Im just gonna start this thread before hand.

I bought a 2004 Neon SXT (10th VIN # is 4) 143K miles. Car is actually quite nice. Great looking car inside and out. No rust. The problems, i believe, are all easy to fix and probably common, but i need guidance.

1, previous owner was no mechanic. There is no thermostat in the car and it leaks out between the plastic neck and head faster than i can put it in the filler. Heading to junkyard tomorrow to get a couple to cure that

2, Prev owner said it was overheating as to why he replaced the stat (or took it out, as i have found out) and swore he never ran it hot. Motor is quiet as can be, so that part is prob true. i dont believe the fans are coming on. If the temp sensor is bad, will it automatically kick on the fans to hi? If the A/C isnt charged, and the comp doesnt kick on, will it still kick on the fan when i turn on the A/C?
Im getting a stat housing, but what all should i get? There is NO gasket or stat currently on my Neon.

3, From idle, after a minute or two of warm-up, if you punch the throttle to the floor, it will basically just sit at idle and rev up slow enough to make paint drying seem quick. If you feather the throttle, it will rev up fairly quick, and after 2K, you can floor it and it will rev great. Not sure why? Cat clogged? PCV? Fuel Filter? Fuel Pump? Prev owner said it has done that since the day he bought it 3 years ago.

4, I removed the intake manifold and cleaned out all the oil (i read somewhere that this could be from the PCV valve?) there is no oil in the head and the valve area looks pretty clean for 143k miles

5, So far i have put on NEW Champion plugs, Mopar wires, new air filter and cleaned the TB, intake manifold (removed it and cleaned out the puddle of oil), and both sensors on the TB.

Main issue is the stat housing and what i need for that and the hesitation issue from idle. Any and all advice is appreciated



Thanks,
Hunter

 

Welcome back to the 2nd Gen Neon forum.

Scan this puppy for trouble code clues & post up All code Numbers, as they can help focus a trouble shoot. Maybe it could find a clue to shed some light on the delayed rev problem.
If it has a restricted exhaust, like a plugged/melted down cat converter internal matrix, excessive exhaust back pressure can cause overheating & a wimpy go at throttle up.
So, maybe use your vacuum gauge to check the restricted exhaust scenario here. http://www.secondchancegarage.com/public/186.cfm Scroll down to find & play various test scenarios. The restricted exhaust scenario is #14.

So could a fuel delivery problem, so check fuel pressure & delivery flow rate over time, to see if the fuel pump & delivery rate are up to snuff.

I agree the thermostat & gasket should be replaced to get the engine operating temp in the normal range. Check to make sure the radiator cap is good & holding specified pressure & that water pump coolant flow is up to snuff.

Some beginning trouble shooting thoughts for consideration, let us know what you find.

 

Thanks for the reply! i forgot to mention, it has never thrown any codes.

a little update, i put in a fresh stat housing, stat and gasket and filled it up and let it idle for almost an hour and one of the fans only came on once. The highest the temp gauge ever got was a needle width below half way. so, all good there.

Here are some videos of what im working with.

Throttle Issue (this is the best i could get it (new plugs, wires, air filter, and i took off the intake manifold and cleaned it out of all the oil from the bad pcv valve) when its in drive and i floor it, it doesnt even spin in loose gravel and has a super long delay or struggle to rev)

Idle Issue

the lo oil pressure code is a new one and the oil light does stay on when i first start it in the morning, if i run it for about 3 seconds and shut it off and then restart, the light goes out. Oil level is fine, but without testing it with a mechanical gauge, i wont know what the actual pressure is.

 

The top end doesn't sound dry, but the random metallic knock sounds like something is going on in the bottom end of the engine.

Rig a stethoscope from a length of tubing, hose, wooden broom handle, one end on the suspect, the other to your ear & have a listen along the bottom end, from the passenger side timing belt end, to the drivers side, on both the firewall & radiator side of the engine block below the head, then above the head along the cam shaft run & see if you can narrow down where the knock is coming from.

It seemed to me the engine idle began to get rough in time with the knock beginning.
A more experienced Tech could probably tell us what it sounds like right off the bat.

Any idea how many miles on the timing belt?

 

once again, thank you for the great info! and you know, i thought that in the video the knock noise sounded worse than in real life. but idk. you rly cant even hear the thing running with the bonnet closed. and there are 143k miles on it, so i assume its original, if the prev owner was anything to go by, maintenance wasnt a priority and neither was common sense.

another mention is that, after i let it idle for a while (40+minutes) i shut it off and then restarted the engine and the hesitation and idle stumble went away and ran fine for another half an hour after that as well. this morning, the cold start brought with it the idle stumble every 10 seconds or so, just like in the video.

Which brings up another question, in my Jeeps, and other cars, the idle will be slightly increased on startup in cold weather, (i.e. Jeep at 160* idle is 550, when its cold and temp is only 40* outside, idle will be 1000-1050), this car doesnt seem to do that. the idle is always around 850-900. Is the PCM stuck in open loop? is that even possible?

One more question, someone is mentioning that the timing may have jumped, but i read (i think on here) that if the belt is off by even 1 tooth, the check engine light would come on. Is that true? there is no check engine light on when running. and no codes, other than the low oil pressure which goes away after it runs for a few seconds.

 

On the idle question, the engine computer controls idle speed through the throttle body mounted IAC=Idle Air Control. It's an electrical solenoid air bypass valve that receives a varying pulse signal from the computer to open & close the valve to let bypass air around the throttle plate to control rpm as engine load changes. Like when we turn the steering wheel & the power steering pump loads the engine, or when we put the auto tranny in gear, or the AC compressor cycles on, or when we turn on a heavy electrical load, well you get the idea. Anyway, if the throttle plate OD is dirty & sticking open, or the IAC innards are dirty & sticking, it can corrupt the computers effort to control idle speed.
Same kind of scenario with fuel & spark delivery, ect, so what I'm drilling down to is, with the unknown past service history & you believing the previous owner wasn't maintenance minded, suggesting you get All past & present due scheduled maintenance replacement parts up to date with OEM, or parts that say in writing that they meet or exceed Chrysler specs. Like PCV valve, plugs, wires, belts, including the timing belt & it's idler pulley & water pump while your in there doing the timing belt, filters, fluids, like the proper viscosity & service grade engine oil & filter, flush the power steering & tranny, coolant which you say you've done along with the thermostat, radiator cap if not done, O2 sensor, as they usually need changing by 100K miles, then see how it runs & if the knock is still there, or any trouble codes remain, or the oil pressure light is still slow to turn off. If it is, put the electrical sender on the suspect list, especially if it's weeping oil around it's insulator. I just finished all of the above scheduled maintenance on our 2000 Neon at 105K on it, runs like a top, so was worth the cost & effort.
A bunch more thoughts for consideration, let us know how it goes.

 

Check your TPS, that can cause a fluctuation in idle. Fuel pressure is another issue with revving up the engine as well as idling.