located at the front, driver-side of the engine. Removing it required removing the air hose, three bolts, a vacuum line and two quick-connect electrical connectors (one of which controls the idle valve). The valve is attached to the electrical connector that is not inline with the main butterfly throttle valve, it comes out easily after removing two bolts.

IF YOU CAN'T GET A REPLACEMENT AND NEED YOUR VEHICLE: I was able to get things "working" again by placing the throttle valve in a specific position and leaving it disconnected. It's on a screw so you can adjust it by turning it. You'll strip the top part of the plastic cylinder in doing so, but if the thing's already shot then it shouldn't matter.

The position of the thing was touchy, it took me quite a few tries to get it. If you look in the bottom of the idle with the valve inside then you'll see the valve. At the top of the valve is a bullet-shaped piece. It seems to work well enough at about four mm from the fully-closed position. I had to remove and reinstall the throttle quite a few times to get it, I found that running with just the two bolts and the vacuum line was good enough to test the idle. The end result is that the idle is now always too slow or too fast, but it's close enough for now. It should at least get me to the wreckers to find a real replacment.

It's not the best solution, but any port in a storm, eh?

I hope this is helpful to someone.
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  #14  
Old 09-23-2011, 08:54 AM
dougbfresh dougbfresh is offline
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The best advice for a Neon owner is to LEAVE it at the wrecker when you go there.
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