Spark plug question

[OhSchnapps]

I changed my sparkplugs today. Never doing that in the winter ever again. After changing them and starting up, the rpms went up to about 1,500, then stayed at 1250 for a good minute or so before very slowly reducing to 950, where it stayed. The car was also vibrating very rough, and i smelled unburnt gas. My first thought was that one of the plugs wasn't sparking.

Yes, i did everything right and double checked, doing one plug at a time so i didn't mix the wires up. And they are all securely fastened, covers and all. It was very strange. So i drove my brother to town with the car, and when i got back it was purring a little above 600, and much smoother than before the change. Also, the gas smell disappeared. Maybe i just needed to warm the engine up. My question is, is this supposed to happen?

 

[MikeM6s]

?, I don't think so. Maybe it was the engine adapting to the new plugs. I heard that your car needs a few minutes for that. Sounds like you have it going on now!

 

[SteveSter]

That is normal, your car adjust the timing a tiny bit by itself to compensate for worn out plugs and wires and octane of the gas. Now your car didnt know what to do when you put new parts in it so it took a bit for the timing to re-adjust. Thats why they say you should use a timing light and time it after doing a tuneup.

Did you disconnect and the batt and drain the remaining charge when you did this?

 

[OhSchnapps]

No, i didn't unplug the battery to reset the ECU. And after a few days, i realized that it is doing this every time the engine is cold. Once it warms up, though, it idles fine.

Would resetting the ECU help this?

 

[SteveSter]

Hmm thats wierd, did you use the oem plugs? I believe Mazda used NGK in most models. Resetting the ECU now may not do anything since it already has had time to adjust and obviously something is out of wack.

Does this car have a distributor like the KL-DE?

 

[OhSchnapps]

I bought NGK plugs, and the old plugs were NGK as well. I do not know if this car has a distributor lol, how would i find that out?

 

[SteveSter]

No it doesnt the 2.0L engine is a DIS. Hmm try resetting the ECU by disconnecting the batt and holding the brake pedal down for 30 seconds. Doesnt hurt to give it a try.

Has the problem gotten better or same thing?

 

[OhSchnapps]

So far no change, but i haven't smelled gas since the first time i started it. But i will reset the ECU today and see if that helps.