[Unoriginal Name]

I had my Corolla in for an oil change two weekend ago. They told me that I also needed to have my engine valve gasket changed since it has begun leaking. I opted not to get it changed at that time but will have it changed some time in the near future.

On Sunday my wife was driving the Corolla and she noticed that at first it would be slow accelerating and would even stutter at times until she got to a certain speed and then things were fine. Once the car was driving for awhile this problem went away.

On Monday I drove the Corolla and everything was fine.

Yesterday I drove the Corolla and things were fine in the morning. In the afternoon I noticed the slow acceleration and the stuttering. It seemed to stutter until it got to 30 - 40 mph and then it would be fine. At the same time the CEL came on. A couple of times while accelerating it would blink which I know is very bad and it needs to be checked out right away so I was going to do that when I got home. After some time of driving the CEL stayed illuminated but it no longer blinked. Since it wasn't blinking any more I went to Auto Zone to pull the code. It was P0302 Cylinder 2 misfire. The guy told me it could be a dirty fuel injector or it could be that the plugs and wires need to be changed. I tried injector cleaner and so far so good. I want to change the plugs and wires....what are some recommendations on good plugs? I see Auto Zone has many different ones for my car.

Also, are the leaking engine valve gasket and the CEL and stuttering problem all related?

[fishexpo101]

The appropriate plugs and wires would depend on the model year of the Corolla. In some past posts - you mentioned you have a 7th gen Corolla (1996 model year) - we talking about the same one?

That case, I'd go with some Denso or NGK copper plugs. If you want something to last a little bit longer - you can opt for platinum or iridium plugs. They cost quite a bit more, but their replacement interval can go up to 60K miles with some platinum plugs, and up to 120K miles with iridium plugs. If you don't plan on changing the valve cover gasket at the same time as the plugs, I'd go with the copper plugs. If they get fouled between the time you installed them and when you get time to replace the gaskets - you can just pick up another, fresh set.

If the car is still on the original cap and rotor and plug wires, would be a good idea to replace those. Toyota OEM parts are pretty hard to beat - if you shop around, they can be had for not much more than aftermarket parts. They've already lasted this long, and you know fitment will be perfect. Same with the gasket - that generation had individual o-rings for each sparkplug tube and some of the longer valvecover bolts. If the gasket is leaking by the tubes, it is possible that oil is pooling at the bottom and causing a misfire. You can do a quick check, but pulling up on the boot and shining a flashlight down the tube. Note any oil or stains at the bottom, check the end of the plug wires and see if they got oil/stains on them as well. If you have the right tools on hand, you can pop the plugs out and "read" the plug ends.

And yes, the leaky valvecover gasket, CEL, and stumbling can all be related. A misfire will cause the CEL to pop up for the suspect cylinder (#2) and the car will seem to be down on power - since it is not firing on all cylinders.

[Unoriginal Name]

Yeah it is the same car. While I was driving home from work it dawned on me that I forgot to mention the year of the car.

As far as I know this is the original cap and rotor as well, so I guess it is a good idea to change that. How difficult are these items to change on my own? I know how to use tools but I don't know much about cars. I have changed plugs and wires in the past but I had someone gap them for me.. I imagine that the gasket might be difficult...at least it sounds difficult. What about the cap and the rotor?

If I go with Toyota OEM, which I would like to do, how do I go about finding where to buy from besides the dealer? Are they available at Auto Zone type stores?

Thanks for the help.

[fishexpo101]

Replacing the cap and rotor is well within the reach of your average DIYer. The valve cover gasket is actually not that bad, just sounds more difficult. The tricky part there is the torque on the long bolts that pull the valve cover to the head - a little too much and you will crack the pop-metal valve cover. The cap and rotor - pretty straight forward. The cap is held on by three? bolts, rotor is right underneath it. Before you take it off, make sure to label the plug wires or move the wires, one at a time from the old cap to the new one (can do this as you replace the plug wires - just move one wire at at time to guard against screwing up the firing order).

Other than the dealership - you can try online sources. Many had very good luck with www.1sttoyotaparts.com - as they are both a online retailer as well as a physical Toyota dealership - they stock the same parts but generally give you a much better price break. Can also ping on the parts guy at the dealership - most of the time, they sell at MSRP, but you can get a "cash" price - which can shave off a few bucks here and there.

[Unoriginal Name]

Thanks fishexpo.

The curious thing is that the stuttering seems to only happen when it is wet outside and once the engine warms up the stuttering disappears. Does this sound like a wire/plug issue? Or could it be something else?

Also, I'm looking around www.1sttoyotaparts.com and I'm having some trouble finding the parts. Is there anything special they call spark plugs, the wireset, the cap, and the rotor?

This post has been edited by Unoriginal Name: 09 October 2009 - 07:13 AM

[fishexpo101]

Those should be under "Electricals" and then under "ignition system" - should be cap, rotor, cable set - I believe. May not have them in stock, so they might not list a part number. Another good site is www.rockauto.com - they carry mostly aftermarket parts, but have some of the best prices around.

The stuttering happening when it is wet outside and goes way when the engine is warmed up - are almost sure signs of a bad sparkplug wires, cap and rotor. Under high moisture conditions - any cracks in the wires, cap and rotor - can cause misfires or weak spark events. This will cause the engine to "stumble" as it is not running properly. As the engine warms up to operating temperatures - the heat from the engine will drive off the moisture and cause any small cracks to close up (thermal expansion) - causing the problem to seemingly go away.

[Unoriginal Name]

Another dumb question.....would I be better off getting OEM parts from an online source and having to wait to change the parts or would I be better served to go to a local aftermarket shop and get the parts changed right away? What other potential damage could be caused to the car by driving it while waiting for OEM parts to come in from online?

If I got aftermarket what brands would I want to avoid for the other parts? I saw your recommendations on brands for the plugs.

Thanks for all the help. I really appreciate it. I hope I haven't been too much of a pain.:)

[fishexpo101]

The brands will vary from store to store - honestly, most of the ones there are probably going to be pretty close to one another. Many carry Beck/Arnley, BWD, Accel, Cardone, Xact, and more. Doesn't hurt to ask if you can see all the ones they have - side by side - you can make a fairly decent call which one looks better. Sometimes looking at the warranty will help - ones with lifetime warranties can be manufactured better, but not always. You can also print out the price list for 1sttoyotaparts or rockauto and see if the dealership will match prices.

Car won't blow up right away if you don't get the parts immediately, but stuff like this can easily be put off with other unforeseen emergencies. If you have some time blocked off to work on the car I wouldn't hesitate to use something else of decent quality. Just double check with the autoparts store return/exchange policy. Some will not take back parts once they leave the store for any reason, other will charge a restock fee - even if they gave you a wrong part. Up to the consumer to verify that they got the right part before they leave. That's the biggest advantage of OEM parts - almost 100% fitment is assured if you buy OEM - but there is no need to pay through the nose to get that either.