Hello,
To start, I am NOT talking about rocker arm tick here. I already had that issue and fixed it by replacing rocker arms that i heard tick. I am talking about underload (e.g. driving up a hill) detonation (i.e. pre-ignition). It mostly happens around 2k RPM.

Background: 2005 Dodge Neon SXT 2.0L with 121k miles. Started hearing the knock at around 116k miles. Only repairs in my log book near 116k are a replacement remote car starter, replaced 3 exhaust rocker arms, new rear struts, and new serp belt tensioner (yeah I should have done this with the timing belt...) at 115k. I did the timing belt, water pump, new spark plug wires, lower engine torque mount, and coolant flush at 107k.

Here is what I have tried to fix (in order of my attempt)
1) Running premium for 8 tanks or so now. 4 of those tanks had injector cleaner
2) Replaced knock sensor and the tranny mount at 119k
3) Checked intake for leaks with starting fluid then checked and cleaned MAPS sensor at 120k
4) Unrelated, but maybe worth noting, I just had the transmission fluid flushed and replaced at 120k.
5) I can re-create the knock doing a torque stall (foot on brake and gas at the same time). I did this while a friend unplugged the injectors one by one. Doing this, we narrowed the knock down to cylinder #3 (middle driver's side). That is to say the knock went away when we unplugged the injector for cylinder #3, but remained there for all other cylinders. So I replaced the injector for cylinder #3 thinking it may be running lean.

Nothing has worked so far and it seems like it's only getting worse...

Special Note: Sometimes when I hear the knock I can press the pedal down a ways and the knock will stop. My theory here is that when I do this I flood the chamber with gas and that lowers the temperature. So in certain conditions light pedal = no knock, medium pedal = knock, heavy pedal = no knock.

My Questions
1) What else can I try?
2) Does this thing have an EGR valve?
3) I have heard Neon's have issues with cracked pistons. The idea being that the sharp edge of the crack gets red hot and pre-ignites. Have you heard this?

Really appreciate your time and any comments, thoughts, or experiences you can share,
-Troy

Update #1: Well the neon started to struggle to start. It would turn the starter about 10s when it was cold (like single digits cold here in da UP) before it would start. So I knew the battery was good. I replaced the fuel pressure regulator/filter, because i never had and with 122K it could have been that. I then went and borrowed a fuel pressure tester and a compression tester. Since the 2005 Neon does not have the nice schrader valve like I hear some Chrylers do, I had some issues getting the fuel pressure regulator to work.

Ultimately, the compression tester showed me cylinders 3 and 4 only had 60 psi. 1 and 2 had 160psi. The book says 175-225psi. When I put some oil in cylinder 3 and re-tested it, the psi went to around 80psi. Since cylinder 3 and 4 have the issue, I assume its a head gasket issue. I haven't noticed oil in my coolant or coolant in my oil, but I haven't look yet either.

Does any one know of a good online guide/video for replacing a head gasket on a neon?

Update #2:
Well turns out my head was shot, so I had to replace that and my gasket. Doing this job fixed all of my issues. Here is a videoing showing step-by-step how I did it:

 

I've been experiencing almost exactly the same issue you seem to be describing here. Tapping/knocking noise, couldn't find exact source of it, eventually checked compression and had about 50% compression in cylinders 3 & 4. Also an '05 SXT.

Been working on pulling the head for the last few days after work, and finally got the head off earlier today. Found quite a bit of scoring between each cylinder, with a clear breach between the problem cylinders 3 & 4.

Here are some pics:

 

Thanks for the note SecuritronX. I got my head off last night and my break looks exactly like yours. Did you figure out what caused your break? My head had some pitting:

Does your head have pitting?
Does your head have an EGR valve? Is it by the cam sensor?
Lastly, how did you clean up your block? Looks great!

Thanks again for saying something!
-Troy

 

Not really sure what caused the break, but based on what I've been reading about Bosch Platinum spark plugs and Neons, I'm wondering if maybe that could be it. I had put Platinum +2's in awhile back and didn't change them until after I first noticed the symptoms. It seems some people have had issues with the platinum plugs and misfire/detonation issues in Neons.

As for pitting, I had nothing as severe as that; that really sucks. I just had a burn mark between 3 & 4 that was fairly rough and scratchy. It may have developed into pitting eventually though.

No EGR on my car that I know of. Just PCV and make-up air hose coming off valve cover, I think.

For the block, I mostly used alot of brake cleaner and a brass detailing brush. Then I went over it very lightly with a machined steel sanding block (for guitar fret leveling) using wet/dry 1000 and 1200 grit paper and some WD40.

Probably not the wisest of ideas, but seems to have worked out okay. Checks out with a straight-edge and .004 feeler gauge, so should be alright. Definitely looks better than it did.

Probably won't know for sure until next weekend, as nobody around here seems to have the proper valve spring compressor tool needed; and I would like to change the valve seals and grind the valve seats before reassembling.

 

Very interesting on the spark plugs. I haven't read that. I put in Autolite double platinum 3923's at 97k miles (now at 122k. started knocking at 116k). So maybe that was my issue too. I cleaned my head and block with scrubbing bubbles and a brass pad and they both checked out with a 0.004 feeler as well. So my best theory is just that my head gasket blew and created a sharp edge in cylinder 3 that would pre-ignite the chamber it got so hot. Then the detonation caused the pitting, because I didn't find it fast enough. I knew it was cylinder 3, because I could replicate it with a torque stall and had someone pull the injector connectors one and a time. The test showed the knock stopped only when we pulled cylinder 3 injector connector.

As for the EGR, i figured out starting in 2000 they stopped putting EGR on that head. If you had an EGR, it would be mounted down and to the right (toward the rear of the car) of the cam sensor.

I get my new head Tuesday or Wednesday, so we'll see how it goes. I guess I buy some new plugs too Any recommended plugs you found in your research?

Thanks again!

 

It seems copper core is most recommended; most often NKG V-Power or standard Champions. Apparently platinums don't play well with the Neon's waste spark ignition system, which can cause them to wear prematurely and unevenly, leading to misfire issues. Double Platinums are supposed to be compatible, but some have had issues even with them:


http://forums.neons.org/viewtopic.ph...um+spark+plugs

https://dodgeforum.com/forum/2nd-gen...your-neon.html


Still probably a shot in the dark, but there does seem to be at least some supporting evidence.

 

Well I don't see anyone saying copper didn't work for them. So I'll go with that. Thanks for writing back!

 

Well I finally got it running yesterday. Made a video of how to do it for those who find this post later on:


You can also find more detail on my website:
www.TroyBouman.com/neon

The topics covered in the video are theses:
Topics
Remove crank cover (bolts x3)
Remove battery negative
Remove fuel relay
Remove starting coil (bolts x4), coil plug, & spark plug wires
Remove valve cover (bolts x10)
Remove two vaccum hoses attached to valve cover
Remove spark plugs
Drain cooling system
Remove intake manifold
Remove fuel rail
Remove air intake from throttle body
Remove upper radiator hose
Remove thermostat & housing (bolts x2)
Remove MAPS sensor plug
Remove fuel injectors
Remove brake booster hose
Remove intake support bolts x2
Remove intake bolts x5
Remove A/C compressor clutch plug
Remove knock sensor plug
Remove starter cables and plug
Remove timing belt
Remove crank bolt
Removes serp belt and alt belt
Remove crank damper puller
Remove power steering pump (bolts x5)
Remove hose/ground holder (bolt x1)
Remove upper torque strut (bolts x2)
Remove right engine mount (T55 Torqs x1)
Remove timing belt plate (bolts x3) & outer cover (bolts x2)
Remove timing belt
Removing timing belt back cover (bolts x2) & belt tensioner (bolts x2)
Remove cam shaft sprocket
Remove front cooling hose (bolts x2)
Remove cam shaft sensor plug, support (bolt x2) , & coolant temp sensor pluig
Remove exhaust temp sensor & heat shield (bolts x3)
Remove exhaust manifold (bolts x8)
Remove cylinder head
Swap cam shaft sensor (bolts x4) & engine coolant temp sensor

Other topics discussed
How to fix engine tick when its cold
How to find top dead center for cylinder 1
General inspection once taken apart (things to look at)
How to clean up the head and block surfaces
How to check for head warp
Does it have an EGR valve?
How to replace rocker arms
How to replace your timing belt, water pump, and belt tensioner
How to time your engine