z31p_Amadeus: Forum archive import (z31performance)

2026-05-15T05:18:19Z

Forum archive import (z31performance)

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{{ForumImport
|op_user=Amadeus
|op_date=2010-02-21 00:22:10
|post_count=11
|archive_url=/Z31performance_archive/forum/z31-repairs-forums/engine-mechanical/9623-engine-stumbles.html
}}

'''Amadeus:''' (2010-02-21 00:22:10)

Hey everybody looking for some help. Today I pulled off the intake plenum so I could replace a broken pintle cap on one of my injectors and also replace the injector seals, also put in new spark plugs. But after putting it all back together I developed a problem with keeping it running. It'll start up and thenit begins to stumble really hard and I'll hear a hissing noise from around the throttle body area, and when I give it some gas I'll begin to hear a popping noise coming from I think the Intake manifold. I've looked under the hood and don't see any vacumm lines off nor do I see/smell and gas leaking. The only thing I can think about is that I have a leaky gasket between the plenum and the lower manifold.

Any ideas?

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'''perna00:''' (2010-02-21 00:33:01)

If it is hissing that badly, take some starting fluid and spray it around the seal between the upper and lower plenum and see if the idle changes. If so, leaking gasket. Take a screwdriver to each injector to feel if they are all pulsing since you worked on them.

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'''Careless:''' (2010-02-21 07:31:47)

I've been hearing a slight hiss in that region near my throttle body too… I'm not sure if I used a paper or a metal gasket for the plenum gasket…

which did you use?

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'''Amadeus:''' (2010-02-21 08:17:30)

I reused my metal one. Cause everything that I had read said that you could reuse metal ones as long as they wheren't damaged.

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'''Careless:''' (2010-02-21 10:35:00)

Did you ever sand or scuff the mating surface of the plenum or the lower intake manifold?

I resurfaced mine with a surfacing disc… but at this point I'm not sure if it was done well enough. It may be rounded out a bit at the edges, but it looked smooth… I'll have to re-torque the bolts to see if they're OK..

Have you tried checking the bolt torque?

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'''Amadeus:''' (2010-02-21 17:59:19)

Yep cleaned off the matting surfaces and tightened the bolts with a torque wrench like the FSM says.

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'''Careless:''' (2010-02-24 06:24:42)

same. I used a paint stripping sponge that I used on everything else, so I don't know if it's leaking from there.

Does the throttle body seal leak under boost? I got a Stanza TB and It was one of the only things that I actually changed, mechanically, during my vg30 repair that also developed the whistle....

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'''Amadeus:''' (2010-02-24 14:31:29)

No the TB seal doesn't leak. I'm just going to replace the plenum gasket cause it's a $5 repair and I'm almost 100% sure that that's where the leak is from.

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'''Amadeus:''' (2010-02-28 01:32:37)

Well it turned out to be the plenum gasket. Replaced it with a new gasket for a 2000 Xterra and it runs like a top now, just need to tighten up a couple of the intake clamps.

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'''michaelp:''' (2010-02-28 01:51:05)

intake manifold gaskets these days..pff. LOL

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'''Matt89:''' (2010-02-28 16:11:12)

No, it is not ok to reuse the metal gaskets. The sealing ring compresses when you torque the plenum down.

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