Thread: Spark plugs

Alright guys and gals, delving further in to the what is my ecm/what has been done to this car.

I’m doing the plugs before work today. I bought the tr6 NGK plugs, I love NGK, I’ve ran them in almost all of my vehicles.

The plug I just pulled out is a delco ITR4A15. Iridium yes, but, if memory serves correct, that is colder than the NGK tr6, correct?

Sooner I find out the better as I’m about to pull them all. They look eh, definitely been in the car a long time.

As of now, looking at the engine, the absolute only mod is the air intake from k&n, stock pulley and all, no exhaust mods, not even the u-bend delete.

Any thoughts?


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I might have been wrong. I don’t think it’s stock manifolds. Just old. And is that not an egr block off plate?

Also, here’s the front one.



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Not sure if the tr6’d are platinum but these engines hate platinum. Use iridium or copper.

I am not sure on the heat ranges.


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Yeah. Sorry. Let me run out and take a pic.


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Here’s a better one, also, found this little guy on the cowl under the hood.



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Originally Posted by Fivefingerdeathpunch

The EGR is on the other side, if it's there. It connects to the intake manifold/supercharger just behind the throttle body and the other hose goes down to the exhaust manifold at the number 2 cylinder.

The block off plate could be for something dealing with a California emissions related item but the picture isn't that great.

That’s what I figured. Maybe air injection? But then wouldn’t the front cylinders have the same?

I’m in California and she passed out stupid smog check. But then again, so did my catless speed density running on E85 with 2000cc injectors STi. Lol.


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And I will also say, it was like a gorilla tightened the plugs in there! I actually had to add a wrench to the ratchet handle to break them loose, but once that was done, they spun out smooth and new ones when in with no hiccups. Honestly the easiest plug job I’ve done. Then again, it’s either been a Subaru or lifted truck I’ve been working on. Once you’ve done plugs on an ej255 without jacking the motor, everything’s easy. Haha.


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Well hell. I’d like to know what it is. Unfortunately it’s not part of any exhaust manifold I have found for OE replacement. It’s definitely a block off plate that feeds in to the head.

Also, on the air pump, every one I have seen is belt driven. Is this one not. I guess I’m too old school?


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Originally Posted by Fivefingerdeathpunch

The air pump would be down by the airbox with a hose going back to the exhaust before the cat.

I forget what else the CA emissions had, likely another smog type system.

Oh, also, the car came from a dealer back east. So maybe it’s a not installed smog part?


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I’ll try on my lunch. At work and we have cameras everywhere.


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Screw it, running out there real fast. Give me 5.


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Here’s some more. I did notice as well, after switching to the tr6 plugs, when it fires up, there’s the sound of a rough start/very small miss for a sec. compared to the delco plugs which would literally bump of the key fast start up. Almost instantaneous.


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I said head earlier, meant manifold. Was getting ready for work so I was rushed.


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Originally Posted by markpa

Not sure if the tr6’d are platinum but these engines hate platinum. Use iridium or copper.

I am not sure on the heat ranges.


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I’m so sorry I missed your post!!! They are the recommended “most sold” plug that zzp stocks. The price was great, that’s why I used them. The same plug at our local Autozone is almost $2 more per plug. Ridiculous, it’s typical California bs.


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That is true. Are these OEM manifolds or some eBay header stuff?


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