Hi, I'm new here, but hoping that I could find some help. I have some basic car knowledge, but don't do any work on them myself, nor would I start now! I'm mostly needing some help diagnosing this problem so that I can have a starting place to discuss it with a mechanic.

I have a 99 Neon DOHC with 128,000 miles. I've been having some engine issues of some sort. There isa rough shift between 1st and 2nd gears (automatic) and sometimes when I'm maintaining a steady speed (45-50mph), the engine sort of hesitates, like a hiccup or something. There is a slight jerk but everything keeps going. This has been fairly constant since I got the car. More recently (2 months?) every once in awhile this is accompanied by a squeak. Also, when I idle in gear (at stoplights), there is sometimes a rough vibration noise in the engine. The whole car doesn't shake or vibrate, but I hear it in the engine.

I think I might have a slight dip in gas mileage, but its not consistent, so it could be unrelated. Car does seem to lack power sometimes, like its just sluggish.

Sometimes when I'm slowing down to come to a stop, the engine does not downshift smoothly and there is kind of a "clunk" that is more felt than heard. Does that make any sense?

I don't have any check engine lights on, but I'm trying to avoid a major problem of being stranded somewhere at some point. My initial thought was a transmission problem, but I'm not sure this is the issue. I had the timing belt replaced at 105,000 miles when I bought the car as a precaution, but I'm wondering if it was maybe not adjusted correctly? I had a transmission flush 3 weeks ago and it had no effect on the problems. I do get regular oil changes. I'm considering just going ahead and getting the spark plugs replaces since I don't know when they were last changed.

Any advice or insight on these problems would be great! Are they related problems, multiple problems?

 

First of all, WELCOME!!!!

I'd start with the spark plugs first. Get some regular stock copper Champion plugs.

 

Well, the spark plugs and wires have now been replaced. The mechanic said that I did have engine misfire codes in the computer, even though my check engine light was not on. I've noticed an increase in power, its too soon to tell about the gas mileage though. The rough idling is pretty much gone - when its cold, it will go in and out of a rough idle, but its not like before.

I do however still have a bit of a "hiccup" when driving at a constant speed and I do occasionally hear a squeak when accelerating. I have not experienced the downshifting problem again yet - but its only been 2 days. Any thoughts on what could be the problem still?

 

loose belt

 

the mechanic said u have a misfire code even though ur check engine light isnt on ??..that doesnt sound legit to me...ask him if you can watch him clear the codes ..and if its true ..id start by checking the connections to the injectors...if the connections are good try cleaning them ....if that dont work sry but ull have to break out the check book and buy new ones...im not sure because ive never bought stock ones ..but the are probably somewhere are 70-80 dollars a piece....see if you have a certain cylinder misfiring ..itll be like " cylinder 1 misfire " on the scan tool ...hope this helps you some

 

So the squeak could be a loose belt - any idea which one?Don't know that you could diagnose that over the internet.

I'm going to keep driving it for a few days to get a better description of what it is still doing, but I'll keep in mind the injectors - I'm sure you mean fuel injectors? Will the additive stuff that you put in the gas tank help that? I've not really ever done that because I wasn't sure if it was good for the car.

 

First off, I have seen people go to the trouble of disconnecting the light or removing the light for the CEL indicator. If the car had issues before you bought it, the past owner might have disconnected it so it would sell.

An easy way to check which belt might be the culpret, leave the car in park and turn the steering wheel hard left and hold it, then go all the way hard right and hold it for a few seconds. If you hear a sqeak or sqeal, then it is most likely the belt with the power steering pump. If you don't hear a sqeak, then it is most likely the belt with the alternator. I know on my '95 Highline, even after I thought the belts were tight, they occasionaly made noise at random times.

Hope that helps...

 

I had a Dakota that behaved in a similar way, in terms of shifting. It turned out to be the torque conveter, it would not lock and unlock properly. I don't know if the 1st gen Neon had a lockup converter, but the second gen Neon's do. The problem traced back to the throttle position sensor sending conflicting information to the PCM, so it would lock and unlock the converter randomly. Hope this helps.

 

Okay, well I haven't taken it back in and the squeak seems to have gone away, so maybe it was just a random belt issue.

I'm now having a thought that I might have an alternator problem. Today my battery went dead randomly - I just replaced it at the end of December (07) when it also went dead with no warning. I can't recall having left a door open or doing any unusual things that would drain the battery so quickly, so while searching on the internet, I began to suspect the alternator. I found a page that listed alternator failure symptoms as

"At 105,000 miles Paul's RR began experiencing idle instability and even stalling, as well as a ghostly little misfire which was anywhere from just a slight hint of a stumble to a complete cut-out. The misfire problem was usually associated with steady light throttle at highway speeds -- and especially at night when running with the headlights on. " http://www.rangerovers.net/repairdetails/altrebuild.htm

Now, this was a Range Rover, but I'm wondering if this could be the problem? I also had a friend install a new stereo system last fall and I'm wondering if that could be a problem that is just draining the battery. I think I recall checking the power usage of the unit, but maybe I didn't.

Any thoughts on my alternator as a problem? Cana place such as Autozone diagnose an alternator problem?

Thanks for all the help!

 

Autozone can test the alternator for you. Just take it in.