Hey guys i need your help because this is going to drive me nuts. I have a 2004 dodge neon sxt that i bought in july ever since i bought the car the car has been having issues. The 1st issues that i'm mainly concerned about is when its warm outside and I'm at a stoplight or stop sign, the car would start vibrating when it gets to around 500 rpms. The 2nd issues is when i try to start my car up on warm start when i had drove for a good while and then after around 20-30 min when i start it up it doesn't start up all the way. my car has seen so many firestones and even the dealer. The dealer told me that i should "put up with it". i refuse to believe that i should just put up with the issues. I'm starting to believe maybe it could be the IACV but the dealer is thinking that it could be a mount on the car that is not right. i love my neon but this is just driving my crazy.

Any advice?????

 

A lot of people with a neon has the "Rough idle" issue. However, i have never heard anyone say its only when its warm outside. For me (and my brothers Neon) they rough idled and lowered RPM at any temperature outside but was always really bad when you had the heat or AC turned on (added load to engine). I did some digging and found out that Chryslers programming for controlling idle (how much the throttle plate opens for air to enter) was off and not allowing it to open enough.

Try pressing the accelerator in A LITTLE, just enough to depress it. If it doesn't do anything to help, give it a little more. If it does help that is probably the issue. What also makes the situation worse is the throttle body gets gummed up with grime and causes the throttle plate to stick. Thus making it hard for the car to idle.

What I did for my 2000 Neon with 191k miles and my brothers 2001 Neon with 125k miles is simple. I removed the air box cover, pulled out the air filter (threw it out and replaced), unbolted the throttle body from the air box (4 bolts), removed air box completely, unbolted the hose clamp on the rear of the throttle body and pulled it out so i could get to it. You don't have to remove the accelerator cable and/or cruise control cable but you can it will make it easier. I used TB cleaner (make sure its safe for sensors) and sprayed the heck out of it while using a rag to clean it. Make sure you open and close the throttle plate as your doing it. I also sprayed some into the intake manifold portion and used a rag there as well. I let the car air dry for 30 minutes before putting it back together.

I also added some fuel injector cleaner to the gas tank twice, it was a whole $8 and the filter was about $15. That $23 and 1 hour of my time job solved our issue by 97%. it barely shakes while idling. More than most cars, but far better than it feeling like its going to jump out of the engine bay.

Try that first; It's cheap, easy, and you'll learn your way around the engine. With that said it could still be a mount, IACV, bad fuel injector, bad ignition (plug or wire), or in our Neons case oil in the spark plug tubes (mine was so bad after it sat for 5 days i couldn't start the car lol).

Checking the upper engine mount is easy. Its on the passanger side, it's a large silver part with black rubber in the center. If the rubber is cracked, missing, or pulling from the silver it should be replaced. Try yanking on it and if it moves a lot if should be replaced. It should be fairly firm. The part is around $25 and easy to unbolt and fix. The other mount is almost directly below it, you have to lay on the ground and look for it. It's over a foot long and the same thing applies to if its bad. That one is a little bit more of a pain to remove but easy enough. The other two mounts are far more involved, worry about them later.

Start with the easy cleaning, fuel injector cleaner and air filter and see what that does. If it doesn't help, check your mounts and replace if needed.

What do you mean it doesn't start up all the way?

Oh, dealer suck. I went to pick up some transmission coolant lines and they complained that I was having them put in the order. $25 order, they said i should junk the car. Can't be hatin the Neon

 

Thanks Steve for the information. I'm going to try the things you suggested. Actually when i make a complete stop i actually would press on the accelerator for the car to stop the low idling and vibration. sometimes what i would do is turn on the a/c for the idling issue to stop but unfortunately right now its below 20 where I'm at lol

i do want to report today i did a little testing and when i unhooked the IACV at first the car would not start up but after pressing on the accelerator, the car would start up without the IACV even it would still idle low when at stop light but it would be more noticeable. I'm starting to lean towards something is definitely going on with the IACV.

I checked out the top mount and when i looked at it the rubber part looked cracked. I even checked the bottom one that on the passenger side as well and the rubber looked cracked as well. So most likely the mounts was not replaced even the dealer told me it was.

What i meant when i say the car doesn't start up all the way is when i start my car, my car should start immediately. on a warm start after letting the car cool for around 20-30 min the car would take around 5-10 seconds to start up.

 

Not sure if this pertains to your starting issues tech, but the 01-05 Neons had the 1st generations key sensors. Fun little things that take a low wavelength sensor from the cars cpu and tells it that the key your using is the correct one. I have done a small amount of research and found that some neons have a feedback delay in that cpu which causes the first turn of the key to do nothing but crank the engine, a longer or 2nd start is sometimes needed. Not good when trying to make a quick getaway, but 2 starting the car can help. My 02 does it and you do "get used to it" as the dealer told you.

 

as far as it taking a little bit longer for it to crank, if that a normal thing then that something i could live with but what annoys me is the idling issue/vibration, the dealer told me i would have to to live with the idling issue/vibration. One thing is when the car does finally start, sometimes the car would idle low and the check engine light would come on, then when i press on the accelerator a bit then it idles back to normal.

 

That's something I didn't know. I wonder if my brothers 01 has it. Probably does if you say the 01-05 Neons do. I know my 04 Ranger has the key sensor security, it takes a few moments to start sometimes maybe that's the issue with that.

Anyways, to your issues; Gad is probably right about why it takes a few moments for it to turn over. I neglected to mention how to check for oil in the spark plug wells; just pull a boot out and see if its covered in oil. It's probably not a big issue but its easy to look for it. Cheap and easy is always best to start with none of us are rich

I highly doubt the mounts have been replaced. Most people just let the Neon run til they have issues with it then sell it off to someone, usually guys like us. Try putting your palm on the ignition coil (engine off) and rock the engine. If it moves you have a mount issue, I'm sure however you have multiple issues that contribute to the engine idle/vibration.

Now i know you can start the engine without the IACV, that's neat Hmm, last i checked that was at least $60 for a aftermarket part. I'd put that off until you clean the TB and replace the air filter. if your car has over 75k miles it's a good idea to do that anyways. Get the maintenance out of the way. If it still doesn't help I'd change the spark plugs. $2-3 each, easy to do, and should be done about 100k miles anyways. Wires could be bad but I'd only replace them if they have visible damage (or in my case if things look like @h#*t it bothers me and i replace them).

With all of that cheap and easy (also important) maintenance out of the way now you KNOW its been done and isn't the problem. At that point I'd double check those mounts by pulling/pushing on the ignition coil to see if the engine moves, it really shouldn't move a lot and it should be difficult to do. On my brothers 01 i crawled under the engine and pulled on the lower mount and it moved 1-1/4 inches side to side fairly easily...So NOT good. I changed that and most of his idle roughness went away. The top is the same logic too.

Those mounts are $25 or so each. They are probably worn out after 75k miles anyways. Order all your stuff from Advance auto ONLINE if you are near one, use the promo codes to save a minimum of 20%, I bundle stuff and save 40% all the time.

With all that basic maintenance you have spent about $75 before any discounts and its out of the way for a minimum of 50k miles. Now is when I'd try the "Key Jingle" for the Neon to get the code that its throwing. Or use a scanner. I bought a $20 off Amazon and its served me well. At this point I'd look into replacing the IACV. IT could even be oxy sensor, crank or cam sensor...but it depends on the code you get. So many possibilities its sickening, thats why i say do the easy, cheap and important maintenance first. Unless of course you know for a fact it was all just done (but It's a Neon i doubt it).


I never "live with it" I pick at the problem until i fix it otherwise I go mad.

 

I agree, i can not just live with the problem because i'm going to try to find some type of fix if the issue is not tolerable.

My car has 125k so some maintenance could do some good, even though a place called firestone and the dodge say they already did maintenance but it seems like i got to take things in my own hands. I did what you said, i pushed and pulled on the ignition coil and the engine didn't move all and i was putting some muscle into it lol. My spark plug wires does looks brand new but im going to check my spark and do maintenance on the TB friday on my day off. The cam sensor was already replaced in the car.

Actually at my job we have this discount site we can go on and advanced auto is on that list so I'm going to start shopping for parts.

 

My 2004 Dodge Neon all of a sudden started vibrating really loud when in gear and while driving. It doesn't vibrate bad when in Neutral or Park. The top and bottom motor mounts have been replaced but the middle one has not. The rubber inside the middle one is cracked but still there. But .... that has been like that. What is it? HELP!