Replaced valve cover gasket, now engine is missing like a mofo.

[03protolx]

I replaced a simple gasket on my 03 protege 2.0L.

Valve cover was leaking oil and decided to replace it. Well, after replacing it and putting everything together the car drove great for a few hours then started to miss horribly. The cel came on and gave me a P0301....cylinder 1 misfire. I replaced the coil on cyl 4 (since thats the coil that controls cyl 1), spark plug, and spark plug wire. it smoothed out just a smidge but still missing. checked spark plug gap and everything is where it should be.

I don't understand how a simple procedure causes my engine to misfire. I should have just left it alone. it runs like hell.

The car starts fine and runs alright...but accelerating is a different story. accelerating from a stop it is really shaky but once it gets up to speed it drives fine.

Car idles fine as well. Anybody want to shed light on the subject?

 

[MaxPower]

Here are possible causes according to the shop manual for P0301:

• Spark plug malfunction
• High-tension lead malfunction
• Fuel injector malfunction
• Air suction in intake-air system (between dynamic chamber and cylinder head)
• Inadequate engine compression due to engine internal malfunction
• Related connector or terminal malfunction
• Related wiring harness malfunction

Have you double-checked your work, especially making sure the CMP sensor is in correct position and plugged in? You can try swapping injectors to see if that changes the misfire code to the cylinder with the suspect injector.

 

[thuzil]

Make sure your ignition connections are all clean. Sparkplugs are gapped and torqued properly. Coils and wire connections are clean and seated properly. Also make sure all of the wiring into the harnesses is in good shape. After 10 years the sheathing tends to crack at the harness and can corrode or break giving some of these symptoms.

 

[03protolx]

thanks for the response guys. Turns out that one of the sleeves that the screws for the valve cover feeds through somehow fell into the cylinder 1 intake valve area. I don't know how it got there and don't know how I missed that, but apparently that is what caused it. it pulls to 80 just fine and idles great.

Thank you guys for all your help!

 

[03protolx]

Update: car started misfiring like hell again. P0302...cyl 2 misfire.

replaced the coil pack...$25.99 @ autozone. runs like new again. figured id put that out there in case somebody runs into the same problem.

the car started to misfire pulling away from a dead stop. felt like a slipping transmission. after a couple hours of driving it progressively got worse and worse to the point the check engine light started flashing.

read the saved p0301 code and the p0302 and replaced the coil pack. all good again.



I hate this car. I really do.