[soldier00000027]

Welcome to the forums. There is a rev-limiter to prevent excessive engine speed in Park or Neutral. That behavior is normal. It should get to redline (above 3000 rpm) in gear and under load.

It is important to use OEM (not necessarily Mopar) parts, especially O2 sensors. I have had issues with Bosch and 'universal' sensors. Mopar gets their O2 sensors from NGK/NTK.

Chrysler uses a speed/density calculation for EFI and doesn't use a MAF. It does use a MAP and the TPS is built-in to the ETC (electronic throttle control):

Electronic Fuel Injection Mass Flow vs. Speed Density- Car Craft Magazine

Once upon a time an engine needed three things to run: fuel, air, and fire.

www.motortrend.com

The P0420 is likely real (the PCM uses the before and after O2 sensors to test the cat). The O2s get tested before the cat. You want to be sure the sensors are telling the truth before condemning the cat. The cat is under the 8yr/80K mile warranty, which you may just be outside of?
If the ceramic honeycomb cat element has broken up or melted down, it can restrict exhaust flow, reducing power. It can also be a fire hazard. Any engine misfire that sends raw fuel and oxygen downstream to the cat, can make internal element temperatures soar.

The 'no ck eng' light is bothersome. If the previous owner knew of the failing cat, he may have snipped the warning light LED to extinguish the light before trading or dumping the car, instead of fixing it properly.

There was a PCM software update. It doesn't address any of your issues, but the car may run better with it (if it hasn't been done yet):

https://static.nhtsa.gov/odi/tsbs/2017/MC-10138911-9999.pdf

thank you that was very helpful may i ask where the map is located im not finding it

 

[soldier00000027]

It should be in the front. Attached to the black plastic intake manifold with a single screw (you can see the edge of the P/S pump pulley in the top, left corner of the top image).
The connector has 3 wires: Vt/Br, DB/LB and Yl/Pk.

View attachment 57784

It should be in the front. Attached to the black plastic intake manifold with a single screw (you can see the edge of the P/S pump pulley in the top, left corner of the top image).
The connector has 3 wires: Vt/Br, DB/LB and Yl/Pk.

View attachment 57784

ok thanks for information i found it too easy , right in front i was it dam sure aint in back lol, you really helped me alot thank you so i got it and now im putting it on i let u know what happens after i replace with new one and clear out all codes and see if anything changes and after i drive car as well around the block.

 

[soldier00000027]

ok i drove it around the block for a few miles local stayed by house in case lol, but i had some good straight roads for a distance and best in beginning i could do was almost 40 mph but then on next time i try ed it would only go 22 mph and not pass 2200 rpms and when i pressed on gas pedal to see what would happen , it was like a slight knocking in engine for about 3 to 4 seconds then stop strange, i even went and put 1/2 tank of best gas in it nitro gas 91 cent and i poured one of the cat cleaner in there and then drive around but pretty much same thing, not a real lot of difference after all that work and right back to same code p0420 with same thing as before even when i cleared them out with my code reader and then did test runs ......hhhmmmm lost well letting it cool off and resetting the throttle body controller so gotta wait 1 hour and re try again and see if any changes, i dont know now and still no check engine light no lights at all and yes the check engine does work i seen all the lights and they all work come on and when start car all go off i dont get it hhmmmm, also i noticed something like u know on the dash the cold anbd hot temp for oil/engine i noticed when i stopped to clear code out it would come back on at 3/4 way like hot but then as im moving it starts to go back to normal but to me the engine seems hotter than it should be after 15 minutes of driving , but its not showing hot really , you think maybe needs a new thermostatic prehaps i didnt even turn ac on and when i do its about the same really. hhhmmmm

 

[soldier00000027]

Make sure the radiator fan comes on. You need it at a stop or moving slowly. Going down the road, enough air is blowing through the radiator that you shouldn't need the fan.
Turning on the A/C should bring the fan on also, as it has to cool the condenser in front of the radiator.

You may need a cat? If so, look for an inexpensive 'direct fit' as long as you don't live in California, NY, ME or CO:

Davico® - Direct Fit Catalytic Converter and Pipe Assembly

Catalytic Converter and Pipe Assembly by Davico®. Converter Configuration: Direct Fit. Position: Center. With 2 O2 Sensor Ports. Catalytic Converter Overall Length: 38.75". Davico 19393

www.carid.com

ok well the fans both fan come on when its started while in driveway, and when i turn the ac on , then i see and hear both fans kick in because of the ac so all that seems to be fine and temp is normal but dont u fine its weird that i dont have an engine check light on at all or any lights and all my lights work i see them come on right before i start the car

 

[soldier00000027]

ok well the fans both fan come on when its started while in driveway, and when i turn the ac on , then i see and hear both fans kick in because of the ac so all that seems to be fine and temp is normal but dont u fine its weird that i dont have an engine check light on at all or any lights and all my lights work i see them come on right before i start the car

oh and i live in bossier city, lousiana lol and milage is 89,000 on car

 

[soldier00000027]

The 'ck eng' light should work if it passes the bulb check at start up. Has the previous owner modified or hacked the PCM in any way?
You should be able to 'make' the light come on by unplugging a sensor or relay (A/C for example?) and then start the car.
If you erase the P0420, it will usually take 2-3 days to set the code again. It shouldn't come back right away. Are you sure that the scan tool is erasing the code?

yes the scanner or coder reader is erasing the code and i even did it with the 10 fuse they say to take off for a hour i did both p0420 comes back everytime and says permerant, today we just for the **** out it replaced exhaust and intake camshaft timing solnoids, and cleared the code every time same thing comes right back but again still no check engine light i dont get that just the code

 

[soldier00000027]

yes the scanner or coder reader is erasing the code and i even did it with the 10 fuse they say to take off for a hour i did both p0420 comes back everytime and says permerant, today we just for the **** out it replaced exhaust and intake camshaft timing solnoids, and cleared the code every time same thing comes right back but again still no check engine light i dont get that just the code

yes the check engine works as it should be and nothing wrong with it, but when i test drive it after 15 mins i stand in front of engine and alot of heat be coming off that engine hotter than normal and my hearing not the best but like when i go up around 20 mph it does sound like a hole in muffler but not from back down below i kinda stuck my head out drivers window and i can hear it like down by engine so im starting to think it really is p0420 the cat after all this work

 

[soldier00000027]

I just saw this in the other thread and brought it over here. A battery disconnect or fuse pull used to reset computer memories and erase fault codes in the old days, but not on newer cars. Any reset has to be done with a scan tool.

The 'rattle' on acceleration is not good. It could damage the engine. Does the car have the correct spark plugs in it? What color are the tip insulators? Are they black (rich) or white (lean)?
If the cat is broken up inside and restricting exhaust flow, it will do as you describe.

i dont know about the tips its gotta too dark outside and i work in morning so i look tommorow and let u know , do u think could be spark plug or coil, possible???

 

[soldier00000027]

i dont know about the tips its gotta too dark outside and i work in morning so i look tommorow and let u know , do u think could be spark plug or coil, possible???

but not misfire is green on code reader only 3 blinking red lights on my code reader 02 , evac or something like that and cat thoses 3 red blinking all others on code reader green

 

[soldier00000027]

yes the scanner or coder reader is erasing the code and i even did it with the 10 fuse they say to take off for a hour i did both p0420 comes back everytime and says permerant, today we just for the **** out it replaced exhaust and intake camshaft timing solnoids, and cleared the code every time same thing comes right back but again still no check engine light i dont get that just the code

yes im sure the code reader even says erase successful but when it reruns it comes right back on but like i said strange no check engine light and yes it works check engine light if it was a bad cat wouldnt check engine light stay on hhhmm

 

[soldier00000027]

A P0420 shouldn't come back quickly. It should take at least a couple of days to retest and set the cat code.
Spark plug color may help in diagnosing a fuel or mechanical problem. The plugs should be either Champion RC12MB3 or RC12MC4 depending on which 2.4L you have. There was a standard LEV (low emission vehicle) and the PZEV (partial zero emission vehicle). Having the correct plugs are an important starting point.

The PCM may have a problem if it can't turn on the 'ck eng' light (we know that the light itself works). If you can get to a parts store, try their customer-use code reader to see if you get the same P0420.
Some generic code readers may not work right on all OBD2 cars.

Save your money, don't keep replacing parts until we can get a handle on what the car actually needs.
Do you know any of this car's past history from the previous owner?

no i dont know this car s past history, its a friends car , i check out spark plugs this evening after work let u know. and i take it and have them read it at parts store thanks