My car failed the most recent emissions test. HC 235 (limit 220), C0 5.38 (limit 1.20). However, the car was still running just fine, felt the same and as strong as when it passed the previous emissions test a year ago.

So I figured I would start addressing the situation by replacing the sparkplugs.
I changed the oil and then installed brand new NGK BUR7EQP and BUR9EQPs (same as before), paying close attention to where they go (7s=leading 9=trailing).
The old plugs had a lot of soot and gunk on it.

After putting the plugs were in and restarting the car, I immediately noticed considerably a lot more white smoke coming out of the tailpipe and a very rough idle (500-900RPM). I turned the car off, inspected everything again to make sure the plug wires were inserted correctly and all the way in.

After restarting the car - same rough idle for a few seconds and then the engine cut off. I haven't started it back since. I'm planning on taking everything apart again and inspecting/reinstalling as soon as I can.

In the meantime, does anyone have some advice that can help me?

 

Check the map sensor pipe/ electrical connection incase you knocked it off. Rix

 

I would replace all 4 plugs with NGK BUR 9EQ....NO P I see the P do not hold up too long. I been using 4 9s since in all my cars..

Check making sure you did not unplug anything in the area... Did you swap wires if so make sure you did not damage any on the hoses under the intake...
Since you will be pulling the plugs have some one crank it when the plugs are off and listen to make sure all the compression hits sound the same.. I does place my finer over the plug opening and have someone craks the motor and feel the pressure making sure the compression is even...

 

^make sure you unplug your fuel pump relay before you turn the motor over without the plugs.

The white smoke is what really worries me though as white means burning coolant. Most of the time when the map sensor comes of it runs super rich which means black smoke. i would start with the simple stuff, wire in correct spot and the map sensor vac line.

 

Did you mix the plug wires up?

 

My first guess would be the plug wires were on wrong, but you said that you are 100% positive that you got them all in the right place, right? Then, I would think that for some reason, you're not getting a spark from at least 1 spark plug.

Did you use anti-seize on the threads, and if so, did you make sure to not get any anti-seize on the tip of the plug?

Did you make sure that all of the plug wires "clicked" into place on the spark plug? Sometimes, the metal contact inside of the plug wire boot gets pushed back a little too far for it to make good contact with the spark plug. When that happens, you need to push the plug wire through the boot a little further so that when you push it onto the spark plug, it sort of clicks into place.

 

Most likely that your wires are not on all the way, or you broke one while removing them.

 

It may sound unusual, but I after confirming all connections & plugs are correct, I would replace the plugs.

It is rare, but you can get bad plugs from the factory. I had this issue with my old GSL-SE. It stumped me for a week. Two were bad. Brand new plugs, two dead from the factory.

 

Looks like you over/under torqued some/all plugs and/or you criss crossed the plug wires.

 

^yep check the porcelain/white part cause that happened to my friend vette.

 

I finally got the chance to look into it this past weekend. I checked all the wiring and everything looked intact. What I did next was simply change out the brand new plugs and re-install the old plugs (the ones that ran well) and started the car up - same rough idle and white smoke.

So now I'm not sure what else to do so I decided to just take the throttle body out completely so I can get a closer look at the the wiring and plug connections. Also took out the oil filler neck (see pic) Nothing seems out of place.

Any other suggestions?

 

check that you have spark at all wires/plugs. verify map sensor is connected if you have a pfc do the sensor check

 

Follow the Mazda manual instructions and check the wires and coils with a meter.

Otherwise, buy a new Malloy engine and install it yourself.