She's at it again...

[HerThing]

Well, I'll be quick as we are on a couple weekend and I want to snuggle, lmao! I'm tuned, as you all know, 91, 19psi. She starts sputtering bad under boost, but, in 3rd and 4th only. Afr reads correctly, no cel at all during or after, before, nothing. Any ideas? There is no vacuum leaks, no boost leak. The up pipe did just leaking about 10 minutes ago. Bad gasket. It's faint, but definitely leaking. Could that cause it? Boost gauge reads 19 exact, no spikes or loss. I'm so lost on this!!!! We are 2 1/2 hours from home, all my tools are there! Argh!

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[Alin]

Would you say the sputtering is pretty much surging or fluttering? My turbo does that only in 5th, but it's been years since I went WOT in 5th.

 

[HerThing]

Oh no, it's rough. It's a definite stutter step. Very rapid. Sometimes once, sometimes repeatedly till I back off or shift.

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[HerThing]

It's not misfire type stutter. More of a full boost then zero boost then full boost. Like a jerk.

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[Alin]

[MENTION=1]IGOTASTi[/MENTION] [MENTION=662]Batmobile_Engage[/MENTION] [MENTION=9]HolyCrapItsFast[/MENTION]

 

[Batmobile_Engage]

Sounds like my issue, which we've determined should be a boost leak. Yours is probably not as bad as mine, but the only way to determine this in your case is to datalog and see what's going on.

Another possibility would be a MAF that is going bad or getting dirty, though those generally throw a CEL.

Your spark plugs might need changing or possibly your fuel filter. Tough to tell without more information, or experiencing it myself.

You can probably just baby it on the way home. If you have a half tank or so, top off with some fresh fuel just to rule out that as well.

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[HerThing]

I'm at half. I think I will. I have all new exhaust gaskets on the way, new MBC, and I need to order ic gaskets

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[HerThing]

Well. Got worse. Did a roadside comp test at pepboys. Compression good. Plug was lean looking. Thinking bad injector after sitting. Gonna milk it home. Order new. Cylinder 2. P0302.

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[Batmobile_Engage]

Very possible. It finally threw a code then, eh? Just P0302? You using an Accessport?

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[HerThing]

It was a stored code. The check engine light is on only when the problem is occurring. If I hold it in boost and let it do it constantly, I get a flashing check engine light, but the cruise light doesn't come on.

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[HerThing]

No, I'm not using an accessport.

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[HerThing]

Well, her car. Cylinder 4.

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[IGOTASTi]

Oh boy!

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[HerThing]

Yup. A bit butthurt about this one.

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[IGOTASTi]

Yup. A bit butthurt about this one.

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That's sucks big time!

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[Alin]

Damn, not cool!

 

[Batmobile_Engage]

That is probably bad, but we can't say for sure, just yet. The engine may have cooled down too much to get a higher reading. The determining factor is generally the tolerance between the suspected bad cylinder and the rest.

What did the other cylinders read? If they are all reading relatively close* to each other, it might be okay.
*Within 7% tolerance from the average of other cylinders.

 

[HerThing]

1 and 3- 120psi, 2- 110psi, 4- 100psi

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[Batmobile_Engage]

Hmmm...that doesn't sound good. When you performed the test, which cylinders did you do first? As the engine cools, you will get progressively lower numbers.

I mean, you probably have a bad piston, but I'd rather you perform the test again than to just assume a bad piston and tear the motor down.

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[HerThing]

It had been sitting all weekend. Garage temps ranged from 90-120.

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