I have a misfire at #4 cylinder. I plan to buy a new MSD coil, MSD sparkplug wires and NGK (1 step colder) sparkplug for my JCW. Clean the injector too.

Do I need to reset or erase the code or no ?
If the fixes works, is the error code automatically be erased?

 

Yes you need to erase it and no it won't do it by itself. Go to a Pepboys or Advance Auto center (or similar) ask them to read your codes and erase them.

 

If the coil, plugs or wires is the problem your code will go away, it may take a couple days but if that is the problem it will eventually clear after you replace the broken part. It's just quicker to clear it will a scanner or scangauge.

 

The reason I'm avoiding to manually reset is because of the MVD emission procedure.
The car is not registered in my state yet. I read a bunch of frustrated owners that the car needs to run many miles before it can be ready tested for emission. I'm avoiding putting 200 or 500 miles before it can be tested.

I have a problem with that emission law. Why would I run 200 or 500 miles before the OBDII is ready? The purpose of the emission law is to reduce pollutant. Running 200/500 miles pollute more...cost money and time too.

 

but the code will clear itself, like Way says, if it really goes away. For some, plugs are the culprit. Usually it's not the coil, or wires. This is because we have something called a "wasted spark ignition" and it fires the plug at the top of the exhaust stroke as well (this is why we have the coils shaped the way we do). For others, it's a head gasket or valve.

In general, the drive cycles involve starting from a cold start, getting to full operating temp, driving at a bunch of load regimes, and then having the car cool back down. Usually three or so of these reset the drive cycle monitors (But if varies by car, a buddy with a N/A Saab had to go through a hell of a time getting his to reset..... 8 months of normal driving didn't do it. He had to get a driving "recipe" to set them, took three tries!).

But unlike your 7, you should get a good scanner that can tell you drive cycle status. Spend a little more and get one that does CAN version cars too.

Matt

 

Thanks Dr obnxs -- I like your name, look like this avatar
I don't worry about my 7. I'm exempt on the emission.

Yes, I heard a bunch of frustrated owners on the "ready emission stage" issue. Some running a thousand mile and still not ready. So, maybe I will
replace the parts , wait to auto reset if the misfire will be fixed.

Nice info on the plug culprit. I'm changing the coil + wire set + plugs. I don't have much time to do it one by one.