Would an EGR stuck open at idle sound like an exhaust leak? Would it cause a misfire condition?

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Dec 17, 2004
Boise, Idaho
Situation - just finished a major refresh - new head gasket, rebuilt head, rebuilt injectors, install TRD supercharger. Used all OEM parts except for the TRD specific stuff. RIg is a "97 1FZ. I have an exhaust leak that I am having trouble finding - it could be the donuts on the Y pipe but it sounds more like it is in the EGR area. Also have an idle misfire - tonight it threw 7 codes for misfire. The rig runs pretty well on the street and highway - good power, no apparent misfires. I am running about 5 deg BTDC on timing.

I am wondering if the EGR vacuum lines are reversed or perhaps the EGR valve "failed" when sitting on the garage floor. Probably a long shot but before I tear the S/C back off to start replacing gaskets I'd like to exhaust all the options (pardon the pun).
If it really sounds like it to s from behind cylinder 6 then inspect the he egr pipe and then its seal to the head. I cracked my egg pipe right where the thin pipe joins the cast mounting area that bolts to the head. It sounded bad like a knock when idling but I don't think it effected how it ran.

Also it is a hard area to access. I had was about to do ahead gasket when mine cracked. So I removed it with the head out. I would imagine you would at least have to remove the intake manifolds to get to the area.
@tominboise did you ever get this resolved? If so what did you find? Thanks
Turned out to be one of the gaskets between the exhaust manifold and the exhaust pipe. I crimped it when I was installing it all together. Pulled it apart and replaced it with another OEM gasket and all was good.
Thanks for the update. Trying to diagnose a recently acquired by my dad ‘97 with a cylinder 4 misfire. It has a slight stumble at idle and sounds really exhausty (for lack of a better word) in the engine bay. Sounds more predominant around the EGR area but it could be a manifold gasket as well.
BTW, when installing the vacuum lines on this car, as part of the S/C install, I had reversed two lines. The rig would not idle at all, as the EGR was opening when it should have been closed.

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