No SES light, I just did a swap - put NGK Laser Iridiums (IGR7A-G '3106') in now the engine back fires at idle and I get almost a bubbling exhaust sound when I rev it.

Any ideas what I did wrong during the process that would cause this?

 

did you gap the plugs properly? .024-.026 for evo 8s.

 

I was under the impressions that the Iridiums come pre-gapped?

 

Well it's not the Spark Plugs, I put the stock ones back in and I'm having the same problem.
I'm wondering if I screwed up my coil packs somewhere along the line.
More symptoms are when I turn the A/C on the idle drops and almost stalls out immediately and a more potent gas smell.

 

bump

 

Faulty IACV? Same thing happened to me when I turned on my a/c after my IACV broke.

 

Turns out I had the spark-plug wires plugged in on the wrong coilpacks. Talk about slapping yourself in the face.

BUT wait there is still an issue, Now the car drives normally but when I drop into neutral and wait at a red light the idle drops crazy low to the point I can't even hear my exhaust. Then It will sort of even it self out after a minute to a normal idle without stalling. I'm going to go back and check to make sure everything is tight but could this be a gap issue seeing as how these plugs came pregapped? I feel like such a newb with all these problems just from plugs

 

Did you have the battery disconnected?

 

Yes

 

That would be the reason. The car will need to relearn idle both AC off and AC on.

Common with most cars but really effects driveability in the evo's

I usually let mine idle for 20min after reconnecting the battery but it could take a few drive cycles to be 100%

 

Every spark plug made comes pre gapped to something. The question is, is it gapped to what you need it to. Evo 8 should be around .024"-.026". Every iridium plug I bought was pre-gapped, but they were at .031". You can gap iridium plugs safely. They make a special tool that doesnt press against the electrode. carefully measure the gaps of the plugs and see if they are correct.

 

^This.

Take it out and do some stop-and-go driving for about 20 miles. It'll be fine.

 

Going to take the plugs out when I get home regap them and let the car idle for 20 minutes, I'll report back the results.

 

You'll want it to learn to idle with A/C on and off and also with some steering pump effort. Let it idle for about 10 minutes then take it for a short slow drvie with lots of stops. That should solve the remaining idle issues.

 

In my experience letting it idle won't help you. You need to get out and drive it, stop-and-go is best.