Hey guys!

As any of you who have seen my posts before know, I have the neon from hell. New developments, however, might shed some light on the situation.

My neon is throwing codes for running lean, rear 02 sensor reading high, and the fuel-pump relay reading constantly on. The thing gets about 16 or less mpg. I have replaced all sensors related to fuel/air mix and the pcv valve. The problem is getting worse.

Today, the neon started violently rocking above 2,000 rpms and blew (!) the ignition tube off the second spark plug. The engine was making a very slight thump-thump-thump noise before, which I thought was just the old belts wearing down, but I noticed as I inspected the engine after the incident that the sound is actually coming from the second cylinder and you can feel the spark plug tube pulse with each sound (again, !). When I pulled the tube off a little more with the engine running, the sound sped up and the engine responded like when you take a vacuum tube off.

Is air getting into my engine through a completely destroyed tube seal? Is that even possible? I can only think compression could have blown the plug tube off. Any chance of a crack in the block or something? Should I start thinking about changing the valve cover gasket and seals, or is this engine a goner?

Thanks guys.

 

have your tired replacing the spark plugs and wires... sounds like you have an ignition miss... for sure... i would deff try replaceing them and see what happens... its the place to start...

 

Yea, I changed the spark-plugs recently.

I could try changing the wires, but that can't be what's causing the tube to blow out and the sound. I imagine there's gotta be a compression leak around the plug.

 

is the plug tight? check maybe its come loose

 

Good idea, I'm at work now but I'll check it when I get home. I hope it's just a loose plug, but I know that the thump-thump sound (which I now know is air exiting the cylinder) was there long before I changed the plugs out.

Apparently spark plugs blow out of Ford trucks all the time:
http://www.denlorstools.com/home/dt1...to_repair.html

Wonder if I have a similar problem. I hope it's not the plug threads.

 

I would change the valve cover seals. I would also check to make sure no one ever "rigged the wires for the fuel pump, or rigged the pressure regulator in the back. I would also check your pvc. Sounds like you have a neon that someone didnt take care of. I drive my boosted neon daily and I dont have any issues with anything, neons are great cars.

Another thought: make sure your spark plug "tube" isnt loose.

 

spark plug threads getting messed up on anything with aluminum heads is really common... its fairly easy to fix but its best that you remove the head to do so... although i have done it with the head on the engine and slowly tap it out for the heli coil.. making sure i had some grease on the tap... and only go in a lil bit like half a turn at a time and then back out and clean the metal shavings off... takes forever and kinda messy with the grease and shavings but it works and saves taking the head off... if thats your problem anyway...

 

I agree, if your spark plugs aren't sealing, check that they are right first. They aren't a taper seal, it should have a flat metal gasket. I would start replacing plugs first. You could chase the threads with a spark plug thread chaser still on the car. Unlike a tap, the chaser isnt going to cut new threads, but if you still can't get the plugs tight and they keep spinning, then the threads are stripped out.

Also, if your problem is coming from the valve gasket somehow around the spark plug hole, then you may have bad rings and should check compression. you should get 100-180 from all cylinders. If one varies from the mean say like you get 135-125-140 and 90, then that 90 is your suspect.

First of all, check that the plugs are right and tight.

 

Wow guys, thanks for all the responses! I checked the plug and sure enough it had come loose. I bought and installed a replacement and the car is running, but I can still feel a "thump-thump-thimp" on the tube if I put my finger on it. The tube will definitely need to be replaced given all the sooty buildup on/in it now, but I doubt that's the core issue.

The new plug seemed to fit alright, and seemed to go straight into the threads, but I dunno...I'm still suspicious.