How's it going? google has sent me here a quite a few times in the last month or so, so it seemed like the best spot to ask for advice :0)


i have an 03 neon sxt automatic. experiencing rough idle at stop lights about 95% of the time. putting trans in neutral always makes it stop and idle smoothly again. typical idle rpm is a bit under 1k (per tack) when it gets rough it drops to a bit above 500, then putting it in neutral makes it go to ~700 and smooth out.

also pretty bad hesitation when slowly accelerating. like when going 70 on highway and wanting to pass someone by gently pushing the pedal to gain 5 mile per hour. if i floor it it accelerates decently. but gentle acceleration almost always results in engine strain and little to no acceleration. same issue at slower city street speeds too.

i have replaced the PCV valve, camshaft position sensor (OEM), crank position sensor(not oem), plugs, wires. and a few parts off my 02 manual neon (TPS, MAF, coil. just to see if it helped.) im thinking o2 sensor(s) since from time to time i get a p0171 bank 1 too lean error.

i just did oil change / pan gasket, and same for trans. fuel pressure is just a hair under 60. 58, 59 maybe. moves just a bit closer to 60 when ya hit the gas.

havent pulled the injectors to see if they are spraying properly. Just ran a tank of premium with Lucas fuel system cleaner. no change in performance.

3/4 spark plug tube seals are bad, so plugs have oil on the top side.

im slowly working to fix everything wrong, but money is not something i have lots of. just need to get this fuel / sensor / acceleration issue fixed first. also on my 02 neon i could get 350 miles per tank almost every tank. this one i have yet to break 285.


first owner of the car had some sort of front impact. can see where parts of the front clip have been replaced, also intake manifold had salvage yard writing on it. so who knows if it was ever put back together properly.

any ideas / advice would be much appreciated! thanks, Josh

 

Check the motor mounts. If they're torn/messed up, change them and you'll see a difference.

 

The wife's Neon had the rough idle problem even with a new engine mount and torque struts, so I turned the idle adjustment screw about 1/4 turn and it helped a lot. At least she hasn't complained about it since then

 

idle adjustment screw???? where is this locatied?????

 

It's on the throttle body. If you grab the throttle plate (where the cables attach) and turn it, you'll see a little bolt with a 10mm head on it. That's the adjusment screw.

 

After doing more research I've learned that turning that screw could change the output voltage from the TPS which could mess with the computer, so I wouldn't get carried away with it. It seems that a lot of Neon owners have the rough idle in gear problem and I've found a lot of suggestions, but no real solutions, except for a guy who had his computer reflashed. I checked just about everything except for the transmission mount, which I will probably check next. I did find a TSB http://www.ertyu.org/steven_nikkel/n.../18-013-02.pdf, which addresses this issue and the fix is to reflash the computer. I don't normally pay somebody to work on my car, so I have no idea what that would cost. If anybody has any ideas other than drilling a hole in the throttle plate or altering the IAC, I would be happy to hear them.

 

I tried all 3 of those things to no avail. The only results were that I wasted $100 on a reflash/update and had to buy a new throttle body because between messing with the idle adjustment screw and drilling a hole in the throttle plate, I could never get the car to idle correctly again.

 

I'm pretty much convinced that my O2 sensors are bad. Any one had luck with denzo sensors? Dealer price on both are almost 200$

 

Denzo or Denso? Denso is good stuff.

 

just had both O2 sensors replaced and car runs great now!


well...... let me reiterate did run great...

left me stranded tonight had to bust out a window, see this post...

https://dodgeforum.com/forum/2nd-gen...ml#post2909589