My 05 revup just hit 100k miles on it, so I decided to swap in Iridiums. I recently bought the car, and assume the plugs have never been changed. They weren't, and I've never seen spark plugs look that bad. I expected at least 100hp, as the gap was into the 0.70mm range. I installed the plugs correctly, didn't unplug anything but the coil packs. The torque increase in the low end was amazing.....for a few days.

Now, I'm almost thinking about swapping my 100k mile plugs back in, as all I have is rasp, a loud exhaust and a very noticeable power loss. Under no circumstances can I even get the tires to chirp, even when inflated at 45psi. Checked over the entire car, which is stock, (minus the exhaust), and found no issues.

Has anyone else had an experience like this?

 

Doubt it's just the spark plugs, probably a combo of maintenance related issues.

 

Stopped up cats?

 

I have Megan v2 test pipes. Only code I have is for rear 02 sensors

 

Sounds like you dropped a cylinder

 

Is it misfiring? It is easy to mix up the plugs that go to the coil packs for the middle and rear cylinders on the drivers side.

 

So, did you check the correct gaping of the new plugs you replaced with 1.10mm from the old bad 0.70mm gap plugs?

Let's us see the pictures of those old plugs look like, so maybe we can tell what is wrong with your engine.

 

You either messed up the install or your computer reset if you had the battery disconnected during the change and now it's re-learning in a way you don't like.

 

100hp off plugs?

 

Is your engine running smoothly?

I ask because the power loss you describe sounds as though you lost a cylinder (running on 5 now).

I have the same question crsrasing19 asks: "100hp off plugs?"

--Spike

 

What is the gap supposed to be at? Did you try and gap any of those plugs?

 

Damn, Im getting some new plugs.

 

I’ll bet you are on the right path here to discover the problem. He states that there is a problem with the oxygen sensors:
--Spike

 

im about to install some plugs and forget about motordyne parts haha