2001 Neon with the 2L DOHC. Has 180k miles. Eats a qt of oil every month, prolly needs new rings.

Its been doing this new thing where it backfires and loses power around 1-2K RPM if its under load. Runs ok if you wait a little longer to shift, or rev a little higher from a stop. Occasionally blinks the CEL and code indicates cylinder misfire.

 

Have you checked the plugs, wires, coil and injectors?

 

Plugs and wires are new since the tube seals went bad a few years back and those parts shouldn't wear. Coil is working fine for the other 3 cylinders, but it could be the issue. Tubes are clear, plugs are fine as far as I can tell. Haven't done a compression test, and I haven't swapped an injector to see if the code follows the #2 injector. I'll give that a go tomorrow and report back.

 

Plugs and wires are new new, or were new a few years ago? The recommended copper plugs should be replaced every 30K, and might need their gap checked if older than that. Wires are every 60K.

 

Did the backfiring problem come about slowly over time, or suddenly after some event?

Have you scanned the engine computer for trouble code clues, if so, post All code Numbers, as they can help focus a trouble shoot.

^+1 on the plugs, wires & coil pack belonging on the suspect list, as they're no longer "new".

Seeing as how we have a "waste spark ignition system" that works it's components Twice as hard as the old distributor model, by having the spark pugs paired together & firing the pair on Every rotation of the crank shaft, (one plug on it's compression/power stroke, it's companion on it's exhaust stroke/waste spark) we need plugs & wires & coil pack designed to take this Double work load. SO, all that said, what replacement plugs & wires were used a couple of years ago?
Also were the plug wires routed exactly as the factory had them? If not, inductive cross firing can occur & that can muddy the trouble shooting waters.
If you come to suspect plugs & wires, or coil pack, warm the engine & raise the hood after dark & have a look around the coil pack & plug wires for a arcs & sparks light show. With a spray bottle of water try spritzing them one at a time while watching for arcs & sparks, or listen for a drop in engine rpm. The coil packs are known to crack underneath & arc to ground unseen. If you think this is happening, raise the coil pack some & spritz it underneath with the water spray.

If the timing has jumped, say from a loose cam or crank sensor, that could cause back fire & if you have trouble code clues for either of those systems or sensors, have a look see at their mounting hdw, wiring & electrical connectors.

Lastly, if all of the above check out, with it using so much oil, combustion chamber carbon deposits could be causing mischief, so consider a top end de-carbon procedure & see if you get positive results.

EDIT: Forgot to ask, With the mileage on this puppy, has the timing belt ever been replaced?

More thoughts for consideration, let us know what you find.

 

I'm an idiot. Plugs are fine, just loose.


Kapow!



Oops

//Facepalm